JP5037395B2 - Lower thread control device of sewing machine - Google Patents

Description

  The present invention relates to a lower thread control device for a sewing machine, and more particularly to a lower thread control device for a sewing machine that adjusts the tension of a lower thread.

  2. Description of the Related Art Conventionally, when a seam is formed on a fabric, a sewing machine using a lower thread control device that crosses a lower thread into an upper thread loop formed by an upper thread inserted through a sewing needle is used.

  This sewing machine lower thread control device includes a bobbin case that holds a bobbin around which a lower thread is wound, an inner hook that holds the bobbin case inside, and an outer hook that holds the inner hook inside. It has a mechanism. The outer hook is connected to the hook shaft that is driven in synchronization with the sewing machine main shaft, and is rotatable with respect to the inner hook. By rotating, the inner hook is passed through the upper thread loop. As a result, the lower thread control device of the sewing machine crosses the lower thread fed out of the bobbin case and supplied to the needle drop position via the needle hole of the needle plate into the upper thread loop.

  In such a lower thread control device of the sewing machine, the tension of the lower thread fed out from the bobbin case is adjusted from the viewpoint of smoothly supplying the lower thread and preventing the formation of rough seams. It has become.

  As a means for adjusting the tension of the lower thread, in a lower thread control device of a conventional sewing machine, tension is applied to the lower thread on the outer peripheral surface of the bobbin case and in the vicinity of the outlet for feeding the lower thread to the outside of the bobbin case. A lower thread tension adjusting spring to be applied is disposed. This lower thread tension adjusting spring is fixed to the peripheral wall of the bobbin case with a fixing screw. By pressing the lower thread fed from the feeding port by the urging force of the lower thread tension adjusting spring, a predetermined tension is applied to the lower thread. (For example, refer to Patent Document 1). In such a lower thread control device of the sewing machine, the pressing force on the lower thread of the lower thread tension adjusting spring is adjusted by adjusting the tightening amount of the fixing screw for fixing the lower thread tension adjusting spring to the bobbin case. Thus, the tension of the lower thread can be adjusted.

  Further, as another means for adjusting the tension of the lower thread, a permanent magnet that comes into contact with the bobbin via a disc spring that functions as a disc brake is disposed at the bottom of the bobbin case in the lower thread control device of the conventional sewing machine. ing. In addition, when the bobbin case in which the bobbin is stored outside the outer hook is stored in the inner hook, the permanent magnet is selectively attracted or removed at a position facing the permanent magnet on the side opposite to the bobbin arrangement side. Thus, an electromagnet whose polarity and magnetic force can be changed is provided so as to be able to contact and separate from the permanent magnet.

  In such a lower thread control device of the sewing machine, the polarity and magnetic force are changed so that the electromagnet rejects the permanent magnet by passing a current corresponding to the sewing speed through the coil of the electromagnet while the electromagnet is close to the permanent magnet. To do. And the lower thread control device of the sewing machine is adapted to apply a predetermined tension to the lower thread by pressing the bobbin through the disc spring by pressing the bobbin on the side where the bobbin is disposed, By adjusting the current flowing through the coil of the electromagnet, the tension on the lower thread can be adjusted (see, for example, Patent Document 2).

JP 2005-160942 A Japanese Patent Laid-Open No. 05-068764

  However, in order to adjust the tension of the lower thread in the former lower thread control device of the former sewing machine as described above, the bobbin case is taken out from the inner hook and the lower thread tension adjusting spring is fixed. The lower thread was set to an approximate tension by adjusting the tightening degree of the fixing screw, and the bobbin case was stored in the inner hook again, and trial sewing was performed to adjust the tension with the upper thread tension. As a result, in order to reset the lower thread tension, the sewing machine must be stopped, the bobbin case removed from the inner hook again, and the tightening of the fixing screw must be adjusted. There was a problem that adjustment was troublesome.

  Moreover, since the fixing screw is a small screw for fixing the lower thread tension adjusting spring to the bobbin case, it is difficult to form a scale indicating the degree of tension of the lower thread on the fixing screw.

  In particular, the inner hook in which the bobbin case is stored is stored in a floating state in the outer hook so that the upper hook loops through the inner hook. For this reason, even if an actuator for adjusting the thread tension from the outside is attached to the bobbin case, a cable for supplying electricity for operating this actuator cannot be connected. It was difficult to add an adjusting mechanism for adjusting the tension of the arm.

  Further, in the lower thread control device of the latter sewing machine, since the tension of the lower thread is adjusted using magnetic force, the pressing force against the bobbin also varies due to the variation in the distance between the electromagnet and the permanent magnet. Here, when replacing the bobbin housed inside the bobbin case, it is necessary to separate the electromagnet from the inner hook in order to remove the bobbin case from the inner hook, so the distance between the electromagnet and the permanent magnet is kept constant. It has been difficult to maintain, and as a result, it has been difficult to stably and accurately adjust the tension on the lower thread. In addition, in order to give a sufficient tension to the lower thread in the lower thread control device of the sewing machine, a large space for using a large electromagnet is necessary, so that the sewing machine becomes larger, There has been a problem that the operability when removing the bobbin case from the inner hook to replace the bobbin is significantly hindered.

