Sewing machine with

Abstract

To provide a sewing machine that contributes to a reduction in the possibility that the sewing machine behaves in a manner not intended by a user at the start or restart of sewing when sewing is performed using a movement detection device.SOLUTION: The sewing machine includes a needle bar, a needle plate, a presser bar, a sewing machine motor, a presser motor, and a processor. The sewing machine motor moves the needle bar in the up-down direction within a range including a needle-up position where the lower end of the sewing needle is located above the needle plate and a needle-down position where the lower end of the sewing needle is located below the needle plate. The presser motor moves the presser bar in the up-down direction between a normal position and a lowered position. The processor executes a first stitch process (from S5 to S9) for moving the presser bar from the lowered position to the normal position after moving the needle bar from the needle lowered position to the needle raised position at least either at the start of stitching or at the restart of stitching. Based on the detection result of the movement detection device, the processor executes the second stitch processing of moving the needle bar in the up-down direction in a state where the presser bar is at the normal position (S12).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a sewing machine. [Background technology]

[0002] A conventional sewing machine can adjust the length of a stitch based on the detection results of a movement detection device that detects movement of the fabric (see Patent Document 1). The movement detection device includes a light detection unit that detects movement of the fabric by detecting light, a main body that has the light detection unit built in and is detachable from the presser bar of the sewing machine, and a presser foot support unit that is detachable from the main body and has a cloth presser unit that can come into contact with the fabric. A window that allows light to pass through is provided on the bottom of the main body, and when the presser foot support unit is attached to the main body, the cloth presser unit is located below the bottom of the main body. The movement detection device outputs a detection result corresponding to the amount of movement of the fabric to the sewing machine.

[0003] When a conventional sewing machine is set to free motion mode, it moves the feed dog to a position where it does not protrude above the needle plate and positions the presser foot a predetermined distance above the sewing material to perform sewing (see Patent Document 2). Specifically, the sewing machine switches the feed dog to the inactive position, controls the presser foot lifting mechanism to lower the presser foot to a pressing position where it contacts the sewing material, and detects the thickness of the sewing material from the detection signal of the height position detector at the pressing position. Based on the detected thickness, the sewing machine stops the presser foot at a floating position where it is raised a predetermined distance above the top surface of the sewing material, and controls the sewing machine motor to move the needle bar to a set position just before the tip of the needle pierces the workpiece. A user performs sewing by manually moving the sewing material in accordance with the movement of the needle bar. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2023-035293 [Patent Document 2] JP 2009-291416 A Summary of the Invention [Problem to be solved by the invention]

[0005] When sewing in free motion mode using a conventional sewing machine and driving the needle bar based on the detection results of the movement detection device, the needle may pull the sewing material upward as the needle bar rises at the start of sewing, causing the sewing material to lift up from the needle plate. If the movement of the sewing material at this time is detected by the movement detection device, the sewing machine may behave in an unintended manner, such as starting sewing based on the detection results of the movement detection device.

[0006] An object of the present invention is to provide a sewing machine that contributes to reducing the possibility of the sewing machine behaving in an unintended manner when starting or resuming sewing when sewing using a movement detection device. [Means for solving the problem]

[0007] A sewing machine according to one aspect of the present invention includes a needle bar extending in a vertical direction, a needle plate having a needle hole formed therein through which a sewing needle attached to the needle bar can be inserted, a presser bar extending in the vertical direction and having a movement detection device attached thereto that detects movement of a workpiece placed on the needle plate, a sewing machine motor that moves the needle bar in the vertical direction in a range including a needle up position where a lower end of the sewing needle is above the needle plate and a needle down position where the lower end of the sewing needle is below the needle plate, and a sewing machine motor that moves the presser bar in the vertical direction in a range including a normal position and a lowered position where the lower end of the presser bar is below the normal position. The sewing machine includes a presser motor that moves the needle bar in the up and down direction, and a processor, and the processor is configured to drive the sewing machine motor to move the needle bar from the needle down position to the needle up position at least either when sewing starts or when sewing resumes, and then drive the presser motor to execute a first stitch process that moves the presser bar from the lowered position to the normal position, and a second stitch process that drives the sewing machine motor based on the detection result of the movement detection device to move the needle bar in the up and down direction with the presser bar in the normal position. The first stitch process executed by the sewing machine processor contributes to the movement detection device attached to the presser bar in the lowered position limiting the upward movement of the sewn material as the needle pulls the sewn material upward as the needle bar moves from the lowered position to the normal position, compared to when the presser bar is in the normal position when sewing the first stitch at the start of sewing or when sewing resumes. The first stitch processing of the sewing machine contributes to preventing the second stitch from being erroneously sewn based on the detection result of the movement detection device when the first stitch processing is being executed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of the sewing machine 1 to which the movement detection device 9 is attached. [Figure 2] (A) is a left side view of the sewing machine 1 equipped with the movement detection device 9, (B) is an enlarged view of the movement detection device 9 with the presser foot 25 in contact with the workpiece C, and (C) is an enlarged view of the movement detection device 9 with the presser foot 25 positioned a predetermined distance above the workpiece C. [Figure 3] FIG. 2 is a perspective view of a movement detection device 9. [Figure 4] 2 is a block diagram showing the electrical configuration of the sewing machine 1. FIG. [Figure 5] 10 is a flowchart of a main process that is executed when the movement detection device 9 is attached. [Figure 6] 10 is a graph showing the results of an evaluation test of a comparative example. [Figure 7] 1 is a graph showing the results of evaluation tests of examples. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will be described with reference to the drawings. In FIG. 1 , the up-down direction, the lower-left direction, the upper-right direction, the upper-left direction, and the lower-right direction correspond to the up-down direction, the left direction, the right direction, the rear direction, and the front direction of the sewing machine 1, respectively. The longitudinal direction D2 of the bed 11 and the arm 13 corresponds to the left-right direction of the sewing machine 1. The lateral direction D1 of the bed 11 and the arm 13 in a plane parallel to the horizontal direction corresponds to the front-rear direction of the sewing machine 1. In the sewing machine 1, the side on which the leg post 12 is located is the right side. The extension direction of the leg post 12 corresponds to the up-down direction of the sewing machine 1. The direction perpendicular to the up-down direction, from the needle bar 15 toward the presser bar 16, is the rearward direction and is defined as the forward direction F. The opposite direction of the forward direction F is the forward direction and is defined as the reverse direction B. The forward direction F and the reverse direction B are directions along the lateral direction D1.