  The present invention has been made in view of these points. The tension of the lower thread can be easily and accurately removed without taking out the bobbin case from the inner hook when adjusting the tension of the lower thread without increasing the size of the sewing machine. An object of the present invention is to provide a lower thread control device for a sewing machine that can adjust the thread.

  In order to achieve the above object, the bobbin thread control device of the sewing machine according to claim 1 is characterized in that a bobbin case around which a bobbin around which a bobbin thread is wound is rotatably held, and the bobbin case is disposed inside. An inner hook that holds the inner hook, and an outer hook that holds the inner hook and is rotatable with respect to the inner hook. When the bobbin is rotated, the lower thread is fed out of the bobbin case. In the lower thread control device of the sewing machine that controls the tension of the lower thread, the bobbin is disposed at a position facing the bobbin inside the inner hook so as to be movable forward and backward in the arrangement direction of the bobbin, and presses the bobbin. An actuator for imparting a force resisting the rotation of the bobbin, an external interface circuit disposed inside the inner hook and receiving a communication signal from the outside, disposed inside the inner hook, and A control circuit for controlling the force against the rotation of the bobbin by adjusting the pressing force of the actuator against the bobbin by moving the actuator forward and backward based on the communication signal received via the interface circuit; A bobbin thread tension control unit provided inside the hook and having an external power receiving circuit exposed from the inner hook and the outer hook, and arranged outside the outer hook, and the external power receiving when the outer hook is not rotating. A bobbin thread tension control unit that is movable between a contact position that contacts the circuit and the external interface circuit and a retracted position that moves away from the outer hook when the outer hook rotates. Power to the external interface circuit and contact the control circuit with respect to the movement position of the actuator. It lies in that a probe for transmitting a signal.

  According to the first aspect of the present invention, the probe is positioned in the retracted position when the outer hook is rotating, thereby preventing the probe and the outer hook from colliding with each other when the outer hook is rotating, and the outer hook not rotating. Sometimes, by moving the probe to the contact position and bringing the probe into contact with the external power receiving circuit, power can be supplied to the control circuit and a signal regarding the position of the actuator can be transmitted. The bobbin thread control device of the sewing machine according to the present invention resists the rotation of the bobbin when the bobbin thread is fed by adjusting the pressing force of the actuator against the bobbin by moving the actuator by the control circuit based on the transmitted signal. The force can be adjusted, whereby the tension on the lower thread fed out from the bobbin can be adjusted.

  The bobbin thread control device of the sewing machine according to claim 2 is characterized in that, in the bobbin thread control device according to claim 1, an elastic member is interposed between the bobbin and the bottom wall of the bobbin case, The bobbin is held between the elastic member and the actuator by a repulsive force due to the elasticity of the elastic member.

  According to the second aspect of the present invention, the elastic member is interposed between the bobbin and the bottom wall of the bobbin case, the bobbin is held between the elastic member and the actuator by the repulsive force due to the elasticity of the elastic member, By adjusting the pressing force of the actuator with respect to the bobbin, the repulsive force of the elastic member against the bobbin can be adjusted to adjust the force resisting the rotation of the bobbin when the lower thread is paid out. Thereby, the force resisting the rotation of the bobbin can be adjusted more finely, and the tension on the lower thread can be adjusted more effectively.

  The lower thread control device of the sewing machine according to a third aspect of the invention is characterized in that in the lower thread control device of the sewing machine according to the first or second aspect, the external power reception of the probe is provided inside the inner hook. A non-volatile memory is provided that maintains a memory of the position of the actuator immediately before the probe moves to the retracted position when not in contact with the circuit.

  According to the third aspect of the present invention, the position of the actuator immediately before the probe moves to the retracted position in the nonvolatile memory is stored, and the current position of the actuator stored in the nonvolatile memory is transmitted. By calculating the difference from the position of the actuator, the pressing force of the actuator can be adjusted more easily by the control circuit.

  According to a fourth aspect of the present invention, the lower thread control device of the sewing machine is the lower thread control device of any one of the first to third aspects, wherein the bobbin of the actuator faces the bobbin. A plurality of recesses are formed on the surface, and the balls are rotatably held in the respective recesses, and the actuator presses the bobbin through the balls.

  According to the fourth aspect of the present invention, the actuator presses the bobbin via the ball held in the recess formed on the surface facing the bobbin, so that the rotational force of the bobbin when the lower thread is fed out Can be absorbed by the rotation of the ball, and the rotational force of the bobbin can be prevented from being transmitted to the inner case. Thereby, it is possible to prevent the actuator from rotating due to the rotation of the bobbin and changing the position of the actuator relative to the bobbin. As a result, the lower thread control device of the sewing machine can reliably prevent the pressing force applied to the bobbin by the actuator from changing due to the rotation of the bobbin.

  As described above, according to the lower thread control device of the sewing machine according to the present invention, the bobbin case is not taken out from the inner hook when adjusting the lower thread tension without increasing the size of the sewing machine. The lower thread tension can be adjusted.

  Hereinafter, an embodiment of a bobbin thread control device for a sewing machine according to the present invention will be described with reference to FIGS.

  FIG. 1 is a side sectional view showing a lower thread control device of the sewing machine according to the present embodiment, FIG. 2 is a plan sectional view showing a case where the lower thread control device of FIG. 1 is cut along line AA, and FIG. FIG. 2 is a schematic block diagram showing a sewing machine including the lower thread control device in FIG. 1.

  As shown in FIGS. 1 and 2, the lower thread control device 1 of the sewing machine according to the present embodiment includes a support plate opposed to each other with a predetermined gap and a support shaft 2c that connects both support plates, and the support shaft 2c. A bobbin 2 around which a lower thread (not shown) is wound, a bobbin case 3 that holds the bobbin 2 inside, an inner hook 5 that holds the bobbin case 3 inside, and an outer hook 6 that holds the inner hook 5 inside. ing.

  The outer hook 6 is formed in a substantially cylindrical shape with one surface opened. A hook shaft 8 that rotates in synchronization with the sewing machine main shaft 7 is connected to the outer surface of the bottom wall of the outer hook 6. At the opening edge of the outer hook 6 is formed a sword tip 6a for catching an upper thread loop formed by an upper thread inserted through a needle hole of a sewing needle (not shown). The outer hook 6 rotates in synchronism with the driving of a needle bar (not shown) which is attached to the sewing machine main shaft 7 and moves up and down by a sewing needle attached to the lower side by the rotation of the hook shaft 8. ing.

  The inner hook 5 is formed in a substantially cylindrical shape with one surface opened, and is disposed in the outer hook 6 so that the bottom wall of the inner hook 5 faces the bottom wall of the outer hook 6. It is held so as not to rotate in a floating state.

  The bobbin case 3 has a substantially cylindrical shape with an opening on one surface, and a bobbin thread wound around the support shaft 2c of the bobbin 2 held inside is disposed on a part of the outer peripheral wall of the bobbin case 3. A feed-out port (not shown) that feeds outside is formed. The bobbin case 3 is housed inside the inner hook 5 such that one of the support plates of the bobbin 2 held inside the first support plate 2 a faces the bottom wall of the inner hook 5. A leaf spring 9 is interposed as an elastic member between the second support plate 2 b and the bottom wall of the bobbin case 3, and the second support plate 2 b in the bobbin 2 receives a repulsive force due to the elasticity of the leaf spring 9. It is like that.

  The lower thread control device 1 is configured such that the lower thread is fed out of the bobbin case 3 while the bobbin 2 rotates, and the inner hook 5 is placed on the upper thread loop captured by the sword tip 6a by the rotation of the outer hook 6. The lower thread is made to intersect with the upper thread loop.

  In such a bobbin thread control device 1, a bobbin thread tension control unit 11 for adjusting the tension with respect to the bobbin thread is arranged inside the inner hook 5, and the bobbin thread tension control unit 11 serves as an actuator. The case type actuator 13 is provided.

  The case-type actuator 13 includes an inner case 15 having one surface opened and configured in a substantially cylindrical shape, and an outer case 16 having one surface opened and substantially cylindrical and having a diameter larger than that of the inner case 15. A male screw 15 a is formed on the outer peripheral surface of the inner case 15, and a female screw 16 a is formed on the inner peripheral surface of the outer case 16. The outer case 16 is arranged so that its bottom wall faces the bottom wall of the inner hook 5 and is fixed inside the inner hook 5. The inner case 15 faces the bottom of the inner case 15 while facing each other's opening. The wall is disposed so as to face the first support plate 2a of the bobbin 2, and is coupled to the outer case 16 by screwing both screws 15a, 16a.

  In both cases, a stepping motor 18 having a stator coil 18a and a rotor magnet 18b arranged concentrically with each other is provided. The stator coil 18a is fixed inside the outer case 16, and the rotor magnet 18 b is fixed inside the inner case 15. In the stepping motor 18, when an excitation current is input to the stator coil 18a, the rotor magnet 18b obtains a rotational force.