[0010] As shown in Figure 1, the sewing machine 1 includes a bed 11, a leg post 12, and an arm 13. The leg post 12 extends vertically. The bed 11 has a bed surface 10 and extends leftward from the lower end of the leg post 12. The arm 13 extends leftward above the bed 11 from the upper end of the leg post 12 in parallel with the bed 11. The arm 13 has a head 14 at its left end.

[0011] The bed surface 10 extends horizontally. The bed surface 10 is provided with a needle plate 41 that also extends horizontally. The needle plate 41 is formed with a needle eye 40 through which a sewing needle 17 attached to a needle bar 15 can be inserted. The bed 11 is provided with a feed mechanism 31 shown in FIG. 4 and a shuttle mechanism (not shown) below the needle plate 41. The feed mechanism 31 is provided with a feed dog 32. The feed mechanism 31 drives the feed dog 32 to move the workpiece in a forward direction F or a reverse direction B by a predetermined amount. The forward direction F corresponds to the direction in which the sewing machine 1 is positioned relative to the user. The shuttle mechanism is provided with a shuttle. The shuttle mechanism drives the shuttle to entangle the upper thread with the lower thread.

[0012] As shown in FIG. 1, a vertically long liquid crystal display (LCD) 43 and a touch screen 44 are provided on the front side of the leg column 12. The LCD 43 displays messages and the like necessary for sewing work. The touch screen 44 is provided in front of the LCD 43. When the user selects an item displayed on the LCD 43 with a pointing device such as a finger or a dedicated stylus pen, the selected position is detected by the touch screen 44. The user can input various instructions to the sewing machine 1 via the touch screen 44.

[0013] A plurality of switches, including a start / stop switch 45, are provided on the front surface of the arm 13. The start / stop switch 45 is a switch for instructing the start and stop of a sewing operation. An openable sewing machine cover (not shown) is provided on the top of the arm 13. The sewing machine cover of the arm 13 is not shown in Figures 1 and 2(A). A thread storage compartment 50 is provided on an upper surface 53 of the arm 13 that is exposed when the sewing machine cover is open. The thread storage compartment 50 is a recessed portion that is recessed downward and can store a thread spool T around which an upper thread is wound. A spool pin 51 extends leftward from the inner wall surface on the right side of the thread storage compartment 50. The thread spool T is attached to the sewing machine 1 by inserting the spool pin 51 into the thread spool T insertion hole.

[0014] The head 14 is provided with a needle bar mechanism and a presser foot mechanism (not shown) inside the head 14. As shown in Figures 2(A) to 2(C), the needle bar mechanism has a needle bar 15 that extends vertically and moves the needle bar 15 back and forth in the vertical direction. The lower end of the needle bar 15 protrudes downward from the lower end of the head 14. A sewing needle 17 is removably attached to the lower end of the needle bar 15. The sewing needle 17 attached to the needle bar 15 moves back and forth in the vertical direction. The upper thread inserted into the sewing needle 17 is entangled with the bobbin thread by the shuttle to form a stitch on the material being sewn. The presser foot mechanism has a presser bar 16 that extends vertically and moves the presser bar 16 back and forth in the vertical direction. The lower end of the presser bar 16 protrudes downward from the lower end of the head 14.

[0015] The movement detection device 9 is used when the user manually moves the sewing object C placed on the bed surface 10 while sewing without using the feed dog 32. The movement detection device 9 detects the movement of the sewing object C placed on the needle plate 41 and outputs a detection result corresponding to the amount of movement of the sewing object C. The movement detection device 9 detects the amount of movement of the sewing object C placed on the bed 11 below the presser bar 16 and outputs the result to the sewing machine 1. The sewing machine 1 adjusts the length of the stitches formed on the sewing object C by controlling the drive of the sewing machine motor 33 shown in FIG. 4 based on the amount of movement per unit time of the sewing object C, i.e., the movement speed. The movement detection device 9 is detachable from the presser foot 25. The presser foot 25 is positioned a predetermined distance above the top surface of the sewing object C in its normal position (described below). By limiting the vertical movement of the sewing object C within a predetermined distance, the sewing object C placed on the bed surface 10 is prevented from lifting up.

[0016] 3, the movement detection device 9 includes a housing 95, a sensor 97, a cable 99, and an attachment 98. The housing 95 is a rectangular parallelepiped that is longer in the front-to-back direction than in the left-to-right direction. The housing 95 is detachable from the presser bar 16 of the sewing machine 1. The housing 95 houses the sensor 97.