  The case type actuator 13 expands and contracts in the axial direction as the inner case 15 rotates as the rotor magnet 18b rotates. As a result, the inner case 15 of the case type actuator 13 can be The bottom wall of the inner case 15 presses the first support plate 2a. Furthermore, since both the cases 15 and 16 are coupled by screwing both screws 15a and 16a, the inner case 15 does not move except when the inner case 15 moves forward and backward by driving the stepping motor 18. Thereby, when the bobbin 2 is rotated, the position of the inner case 15 with respect to the first support plate 2a is maintained.

  The bobbin 2 is held between the case-type actuator 13 and the leaf spring 9 by a repulsive force due to the elasticity of the leaf spring 9. Here, in the lower thread control device 1 according to the present embodiment, the force with which the lower thread is fed out from the bobbin 2 can be adjusted by the force resisting the rotation of the bobbin 2 when the lower thread is fed out. 13, as the pressing force of the inner case 15 against the bobbin 2 increases, the frictional force between the inner case 15 and the bobbin 2 increases. Accordingly, the bobbin 2 rotates when the lower thread is fed. The resistance to resistance will increase.

  Further, as the repulsive force of the leaf spring 9 against the second support plate 2b is increased, the frictional force between the leaf spring 9 and the second support plate 2b increases, and accordingly, the bobbin 2 rotates when the lower thread is fed. The resistance will increase. Since the repulsive force of the leaf spring 9 against the second support plate 2b is proportional to the amount of displacement of the leaf spring 9, the inner case 15 of the case type actuator 13 moves forward and backward to adjust the pressing force against the bobbin 2 by the inner case 15. Thus, the repulsive force of the leaf spring 9 can be adjusted.

  The lower thread control device 1 adjusts the pressing force of the inner case 15 against the bobbin 2, and further adjusts the repulsive force of the leaf spring 9 to thereby rotate the bobbin 2 when the lower thread is fed. It is possible to adjust the tension with respect to the lower thread by adjusting the force with which the lower thread is fed out from the bobbin 2 by increasing or decreasing the resistance force.

  For example, in the lower thread control device 1, as shown in FIG. 1, when the inner case 15 is moved in the axial direction of the case type actuator 13, the pressing force of the inner case 15 against the first support plate 2a is Since the repulsive force of the leaf spring 9 against the second support plate 2b is small, the frictional force between the leaf spring 9 and the second support plate 2b is small. Thereby, the force resisting the rotation of the bobbin 2 at the time of lower thread feeding is also reduced, and the tension on the lower thread is weakened.

  Further, in the lower thread control device 1, as shown in FIG. 4, when the inner case 15 is moved in the axial direction of the case type actuator 13 in the direction extending from FIG. 1, the first support plate 2a of the inner case 15 is used. 1 is larger than the state of the position of the inner case 15 in FIG. 1, and the repulsive force of the leaf spring 9 against the second support plate 2b is also increased. Therefore, the frictional force between the leaf spring 9 and the second support plate 2b is also increased. growing. Thereby, since the force resisting the rotation of the bobbin 2 at the time of lower thread feeding is increased, the tension on the lower thread can be adjusted more strongly than the state shown in FIG.

  Further, in the lower thread control device 1, as shown in FIG. 5, when the inner case 15 is moved to such an extent that the leaf spring 9 is almost crushed, the pressing force of the inner case 15 against the first support plate 2a is the maximum. Thus, the repulsive force of the leaf spring 9 against the second support plate 2b is also increased, so that the frictional force between the leaf spring 9 and the second support plate 2b is also increased. As a result, the force resisting the rotation of the bobbin 2 when the lower thread is fed out can be increased, so that the tension on the lower thread can be further increased than the state shown in FIGS.

  The outer surface of the bottom wall of the inner case 15 is formed with a plurality of recesses 15b for rotatably holding the balls 20, and the inner case 15 is connected to the first support plate via the balls 20 held in the respective recesses 15b. 2a is pressed. The positions where the recesses 15b are arranged are preferably on the same circumference as large as possible on the bottom wall of the inner case 15, and are formed at uniform intervals in the circumferential direction of the inner case 15. For example, when three recesses 15b are formed, it is preferable that they are arranged on the same circumference with an interval of 120 °. As a result, the case type actuator 13 can transmit the pressing force to the first support plate 2a, and the load on the bottom wall of the inner case 15 due to the rotation of the bobbin 2 when the lower thread is fed out by the rotation of the ball 20 By absorbing, the load received by the inner case 15 due to the rotation of the bobbin 2 is reduced.

  The tension control unit includes a circuit board 22 disposed between the bottom wall of the outer case 16 of the case-type actuator 13 and the bottom wall of the inner hook 5 inside the inner hook 5. A control circuit 23 composed of, for example, a CPU for controlling and driving the case type actuator 13 is formed on the bottom surface of the material 22a facing the bottom wall of the inner hook 5. The control circuit 23 is provided with storage means such as ROM, RAM, IF, etc. necessary for mechanically and electrically controlling the case type actuator 13, as well as, for example, a flash ROM that maintains data storage even when no power is supplied. A non-volatile memory 28 is provided.

  Further, on the bottom surface of the base material 22 a in the circuit board 22, a control circuit power supply circuit 30 that supplies power to the control circuit 23, an actuator driver circuit 31, and an actuator drive power supply circuit 32 that supplies power to the driver circuit 31. Is formed. Further, on the bottom surface of the base material 22a, an external power receiving circuit 33 and an external power receiving circuit 33 that receive power from the outside when the outer hook 6 is not rotating and supply the power to the power circuit 30 for the control circuit and the power circuit 32 for driving the actuator. Is formed, and a contact detection circuit 35 for detecting that power is received and an external interface circuit 36 for mediating transmission / reception of communication signals between the outside and the control circuit 23 are formed. Further, openings 5a and 6b are formed at positions on the bottom walls of the outer hook 6 and the inner hook 5 and facing these external power receiving circuit 33, contact detection circuit 35 and external interface circuit 36. The external power receiving circuit 33, the contact detection circuit 35, and the external interface circuit 36 are exposed from the outer hook 6 and the inner hook 5.

  Then, the control circuit 23 receives a communication signal regarding the position of the bobbin 2 relative to the first support plate 2a by the case type actuator 13 from the outside, and the case type actuator 13 of the case type actuator 13 is connected via the driver circuit 31 based on the received communication signal. By driving the stepping motor 18, the position of the inner case 15 is adjusted to adjust the pressing force.

  Electric power is supplied to the driver circuit 31 via the actuator drive power supply circuit 32 by contacting the inner hook 5 and the external power receiving circuit 33 exposed from the bottom face of the outer hook 6 on the bottom surface side of the outer hook 6. In addition, a probe 38 for supplying power to the control circuit 23 through the control circuit power supply circuit 30 is provided.

  The probe 38 includes a flexible wiring board 42 having a long plate shape as a whole, which includes a long power supply wiring 39, a contact detection wiring 40, and a communication signal wiring 41, and is formed on one surface of a base material 42 a in the flexible wiring board 42. A plastic plate 43 having a thickness of, for example, about 0.5 mm, which is formed in a wedge shape having a slightly longer width than the width of the base material 42a and a gentle side shape, is preferably attached. The probe 38 is formed in a wedge shape with a gentle side shape.

  Each wiring is in a state of being insulated from each other. At the tip of each wiring 39, 40, 41, the power feeding wiring 39 contacts the external power receiving circuit 33, and the contact detection wiring 40 contacts the contact detection circuit 35. It is exposed from the base material 42a of the flexible wiring board 42 so that the communication signal wiring 41 contacts the external interface circuit 36.

  The probe 38 is sandwiched between a pair of rollers 45a and 45b. One of the rollers 45a and 45b is a driving roller 45a and the other is a driven roller 45b. The probe 38 is supported by the rollers 45a and 45b by the rotational driving of the driving roller 45a, and is in a contact position when the outer hook 6 stops rotating and a retracted position away from the outer hook 6 when the outer hook 6 is not rotating. It is possible to move between.

  Further, a guide (not shown) for guiding the wirings 39, 40, 41 of the probe 38 to the circuits 33, 35, 36 is provided on the back surface of the circuit board 22, and the probe 38 is just fitted into the guide. It is formed in a wedge shape with an angle. The probe 38 is moved from the retracted position to the contact position and immediately before contact with each circuit 33, 35, 36, so that the probe 38 is fitted to the wedge-shaped guide by the wedge shape of the probe 38. It is arranged to be guided. Thereby, even if the movement position of the probe 38 is slightly shifted in the vertical direction, the wirings 39, 40, 41 are in contact with the corresponding circuits 33, 35, 36.

  In this embodiment, the probe 38 is formed by adhering the plastic plate 43 to the flexible wiring board 42. However, the present invention is not limited to this, and for example, each wiring 39, 40, 41 is provided. It is good also as a structure coat | covered with a hard rod-shaped coating | covering material.

  As shown in FIG. 6, the contact detection wiring 40 of the probe 38 is connected to a host computer 47 that controls driving of each part of the sewing machine 46 such as driving of the sewing machine spindle 7 through a detection circuit 51 provided in the sewing machine 46. The host computer 47 detects that the contact detection wiring 40 has contacted the contact detection circuit 35 of the lower thread tension control unit 11 through the ground line 48 by the detection circuit 51.

  The power supply wiring 39 is connected to an external power supply circuit 52 provided in the sewing machine 46. When the external power supply circuit 52 detects that the contact detection wiring 40 contacts the contact detection circuit 35 by the detection circuit 51, Supply of power to the lower thread tension control unit 11 is started via the power supply wiring 39 and the external power receiving circuit 33.