[0017] The sensor 97 is located above an opening 100 formed in the bottom surface 96 of the housing 95. The sensor 97 has a light-emitting element 971 and a light-receiving element 972 shown in FIG. 4. The light-emitting element 971 and the light-receiving element 972 are located above the opening 100. The light-emitting element 971 emits light toward the sewing object C to detect the amount of movement of the sewing object C. The light-emitting element 971 is, for example, an infrared light-emitting diode that emits infrared light. When the movement detection device 9 is attached to the presser bar 16 of the sewing machine 1, the light-emitting element 971 emits light downward. The emitted light passes through the opening 100, reaches the sewing object C, and is reflected. The light reflected by the sewing object C passes through the opening 100. The light-receiving element 972 is an element for detecting light reflected by the sewing object C within a detection area, and detects the light reflected from the sewing object C and converts it into an electrical signal. The detection area is located below the opening 100 and is a circular area in a plan view. The light-emitting element 971 is, for example, an infrared imaging element that detects infrared rays. The sensor 97 periodically irradiates light toward the sewing workpiece C using the light-emitting element 971, and detects the amount of movement of the sewing workpiece C per unit time. The movement detection device 9 of this embodiment detects the amount of movement in the short-side direction D1 and the amount of movement in the long-side direction D2. The movement detection device 9 detects the amount of movement in the short-side direction D1 by regarding the amount of movement toward the rear as a positive amount of movement and the amount of movement toward the front as a negative amount of movement. The movement detection device 9 detects the amount of movement in the long-side direction D2 by regarding the amount of movement toward the right as a positive amount of movement and the amount of movement toward the left as a negative amount of movement.

[0018] The cable 99 extends upward from the rear of the upper surface of the housing 95. The cable 99 is detachably connected to a connector (not shown) provided on the back of the arm 13. The movement detection device 9 outputs the movement amount of the sewing workpiece C per unit time to the sewing machine 1 via the cable 99. The attachment body 98 extends upward from the front of the upper surface of the housing 95. The attachment body 98 is detachably attached to the presser bar 16. As a result, the movement detection device 9 is detachably attached to the lower end of the presser bar 16.

[0019] In the sewing machine 1 having the above configuration, a brief description will be given of the operation when the sewing material is transported by the feed dog 32. When the sewing machine 1 detects that the start / stop switch 45 is pressed, it synchronously drives the shuttle mechanism, feed mechanism 31, needle bar mechanism, and presser foot mechanism. As a result, the sewing needle 17 attached to the needle bar 15 forms a stitch on the sewing material C placed on the bed surface 10.

[0020] The electrical configuration of the sewing machine 1 will be described with reference to Figure 4. The processor 3 of the sewing machine 1 includes a CPU 61, a ROM 62, a RAM 63, a storage device 64, and an input / output interface 65. The CPU 61 is connected to the ROM 62, the RAM 63, the storage device 64, and the input / output interface 65 via a bus 66.

[0021] The CPU 61 is responsible for main control of the sewing machine 1 and executes various calculations and processes related to sewing in accordance with various programs stored in the ROM 62. The ROM 62 has multiple storage areas, including a program storage area (not shown). The program storage area stores various programs for operating the sewing machine 1, including a program for executing the main processing described below. The RAM 63 has a storage area for storing the results of calculations performed by the CPU 61. The storage device 64 stores various parameters used by the sewing machine 1 to execute various processes. The storage device 64 stores the correspondence between the detection results of the encoder 38 (described below) and the up-down position of the needle bar 15, assuming that the angle of the main shaft 34 is 0 degrees when the needle bar 15 is at the top dead center. The storage device 64 stores the correspondence between the movement amount of the sewing workpiece C and the movement speed of the needle bar 15 in the sewing control processing described below.

[0022] The input / output interface 65 is connected to the drive circuits 91 to 94 of the processor 3, the touch screen 44, the start / stop switch 45, the encoder 38, and the light emitting element 971 and the light receiving element 972 of the sensor 97 of the movement detection device 9.

[0023] The drive circuit 91 is connected to the sewing machine motor 33. The drive circuit 91 drives the sewing machine motor 33 in accordance with a control signal from the CPU 61. As the sewing machine motor 33 is driven, the needle bar mechanism is driven via the main shaft 34 of the sewing machine 1, causing the needle bar 15 to reciprocate up and down. The sewing machine motor 33 moves the needle bar 15 up and down within a range that includes a needle-up position, where the lower end 18 of the sewing needle 17 is above the needle plate 41, and a needle-down position, where the lower end 18 of the sewing needle 17 is below the needle plate 41. The upper end of the movable range of the needle bar 15 is the top dead center, and the lower end is the bottom dead center. The drive circuit 92 is connected to the feed amount adjustment motor 30. The feed amount adjustment motor 30 rotates its output shaft to adjust the feed amount of the workpiece C in the front-to-rear direction by the feed mechanism 31. The drive circuit 93 drives the presser foot motor 35 in accordance with a control signal from the CPU 61. As presser motor 35 is driven, presser bar 16 moves up and down independently of the drive of main shaft 34 of sewing machine 1. Presser motor 35 moves presser bar 16 up and down within a range that includes a normal position and a lowered position where lower end 19 of presser bar 16 is lower than the normal position. The upper end of the movable range of presser bar 16 is a raised position that is higher than the normal position, and the lower end is a contact position where presser foot 25 contacts needle plate 41. Drive circuit 94 drives LCD 43 in accordance with a control signal from CPU 61 to display an image on LCD 43. Encoder 38 outputs a detection result corresponding to the rotation angle of sewing machine motor 33 to input / output interface 65.