  The communication signal wiring 41 is connected to a host computer 47 via a communication circuit 50 provided in the sewing machine 46, and the host computer 47 relates to the position of the inner case 15 relative to the first support plate 2 a via the communication circuit 50. An instruction signal is transmitted to the control circuit 23 of the tension control unit. The nonvolatile memory 28 of the control circuit 23 realizes the pressing force immediately before the power supply wiring 39 is separated from the external power reception circuit 33 when the power supply wiring 39 of the probe 38 and the external power reception circuit 33 are not in contact with each other. The memory of the position of the inner case 15 is maintained.

  In the vicinity of the contact position between the probe 38 and each of the circuits 33, 35, 36 outside the outer hook 6, the presence / absence of the probe 38 at the contact position is checked in order to confirm whether the probe 38 has moved to the retracted position. A sensor (not shown) for detection is provided, and the host computer 47 starts driving the sewing machine spindle 7 after confirming that the probe 38 has moved to the retracted position by the sensor.

  The sewing machine 46 is provided with, for example, an optical sensor 53 having a light emitting element and a light receiving element in the vicinity of the outer hook 6 as a detecting means for detecting the remaining amount of the lower thread wound around the bobbin 2. The optical sensor 53 detects the remaining amount of lower thread by the amount of light received by the light receiving element from the light emitting element via the bobbin 2, and inputs the detected remaining amount of lower thread to the host computer 47. .

  Further, the sewing machine 46 is input with instruction signals for various parts of the sewing machine 46 to perform various operations such as rotation start, rotation stop, rotation speed control, and detection of the remaining amount of bobbin thread in the bobbin 2. An operation pedal 55 is provided as an operation means, and the operation pedal 55 transmits each instruction signal to the host computer 47 based on an operation by an operator of the sewing machine 46.

  Further, the sewing machine 46 is provided with a touch panel 56 on which a liquid crystal display panel is stacked as an input means. The touch panel 56 receives each instruction signal such as a sewing condition selected by the operator according to the display on the liquid crystal display panel. The data is transmitted to the host computer 47. In addition, the touch panel 56 allows the operator to designate and input an arbitrary tension for the lower thread.

  Next, the effect | action of this embodiment is demonstrated using FIG.

  The probe 38 needs to be positioned at a retracted position away from the outer hook 6 in order to prevent the outer hook 6 and the probe 38 from being damaged due to contact between the probe 38 and the outer hook 6 when the outer hook 6 rotates. Even when the sewing machine 46 is turned on, the probe 38 is in the retracted position.

  In this state, as shown in FIG. 5, when the operator first presses the operation pedal 55 to start the sewing operation by the sewing machine 46 (ST1), the host computer 47 indicates that the operation pedal 55 has been pressed. And the remaining amount of the lower thread is detected by the optical sensor 53 (ST2).

  Further, while the optical sensor 53 detects the remaining amount of the lower thread, the host computer 47 applies a pressing force against the first support plate 2a of the bobbin 2 by the inner case 15 for applying a predetermined tension to the lower thread. The position of the inner case 15 that can be realized is calculated (ST3). The predetermined tension is, for example, the tension designated by the operator using the touch panel 56 according to the sewing conditions such as the type of cloth or thread to be sewn, or the optimum tension calculated by the host computer 47, Is a tension that matches a specified sewing condition among a plurality of tensions stored in the memory 49 of the host computer 47 in accordance with various sewing conditions.

  Here, the optimum tension for the lower thread varies depending on the sewing conditions such as the cloth and thread type of the sewing product. Further, the lower thread fed from the bobbin 2 changes the distance from the center of rotation of the bobbin 2 to the bobbin case 3 depending on the remaining amount of the lower thread in the bobbin 2, and the tension to the lower thread also depends on the lower thread remaining amount. It depends on. Therefore, when the host computer 47 calculates the optimum tension for the lower thread, various conditions such as the sewing conditions input by the operator using the touch panel 56 and the detected lower thread remaining amount are taken into consideration. Then, the optimum tension for the lower thread is calculated. The tension of the lower thread can be expressed by the following formula.

Lower thread tension (f _T ) = force against the rotation of the bobbin 2 when the lower thread is fed = the radius (R) of the lower thread wound around the bobbin 2 × the frictional force between the leaf spring 9 and the bobbin 2 (f _r ) = lower thread remaining amount (T _r ) × conversion coefficient (K _r ) of the radius × friction coefficient (μ) between leaf spring 9 and bobbin 2 × leaf spring 9 constant (K _s ) × position of inner case 15 (X)
f _T = Rf _r = T _r · K _r · μ · K _s · x

For this reason, the position of the inner case 15 is calculated by the lower thread tension / (lower thread remaining amount × the conversion coefficient of the radius × the friction coefficient × the plate spring 9 constant).
x = f _T / T _r · K _r · μ · K _s

  Subsequently, the host computer 47 stores the remaining amount of the lower thread detected by the optical sensor 53 in the memory of the host computer 47, and rotates the driving roller 45a to move the probe 38 from the retracted position to the contact position ( In step ST4), each wiring of the probe 38 is brought into contact with each corresponding circuit on the circuit board 22 of the tension control unit.

  Here, the host computer 47 determines whether or not the contact detection wiring 40 and the contact detection circuit 35 are connected (ST5), and determines that the contact detection wiring 40 and the contact detection circuit 35 are not connected. In this case (No in ST5), it is determined whether or not the contact detection wiring 40 and the contact detection circuit 35 are connected repeatedly (ST5). If the host computer 47 determines that the contact detection wiring 40 and the contact detection circuit 35 are connected (Yes in ST5), the external power supply circuit 52 and the communication circuit 50 are turned on (ST6). .

  As a result, the host computer 47 supplies power to the actuator driver circuit 31 via the power supply wiring 39 and the external power receiving circuit 33 through the actuator drive power supply circuit 32, and to the control circuit 23 through the control circuit power supply circuit 30. The power is supplied, and the control circuit 23 of the tension control unit is activated and enters a standby state for a communication signal from the host computer 47. Further, the host computer 47 transmits a communication signal related to the position of the inner case 15 calculated via the communication wiring and the external interface circuit 36 to the control circuit 23, whereby the control circuit 23 receives the position related to the position from the host computer 47. A communication signal is received (ST7).

  Subsequently, the control circuit 23 calculates a difference between the current position of the inner case 15 stored in the nonvolatile memory 28 and the position of the inner case 15 received from the host computer 47, and passes the actuator driver circuit 31. The inner case 15 is moved by driving the stepping motor 18 (ST8).

  Further, the host computer 47 rotationally drives the drive roller 45a to move the probe 38 from the contact position to the retracted position (ST9), and then the probe 38 is moved to the retracted position by a probe detection sensor (not shown) and positioned at the contact position. It is determined whether or not to perform (ST10). When the host computer 47 determines that the probe 38 is still located at the contact position by the sensor (No in ST10), the host computer 47 repeatedly determines whether the probe 38 is not located at the contact position (ST10). Is determined not to be in the contact position (Yes in ST10), sewing is started in accordance with the designated sewing conditions (ST11).

  According to this embodiment, when the outer hook 6 rotates, the probe 38 is positioned at the retracted position, thereby preventing the probe 38 and the outer hook 6 from colliding with each other while the outer hook 6 is rotating. When the probe 38 is rotated, the probe 38 is moved to the contact position, and the wiring of the probe 38 is brought into contact with the corresponding circuit of the circuit board 22, thereby supplying electric power to the control circuit 23 and outputting a signal related to the position of the case type actuator 13. Can be sent. The lower thread control device 1 according to the present embodiment moves the inner case 15 by the control circuit 23 and adjusts the pressing force of the case type actuator 13 on the bobbin 2 to rotate the bobbin 2 when the lower thread is fed. The resisting force can be adjusted, whereby the tension on the lower thread fed out from the bobbin 2 can be adjusted.

  Accordingly, the tension of the lower thread can be adjusted easily and accurately without taking out the bobbin case 3 from the inner hook 5 when adjusting the tension of the lower thread without increasing the size of the sewing machine 46.

  Further, a leaf spring 9 is interposed between the bobbin 2 and the bottom wall of the bobbin case 3, and the bobbin 2 is held between the leaf spring 9 and the case type actuator 13 by a repulsive force due to the elasticity of the leaf spring 9. By adjusting the pressing force of the case type actuator 13 against 2, the repulsive force of the leaf spring 9 against the bobbin 2 can be adjusted, and the force resisting the rotation of the bobbin 2 when the lower thread is paid out can be adjusted. Thereby, the force resisting the rotation of the bobbin 2 can be adjusted more finely, and the tension on the lower thread can be adjusted more effectively.

  Further, in the non-volatile memory 28 of the control circuit 23, the position of the inner case 15 with respect to the first support plate 2a immediately before the probe 38 moves to the retracted position when the probe 38 is not in contact with the external power receiving circuit 33 is stored. By calculating the difference between the current position of the inner case 15 stored in the nonvolatile memory 28 and the position of the inner case 15 received from the host computer 47, the control circuit 23 can more easily press the actuator. Can be adjusted.

  Furthermore, the inner case 15 of the actuator presses the first support plate 2a via the ball 20 held in the recess 15b formed on the surface of the inner case 15 facing the first support plate 2a of the bobbin 2. It is like that. As a result, the lower thread control device 1 can press the first support plate 2a and absorbs the rotational force of the bobbin 2 when the lower thread is fed out by the rotation of the ball 20, so that the rotational force of the bobbin 2 is increased. Since transmission to the case 15 can be prevented, it is possible to prevent the inner case 15 from being rotated by the rotation of the bobbin 2 and the position of the inner case 15 relative to the bobbin 2 from being changed. As a result, the lower thread control device 1 can reliably prevent the pressing force of the inner case 15 against the bobbin 2 from being changed by the rotation of the bobbin 2.