[0024] The main processing of the sewing machine 1 will be described with reference to FIG. 5. In the main processing, with the movement detection device 9 attached to the presser bar 16, the start / stop switch 45 is selected at least either at the start or restart of sewing, and in response to the detection of a sewing instruction, the needle bar 15 is moved back and forth in the vertical direction based on the detection result of the movement detection device 9 to sew the workpiece C. When the processor 3 detects an instruction to execute the main processing, it reads a program for executing the main processing stored in the program storage area of ​​the ROM 62 into the RAM 63. The processor 3 executes the following steps in accordance with the instructions contained in the program read into the RAM 63. The program includes instructions for causing the processor 3 to execute the following processes. Various parameters required to execute the main processing are stored in the storage device 64. Various data obtained during the main processing is stored in the RAM 63 as appropriate. In the following description, steps are abbreviated as "S."

[0025] When the main process starts, the presser bar 16 is in the raised position, and the needle bar 15 is in the needle up stop position or the needle down position. The needle up stop position may be any position where the lower end 18 of the sewing needle 17 is above the needle plate 41. In this embodiment, this is the position where the angle of the main shaft 34 is 32 degrees and the needle bar 15 is slightly below the top dead center. The needle down position is a position where the lower end 18 of the sewing needle 17 is below the needle plate 41. In this embodiment, the angle of the main shaft 34 is 125 degrees and the lower end 18 of the sewing needle 17 is halfway from the position where it is flush with the needle plate 41 toward the bottom dead center. When the main process is being executed, the feed dog 32 is positioned so that its upper end is not above the needle plate 41. When the main process is being executed, the presser bar 16 does not move up and down in conjunction with the up and down movement of the needle bar 15, unlike when sewing using the feed dog 32.

[0026] In response to detection of a sewing command via start / stop switch 45, which is an input interface, processor 3 starts the main process, lowers presser bar 16, and executes first stitch processing, in which the needle bar 15 is moved from the needle down position to the needle up position, with the position where movement detection device 9 contacts the workpiece C defined as the lowered position and the position a predetermined distance above the lowered position defined as the normal position. Specifically, as shown in FIG. 2(B), processor 3 drives presser motor 35 to start lowering presser bar 16 (S1), and determines whether the thickness of workpiece C has been acquired based on the position where presser foot 25 contacts workpiece C (S2). If the thickness has not been acquired (S2: NO), processor 3 returns the process to S2. If the thickness has been acquired (S2: YES), processor 3 stops the lowering of presser bar 16 at the position where movement detection device 9 contacts presser foot 25 with workpiece C (S3).

[0027] Processor 3 determines whether needle bar 15 is in the needle down position based on the detection result of encoder 38 (S4). If needle bar 15 is in the needle down position (S4: YES), processor 3 drives sewing machine motor 33 to raise needle bar 15 at an ascending speed (S5). The ascending speed may be a preset speed, for example, 70 rpm.

[0028] The processor 3 determines whether the rotation angle of the main shaft 34 has reached a predetermined angle based on the detection result of the encoder 38 (S6). The predetermined angle is the angle at which the lower end 18 of the sewing needle 17 is at the needle up position above the needle plate 41. In this embodiment, the needle up position is the position at which the lower end 18 of the sewing needle 17 is above the needle plate 41 and above the top surface of the sewing workpiece C. The needle up position may be set based on the thickness of the sewing workpiece C obtained in S2, or may be a value set based on the maximum thickness of the sewing workpiece that is normally sewn.

[0029] If the rotation angle of the main shaft 34 has not reached the predetermined angle (S6: NO), the processor 3 returns the process to S6. If the rotation angle of the main shaft 34 has reached the predetermined angle (S6: YES), the processor 3 starts raising the presser bar 16 (S7). The processor 3 determines whether the presser bar 16 has reached its normal position based on the drive amount of the presser motor 35 from S7 (S8). As shown in FIG. 2(C), after obtaining the thickness of the sewing workpiece C, the processor 3 drives the presser motor 35 to set the normal position to a predetermined distance above the position where the presser foot 25 contacts the sewing workpiece C. The predetermined distance is set to a value between 1 mm and 4 mm, for example.

[0030] If presser bar 16 has not reached the normal position (S8: NO), processor 3 returns the process to S8. If presser bar 16 has reached the normal position (S8: YES), processor 3 ends the raising of presser bar 16. Through the processes of S5 to S9, processor 3 drives sewing machine motor 33 to move needle bar 15 from the needle down position to the needle up position (S6: YES) at least either when starting sewing or when resuming sewing, and then drives presser motor 35 to execute first stitch processing to move presser bar 16 from the lowered position to the normal position (S7). Through the first stitch processing, lower end 18 of sewing needle 17 is positioned above the top surface of the sewing workpiece C, and presser foot 25 is positioned above the top surface of the sewing workpiece C, allowing the user to smoothly move the sewing workpiece C in the horizontal direction.

[0031] Processor 3 acquires the amount of movement of workpiece C based on the detection result of movement detection device 9 acquired after presser bar 16 has moved to the normal position, or the detection result of movement detection device 9 acquired after needle bar 15 has moved to a predetermined position where lower end 18 of sewing needle 17 is above needle plate 41 (S10). The predetermined position may be any position where lower end 18 of sewing needle 17 is above needle plate 41. The predetermined position is preferably the same vertical position as the needle up position or a position above the needle up position.

[0032] Processor 3 determines whether the absolute value of the movement amount acquired in S10 is greater than a predetermined amount (S11). The predetermined amount may be set to a value equal to or greater than 0, taking into consideration the detection accuracy of movement detection device 9, etc. In this embodiment, movement detection device 9 detects both the movement amount in the short-side direction D1 and the movement amount in the long-side direction D2. Therefore, processor 3 may determine, for example, whether the absolute value of at least one of the movement amounts is greater than a predetermined amount. Processor 3 may calculate the length of a vector based on each of the movement amount in the short-side direction D1 and the movement amount in the long-side direction D2 as the movement amount, and determine whether the calculated movement amount is greater than a predetermined amount. If the absolute value of the movement amount is not greater than the predetermined amount (S11: NO), processor 3 determines whether needle bar 15 is at the needle up stop position based on the detection result of encoder 38 (S19).

[0033] If needle bar 15 is not at the needle up stop position (S19: NO), processor 3 returns the process to S11. If needle bar 15 is at the needle up stop position (S19: YES), processor 3 stops driving sewing machine motor 33 and stops needle bar 15 at the needle up stop position (S20). Processor 3 determines whether needle bar 15 has been stopped for a predetermined time or more (S21). If needle bar 15 has not been stopped for a predetermined time or more (S21: NO), processor 3 returns the process to S11. If needle bar 15 has been stopped for a predetermined time or more (S21: YES), processor 3 moves needle bar 15 to the needle down position (S22). Processor 3 then ends the main process.

[0034] If the movement distance is greater than the predetermined distance (S11: YES), processor 3, based on the detection result of movement detection device 9, drives sewing machine motor 33 to execute second stitch processing, which moves needle bar 15 up and down with presser bar 16 in the normal position (S12). That is, in the second stitch processing, if processor 3 determines that the workpiece C has moved more than the predetermined distance based on the detection result of movement detection device 9 obtained after presser bar 16 has moved to the normal position in the first stitch processing (S11: YES), processor 3 starts processing to move needle bar 15 up and down at a predetermined speed with presser bar 16 in the normal position (S12). The predetermined speed may be the same as the rising speed in S5, or may be different. The predetermined speed is, for example, 400 rpm. Processor 3 then determines whether a stop command has been detected (S13). When the user wishes to end or interrupt sewing, he or she presses start / stop switch 45 to input a stop command. If a stop command is detected (S13: YES), processor 3 controls sewing machine motor 33 based on the detection result of encoder 38 to stop needle bar 15 at the needle down position (S18). If a stop command is not detected (S13: NO), processor 3 determines whether the movement amount is greater than a predetermined amount (S14). The predetermined amount in S14 may be the same as or different from S11.

[0035] If the movement amount is greater than the predetermined amount (S14: YES), the processor 3 performs sewing control processing (S16) based on the correspondence between the movement amount of the sewing workpiece C stored in the memory device 64 and the movement speed of the needle bar 15, and after the second stitch processing in S12, based on the detection result of the movement detection device 9, drives the sewing machine motor 33 to move the needle bar 15 in the vertical direction at a speed corresponding to the movement amount of the sewing workpiece C.

[0036] During the sewing control process, if the movement amount of the sewing workpiece C is equal to or less than a predetermined amount based on the detection result of movement detection device 9 (S14: NO), needle bar 15 is stopped at the needle up stop position (S15). The needle up stop position in S15 may be the same as the needle up stop position in S20, or they may be different. Processor 3 determines whether needle bar 15 has stopped at the needle up stop position for a predetermined time (S17). The predetermined time in S17 may be the same as the predetermined time in S21, or they may be different. If needle bar 15 has not stopped at the needle up stop position for the predetermined time (S17: NO), processor 3 returns the process to S13. If needle bar 15 has stopped at the needle up stop position for the predetermined time (S17: YES), processor 3 controls sewing machine motor 33 based on the detection result of encoder 38 to move needle bar 15 to the needle down position (S22). Processor 3 then ends the main process.

[0037] 5 to 7, an evaluation test will be described using a comparative example in which the sewing machine 1 performs a conventional sewing process based on the detection results of the movement detection device 9, and an example in which the sewing machine 1 performs the above-mentioned main process. FIGS. 6 and 7 show the movement amount per unit time of the workpiece C, the up-down position of the needle bar 15, and the up-down position of the presser bar 16, based on the detection results of the movement detection device 9 when sewing starts or resumes. In the movement amounts shown in FIGS. 6 and 7, the movement amount per unit time of the workpiece C in the short direction D1 detected by the movement detection device 9 is indicated by a solid line, and the movement amount in the long direction D2 is indicated by a dotted line. At the start of the evaluation test, the presser bar 16 is in the raised position, and the needle bar 15 is in the needle down position.

[0038] As shown in FIG. 6, when performing the sewing process of the comparative example, the sewing machine 1 detects a sewing command at timing T1, and then drives the presser motor 35 to start lowering the presser bar 16. After obtaining the thickness of the workpiece C based on the position where the workpiece C comes into contact with the presser foot 25, the sewing machine 1 stops the lowering of the presser bar 16. The sewing machine 1 then raises the presser bar 16 to its normal position so that the workpiece C can be manually moved horizontally. The raising of the presser bar 16 creates a vertical gap of several millimeters between the presser foot 25 and the movement detection device 9 and the workpiece C. At timing T2, with the presser bar 16 in its normal position, the sewing machine 1 raises the needle bar 15 toward the needle up stop position. When the tip of the sewing needle 17 comes out of the workpiece C during the process of raising the needle bar 15, the part of the workpiece C that the sewing needle 17 had been stuck in rises together with the sewing needle 17, and moves up and down between the needle plate 41, the presser foot 25 and the movement detection device 9. During periods T3 and T4, the movement detection device 9 detects the movement of the workpiece C at this time, and based on the detection result of the movement detection device 9, the sewing machine 1 does not stop the needle bar 15 at the needle up stop position, but continues to drive the sewing machine motor 33, and sews the second stitch.