  In addition, this invention is not limited to the said embodiment, A various change is possible as needed.

  For example, in the lower thread control device 1 in the present embodiment, the bobbin 2 is held between the leaf spring 9 and the case type actuator 13 by the repulsive force due to the elasticity of the leaf spring 9 as an elastic member, and the leaf spring 9 By adjusting the repulsive force, the force resisting the rotation of the bobbin 2 at the time of lower thread feeding is adjusted, but the present invention is not limited to this. In the present invention, the case type actuator 13 moves forward and backward in the arrangement direction of the bobbin 2, thereby adjusting the pressing force against the bobbin 2, thereby adjusting the force resisting the rotation of the bobbin 2 when the bobbin thread is fed. If it exists, the elastic member may not be interposed between the bobbin 2 and the bobbin case 3.

  Further, in this embodiment, the case type actuator 13 including the inner case 15 and the outer case 16 is used as an actuator for pressing the bobbin 2, but the present invention is not limited to this, and the bobbin 2 Any actuator that can adjust the pressing force on the bobbin by moving back and forth may be used.

Side surface sectional drawing which shows one Embodiment of the bobbin thread control apparatus of the sewing machine which concerns on this invention Front sectional view taken along line AA in the lower thread control device of FIG. The block diagram which shows the structure of the lower thread control apparatus of FIG. Side surface sectional view showing a case where the actuator in the lower thread control device of FIG. 1 is moved to the bobbin side Side surface sectional view showing a case where the actuator in the lower thread control device of FIG. 4 is moved on the bobbin side Electrical circuit diagram of the lower thread control device of FIG. The flowchart which shows the adjustment process of the bobbin thread tension in the bobbin thread control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bobbin thread control apparatus 2 Bobbin 2a 1st support plate 2b 2nd support plate 3 Bobbin case 5 Inner hook 6 Outer hook 9 Leaf spring 10 Lower thread 13 Case type actuator 15 Inner case 15b Recessed part 16 Outer case 18 Stepping motor 20 Ball 22 Circuit board 23 Control circuit 28 Non-volatile memory 30 Control circuit power supply circuit 31 Driver circuit 32 Actuator drive power supply circuit 33 External power receiving circuit 35 Contact detection circuit 36 External interface circuit 38 Probe 39 Power supply wiring 40 Contact detection wiring 41 Communication signal wiring

Claims (4)

A bobbin case that rotatably holds a bobbin around which a bobbin thread is wound, an inner hook that holds the bobbin case inside, an outer hook that holds the inner hook and is rotatably provided to the inner hook. In a lower thread control device of a sewing machine that has a hook and controls the tension of the lower thread when the lower thread is fed out of the bobbin case while the bobbin rotates,
An actuator that is provided at a position facing the bobbin in the inner hook so as to be movable forward and backward in the arrangement direction of the bobbin, and applies a force against the rotation of the bobbin by pressing the bobbin;
An external interface circuit disposed inside the inner hook and receiving a communication signal from the outside;
The bobbin is rotated by adjusting the pressing force applied to the bobbin by the actuator by moving the actuator forward and backward based on the communication signal that is disposed inside the inner hook and received via the external interface circuit. Control circuit to control the resisting force,
A bobbin thread tension control unit that is disposed inside the inner hook and includes an external power receiving circuit that is exposed from the inner hook and the outer hook;
It is arranged outside the outer hook and moves between a contact position that contacts the external power receiving circuit and the external interface circuit when the outer hook is not rotating and a retracted position that is separated from the outer hook when the outer hook is rotating. A probe capable of contacting the external power receiving circuit to supply power to the lower thread tension control unit and contacting the external interface circuit to transmit a communication signal related to the movement position of the actuator to the control circuit. A bobbin thread control device for a sewing machine comprising:   The elastic member is interposed between the bobbin and the bottom wall of the bobbin case, and the bobbin is held between the elastic member and the actuator by a repulsive force due to elasticity of the elastic member. The lower thread control device of the sewing machine according to claim 1.   A non-volatile memory is provided in the inner hook for maintaining the memory of the position of the actuator immediately before the probe moves to the retracted position when the probe is not in contact with the external power receiving circuit. The lower thread control device of the sewing machine according to claim 1 or 2.   A plurality of recesses are formed on a surface of the actuator facing the bobbin, and a ball is rotatably held in each recess, and the actuator presses the bobbin via the ball. The lower thread control device for a sewing machine according to any one of claims 1 to 3.

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