[0039] 5 and 7, when the main processing of the embodiment is executed, in response to detection of a sewing command at timing T1 in the main processing, the sewing machine 1 drives the presser motor 35 to start lowering the presser bar 16 (S1), obtains the thickness of the workpiece C based on the position where the workpiece C comes into contact with the presser foot 25 (S2: YES), and then stops the lowering of the presser bar 16 (S3). Before raising the presser bar 16 to its normal position, the sewing machine 1 drives the sewing machine motor 33 at timing T5 (S4: YES, S5) to raise the needle bar 15. Even when the tip of the sewing needle 17 comes out of the workpiece C during the process of raising the needle bar 15, the presser foot 25 and the housing 95 of the movement detection device 9 are pressing down on the workpiece C from above, so the portion of the workpiece C where the sewing needle 17 had been inserted does not rise with the sewing needle 17. Therefore, movement detection device 9 does not detect movement of workpiece C even when the tip of sewing needle 17 comes out of workpiece C. Sewing machine 1 starts raising presser bar 16 at timing T6 when needle bar 15 reaches the needle up position (S7). Based on the detection result of movement detection device 9 acquired after presser bar 16 has moved to the normal position at timing T12, or the detection result of movement detection device 9 acquired after needle bar 15 has moved to a predetermined position at timing T6 where lower end 18 of sewing needle 17 is above needle plate 41, movement detection device 9 does not detect movement of workpiece C during period T9 (S11: NO), so sewing machine 1 controls sewing machine motor 33 based on the detection result of encoder 38 to stop needle bar 15 at the needle up stop position at timing T7 (S20). The sewing machine 1 continues to stop at the needle up stop position based on the detection result of the movement detection device 9 during period T10 (S11: NO), and then starts moving the needle bar 15 up and down at timing T8 based on the detection result of the movement detection device 9 during period T11 (S11: YES) (S12).

[0040] From the results of the above evaluation test, it was confirmed that by having the sewing machine 1 execute the main processing when starting or resuming sewing based on the detection results of the movement detection device 9 from a state in which the needle bar 15 is in the needle down position, it is possible to prevent the sewing material C from floating up and contribute to reducing the possibility of unintended behavior by the user.

[0041] In the above embodiment, the sewing machine 1 is an example of a sewing machine of the present invention. The processor 3 is an example of a processor of the present invention. The movement detection device 9 is an example of a movement detection device of the present invention. The needle bar 15 is an example of a needle bar of the present invention. The presser bar 16 is an example of a presser bar of the present invention. The sewing needle 17 is an example of a sewing needle of the present invention. The sewing machine motor 33 is an example of a sewing machine motor of the present invention. The presser motor 35 is an example of a presser motor of the present invention. The needle plate 41 is an example of a needle plate of the present invention. The needle hole 40 is an example of a needle hole of the present invention. The sewing workpiece C is an example of a sewing workpiece of the present invention. The start / stop switch 45 is an example of an input interface of the present invention. The processing of S15 is an example of a stop processing of the present invention. The processing of S5 to S9 is an example of a first stitch processing of the present invention. The processing of S12 is an example of a second stitch processing of the present invention. The processing of S16 is an example of a sewing control processing of the present invention.

[0042] The sewing machine 1 of the above embodiment includes a needle bar 15, a needle plate 41, a presser bar 16, a sewing machine motor 33, a presser motor 35, and a processor 3. The needle bar 15 extends vertically. The needle plate 41 has a needle eye 40 through which a sewing needle 17 attached to the needle bar 15 can be inserted. The presser bar 16 extends vertically and is equipped with a movement detection device 9 that detects movement of a sewing workpiece C placed on the needle plate 41. The sewing machine motor 33 moves the needle bar 15 vertically within a range that includes a needle-up position where the lower end 18 of the sewing needle 17 is above the needle plate 41 and a needle-down position where the lower end 18 of the sewing needle 17 is below the needle plate 41. The presser motor 35 moves the presser bar 16 vertically within a range that includes a normal position and a lowered position where the lower end 19 of the presser bar 16 is lower than the normal position. At least at the start of sewing or the restart of sewing, processor 3 drives sewing machine motor 33 to move needle bar 15 from the needle down position to the needle up position, and then drives presser motor 35 to execute first stitch processing, which moves presser bar 16 from the lowered position to the normal position (S5 to S9). Based on the detection result of movement detection device 9, processor 3 executes second stitch processing, which moves needle bar 15 up and down with presser bar 16 in the normal position (S12). The first stitch processing executed by processor 3 of sewing machine 1 contributes to the movement detection device 9 restricting upward movement of the sewing workpiece C when the needle 17 pulls upward on the sewing workpiece C as the needle bar 15 moves from the lowered position to the normal position, compared to when presser bar 16 is in the normal position at the start of sewing or the restart of sewing. The first stitch processing of sewing machine 1 contributes to preventing the second stitch from being erroneously sewn based on the detection result of movement detection device 9 during execution of the first stitch processing.

[0043] The needle up position is a position where the lower end 18 of the sewing needle 17 is higher than the needle plate 41 and higher than the top surface of the workpiece C. Compared to a case where the presser bar 16 is moved from the lowered position to the normal position before the needle bar 15 moves to a position where the lower end 18 of the sewing needle 17 is higher than the top surface of the workpiece C, the first stitch processing executed by the processor 3 of the sewing machine 1 contributes to the movement detection device 9 restricting the upward movement of the workpiece C when the sewing needle 17 pulls the workpiece C upward as the needle bar 15 moves from the lowered position to the normal position.

[0044] In the second stitch processing, if the workpiece C has moved more than a predetermined amount based on the detection result of movement detection device 9 obtained after presser bar 16 has moved to its normal position in the first stitch processing (S11: YES), processor 3 moves needle bar 15 up and down at a predetermined speed with presser bar 16 in its normal position (S12). The second stitch processing executed by processor 3 of sewing machine 1 contributes to preventing the second stitch from being erroneously sewn based on the detection result of movement detection device 9 when the first stitch processing is executed, compared to when the second stitch is sewn based on the detection result of movement detection device 9 obtained before presser bar 16 has moved to its normal position.

[0045] In the second stitch processing, if the workpiece C has moved more than a predetermined amount based on the detection result of movement detection device 9 obtained after needle bar 15 has moved to a predetermined position where lower end 18 of sewing needle 17 is above needle plate 41 in the first stitch processing (S11: YES), processor 3 moves needle bar 15 up and down at a predetermined speed with presser bar 16 in the normal position (S12). The second stitch processing executed by processor 3 of sewing machine 1 contributes to preventing the second stitch from being erroneously sewn based on the detection result of movement detection device 9 when the first stitch processing is executed, compared to when the second stitch is sewn based on the detection result of movement detection device 9 obtained before needle bar 15 moves to the movement position.

[0046] After processing the second stitch, processor 3 executes a sewing control process in which, based on the detection result of movement detection device 9, processor 3 drives sewing machine motor 33 to move needle bar 15 up and down at a speed corresponding to the amount of movement of the sewing workpiece C (S16). During the sewing control process, if the amount of movement of the sewing workpiece C is equal to or less than a predetermined amount based on the detection result of movement detection device 9, processor 3 executes a stop process in which processor 3 stops driving sewing machine motor 33 at the needle up stop position where bottom end 18 of needle 17 is above needle plate 41, thereby stopping needle bar 15 (S15). The stop process executed by processor 3 of sewing machine 1 stops needle bar 15 at the needle up stop position, which contributes to a smooth resumption of sewing from the state where sewing was interrupted.

[0047] In processing the first stitch, processor 3 lowers presser bar 16, defining the position where movement detection device 9 abuts against the workpiece C as the lowered position, and the normal position as a position a predetermined distance above the lowered position, and after moving needle bar 15 from the needle down position to the needle up position (S6: YES), moves presser bar 16 from the lowered position to the normal position (S7 to S9). Compared to when movement detection device 9 does not abut against the workpiece C at the lowered position, the first stitch processing executed by processor 3 of sewing machine 1 contributes to limiting the upward movement of movement detection device 9 when sewing needle 17 pulls the workpiece C upward as needle bar 15 moves from the lowered position to the normal position.

[0048] The sewing machine 1 includes a start / stop switch 45 as an input interface. The processor 3 executes the first stitch process in response to detection of a sewing instruction via the input interface. The first stitch process of the sewing machine 1 helps to prevent the first stitch process from being executed at a timing unintended by the user.

[0049] The present invention is not limited to the above embodiment and various modifications are possible. The sewing machine 1 may be a dedicated sewing machine using the movement detection device 9. In that case, the feed amount adjustment motor 30, the feed mechanism 31, and the feed dog 32 may be omitted. The sewing machine 1 may include the movement detection device 9, or the movement detection device 9 may be omitted. The movement detection device 9 is attached to the presser bar 16 and may detect the movement of the workpiece C placed on the needle plate 41, and its configuration, shape, etc. may be modified as appropriate. The movement detection device 9 may be built into the sewing machine 1. In that case, for example, a configuration equivalent to the movement detection device 9 may be built into the bed 11 or the head 14. The movement detection device 9 may be capable of detecting the movement of the workpiece C; it need not be capable of detecting the amount of movement of the workpiece C, and may be capable of detecting only the amount of movement of the workpiece C in either the short-side direction D1 or the long-side direction D2, or may be capable of detecting the amount of movement in the horizontal direction. The detection result of the movement detection device 9 may indicate only the amount of movement of the sewing workpiece C, and may not necessarily indicate the direction of movement.

[0050] The input interface may be any device or method capable of inputting information into the processor 3, including pointing devices such as a keyboard, mouse, trackball, touchpad, graphics tablet, scanner, touch screen integrated into the display, audio input devices such as a voice recognition system, and other types of input devices such as a microphone.

[0051] The program including the instructions for executing the main processing of Fig. 5 may be stored in the storage device of each device before the processor 3 executes the program. Therefore, the program acquisition method, acquisition path, and device for storing the program may each be changed as appropriate. The program executed by the processor 3 may be received from another device via a cable or wireless communication and stored in a storage device. The other device may include, for example, a PC and a server connected via a network.

[0052] The steps of the main processing are not limited to being executed by the processor 3, and some or all of them may be executed by other electronic devices (e.g., ASIC). The steps of the main processing may be distributed among multiple electronic devices (e.g., multiple CPUs). The order of the steps of the main processing may be changed, and steps may be omitted or added as necessary. The following modifications may be made to the main processing as appropriate.

[0053] The method of acquiring the thickness of the sewing workpiece C may be changed as appropriate, or the processor 3 may place the presser bar 16 in the lowered position without acquiring the thickness of the sewing workpiece C. The lowered position and the normal position may be changed as appropriate. The lowered position may be the position where the presser foot 25 contacts the sewing workpiece C, or may be a position several millimeters above the position where the presser foot 25 contacts the sewing workpiece C. The needle up position may be a position where the lower end 18 of the sewing needle 17 is above the needle plate 41, or may be a position where the lower end 18 of the sewing needle 17 is below the top surface of the sewing workpiece C. The needle up position may be the same vertical position as the needle up stop position, or may be above the needle up stop position, or may be the top dead center. The normal position may be above the lowered position and may be the same position regardless of the lowered position. The needle down position and the needle up stop position may be changed as appropriate. The processing of S8 may be executed based on the detection result of an encoder that detects the drive amount of presser motor 35, or may be executed based on the detection result of a position sensor that detects the vertical position of presser bar 16.

[0054] In processing the second stitch, processor 3 may move needle bar 15 up and down at a predetermined speed or a speed corresponding to the amount of movement of the workpiece C while presser bar 16 is in the normal position, based on the detection result of movement detection device 9 obtained before presser bar 16 moves to the normal position. In processing the second stitch, processor 3 may move needle bar 15 up and down at a predetermined speed while presser bar 16 is in the normal position, based on the detection result of movement detection device 9 obtained before needle bar 15 moves to the needle up position. Processor 3 may execute at least one of processing the second stitch and sewing control processing for needle bar 15 based on the detection result of movement detection device 9 during the period when lower end 18 of sewing needle 17 is above needle plate 41. If movement detection device 9 always outputs a positive value, processor 3 may determine in S11 and S14 whether the amount of movement is greater than a predetermined amount.

[0055] After processing the second stitch, processor 3 may move needle bar 15 up and down at a predetermined speed based on the detection result of movement detection device 9, regardless of the amount of movement of the workpiece C. Processor 3 may determine whether the absolute value of the amount of movement is equal to or greater than a predetermined amount in S11 and S14. During the sewing control process, processor 3 may omit the stop process of stopping needle bar 15 at the needle up stop position if the amount of movement of the workpiece C is equal to or less than a predetermined amount based on the detection result of movement detection device 9. In this case, sewing machine 1 may stop needle bar 15, for example, when a stop command is detected. Processor 3 may stop needle bar 15 at the needle down position instead of the needle up stop position in the stop process. In this case, the stop process executed by processor 3 of sewing machine 1 stops needle bar 15 at the needle down position, which contributes to making it easier to change the orientation of workpiece C with needle 17 inserted into it while sewing is paused. Processor 3 may stop needle bar 15 at any position in the stop process. Sewing machine 1 may automatically execute the first stitch processing after a predetermined time has elapsed with needle bar 15 in the needle down position, without detecting a sewing instruction.

[0056] The above-mentioned modifications may be combined as appropriate within the scope of the claims. The applicant intends to obtain patent rights for not only the combinations exemplified in the claims, but also for other combinations that do not deviate from the gist of the present invention and do not cause any contradictions. [Explanation of symbols]

[0057] 1: sewing machine, 3: processor, 9: movement detection device, 15: needle bar, 16: presser bar, 17: sewing needle, 33: sewing machine motor, 35: presser motor, 40: needle hole, 41: needle plate, 45: start / stop switch, C: sewing object

Claims

1. A needle bar extending in the vertical direction; a needle plate having a needle hole formed therein through which the sewing needle attached to the needle bar can be inserted; a presser bar extending in the vertical direction and having a movement detection device attached thereto that detects movement of a sewing workpiece placed on the needle plate; a sewing machine motor that moves the needle bar in the up and down direction within a range that includes a needle up position where the lower end of the sewing needle is above the needle plate and a needle down position where the lower end of the sewing needle is below the needle plate; a presser motor that moves the presser bar in the up and down direction within a range that includes a normal position and a lowered position where the lower end of the presser bar is lower than the normal position; Processor and Equipped with The processor: a first stitch process in which, at least either at the start of sewing or at the restart of sewing, the sewing machine motor is driven to move the needle bar from the needle down position to the needle up position, and then the presser motor is driven to move the presser bar from the lowered position to the normal position; a second stitch process in which the sewing machine motor is driven based on the detection result of the movement detection device to move the needle bar in the up and down direction with the presser bar in the normal position; A sewing machine configured to perform the following.

2. 2. The sewing machine according to claim 1, wherein the needle up position is a position where the lower end of the sewing needle is above the needle plate and above the top surface of the workpiece.

3. The processor:

2. The sewing machine according to claim 1, wherein, in the second stitch processing, if the workpiece has moved more than a predetermined amount based on the detection result of the movement detection device obtained after the presser bar has moved to the normal position in the first stitch processing, the needle bar is moved in the vertical direction at a predetermined speed while the presser bar is in the normal position.

4. The processor:

2. The sewing machine according to claim 1, wherein, in the second stitch processing, if the workpiece has moved more than a predetermined amount based on the detection result of the movement detection device obtained after the needle bar has moved to the needle up position in the first stitch processing, the needle bar is moved in the vertical direction at a predetermined speed while the presser bar is in the normal position.

5. The processor: a sewing control process for driving the sewing machine motor to move the needle bar in the vertical direction at a speed corresponding to the amount of movement of the workpiece based on the detection result of the movement detection device after the second stitch processing; 2. The sewing machine according to claim 1, wherein, during the sewing control process, if the movement amount of the workpiece is equal to or less than a predetermined amount based on the detection result of the movement detection device, a stop process is performed in which the driving of the sewing machine motor is stopped at a needle up stop position where the lower end of the sewing needle is above the needle plate, and the needle bar is stopped.

6. The processor:

2. The sewing machine according to claim 1, wherein, in the first stitch processing, the presser bar is lowered, and the position where the movement detection device abuts against the workpiece is defined as the lowered position, and a position a predetermined distance above the lowered position is defined as the normal position, and after the needle bar is moved from the needle down position to the needle up position, the presser bar is moved from the lowered position to the normal position.

7. further comprising an input interface; The processor:

2. The sewing machine according to claim 1, wherein the first stitch processing is executed in response to a sewing instruction being detected via the input interface.

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