JP3233673U - Rotation axis detection device for sewing machine motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation axis detecting device for a sewing machine motor in which the operation of the sewing machine becomes more accurate and the production efficiency and the yield are improved. A rotation axis detection device for a sewing machine motor includes a magnet turntable 20, a first IC board 30, and a second IC board 40. The magnet turntable is magnetized in the inner ring magnetic region, the outer ring magnetic region, and the upper positioning magnetic region. Through the first IC board, the rotation of the magnet turntable is detected and the rotation of the rotating shaft is directly captured, and in order to control the operation of the motor 10, the inner ring magnetic region is detected and the R, S, T pulses are detected. The signal is output, the outer ring magnetic region is detected, and the A and B pulse signals are output. The rotation of the magnet turntable is detected via the second IC board, and the rotation of the rotation axis is directly captured by the sewing machine. In order to control the stop position of the upper positioning needle, the upper positioning magnetic region is detected and the upper positioning pulse signal is output. [Selection diagram] Fig. 2

Description

The present invention relates to a motor rotating shaft detecting device for accurately monitoring the operating state of the motor rotating shaft, and particularly to a sewing machine motor rotating shaft detecting device.

Current sewing machine encoders are classified into two types, contact type and non-contact type. Contact encoders have the problem of component wear, and in order to avoid contact wear, non-contact encoders such as optical encoders and magnetic encoders have been developed in related industries.

Taiwan Utility Model No. M302831 Taiwan Utility Model No. M473407 Gazette

As a servomotor encoder, for example, the one described in Patent Document 1 is known.
The encoder described in Patent Document 1 is an optical encoder. Servomotor encoders include a shading sheet and a detector, a light-shielding sheet is a circular sheet body used to combine with the rear end of the servomotor shaft, and the outer or inner ring has multiple notches at equal intervals. The concentric ring of the inner ring or the outer ring is provided with a plurality of light-transmitting holes, the detection device is provided with a base combined with the rear end surface of the servomotor, the base is provided with a bottom plate having perforations, and the bottom plate is provided. An insert body that forms an arc shape and surrounds the light-shielding sheet is provided at a position extending outward in the vertical direction from the peripheral edge, and is surrounded by the insert body, and has three photo interrupters for detecting a notch and each light transmission. Combine a photo encoder module to detect holes. Thereby, the photo interrupter and the photo encoder module can detect the position and movement of the shading sheet, and the information is encoded and output in order to detect and control the operation of the servomotor.

The above-mentioned optical encoder is a rotary optical encoder that is generally used in sewing machines in the industry at present. However, since the operation mechanism of the sewing machine is to sew the fabric, thread breakage or thread breakage occurs in the sewing process. A large amount of lint is generated, and these lint breaks and lint adhere to the perforations of the bottom plate and the translucent holes of the light-shielding sheet, further affect the detection accuracy of the photo interrupter, and cause a timing error of the sewing machine.

In the non-contact encoder, the magnetic encoder has the advantage of overcoming the problem of wear of the contact encoder parts, and converts the mechanical angle of the rotating shaft into a digital or analog signal to convert the angle, linear displacement, rotation speed, etc. Compared to rotary optical encoders, magnetic encoders are used to achieve signal output in harsh working environments such as oil, dust, or the aforementioned sewing machine thread breaks and lint. There is no problem that affects the detection accuracy. Therefore, if the magnetic encoder can be applied to the sewing machine, the problems faced by the above-mentioned optical encoder will be solved.

As the magnetic encoder, for example, the synchronization device between the direct drive motor of the sewing machine and the magnetic encoder described in Patent Document 2 relates to the synchronization device between the direct drive motor of the sewing machine and the magnetic encoder. The main technical method is to sleeve the transmission gear on the output shaft of the motor, provide a mounting sheet on the housing of the motor to attach additional shafts, and sleeve the driven gear on the shaft to attach the transmission gear. The driven gear meshes with the transmission belt, then a magnetic component is provided on the shaft, a sensor is provided corresponding to the path through which the magnetic component passes, and the shaft is of the motor when the motor is rotating. Due to the transmission relationship of the output shaft, transmission gear, transmission belt, and driven gear, the magnetic components rotate together with the shaft, and at this time, the sensor responds to changes in the magnetic field of the rotating magnetic component. , The necessary data can be measured. That is, most prior art adds a transmission mechanism to the output shaft to indicate the rotational state of another driven shaft, and then uses the shaft to rotate the magnetic component for monitoring and control. And generate the code.

However, the technical means of transmitting additional shafts by adding a transmission mechanism are unnecessary output loss and transmission loss, belt wear and dust, belt transmission slippage, transmission gap due to belt wear, and belt. When a unilateral force is applied to the contact position, many problems such as rotational resonance are likely to occur, which causes a problem of detection distortion. Furthermore, problems such as excessive occupation of the motor placement space and heat dissipation occur, magnetic parts cannot directly perform physical level adjustment operations, and positioning deviations need to be corrected and adjusted by electronic parameter settings. There is. In addition, it is difficult for those who are unfamiliar with the control function to start using it, and setting errors tend to affect the yield of products. Therefore, optimization and improvement of the rotation axis detection device of the sewing machine motor is the focus of the present invention.

The present invention has been made in view of the above, and the purpose of the present invention is to directly detect the rotation axis of a sewing machine motor using a dual sensing IC board to make the operation of the sewing machine more accurate, and further to produce efficiency and yield. The purpose is to provide a rotation axis detection device for a sewing machine motor.

In order to achieve the above object, the rotation axis detection device of the technical means adopted by the present invention includes a magnet turntable and a first IC board, and the magnet turntable is fixed to the rotation shaft. The magnet turntable is magnetized in the inner ring magnetic region and the outer ring magnetic region, and the first IC board is described. The magnet turntable is fixed to the rear lid in order to detect the inner ring magnetic region and the outer ring magnetic region, output R, S, and T pulse signals, and output A and B pulse signals, respectively. Since it is directly fixed to the rotating shaft and rotates in synchronization with the rotating shaft, the absolute position of the rotating shaft can be detected and the generated signal is not distorted.

The rotation axis detection device includes a second IC board, and the magnet turntable includes the inner ring magnetic region and the outer ring magnetism in order to output the corresponding detection and upper positioning pulse signals by the second IC board. An upper positioning magnetic region is provided between the region and the region, and the operation of the motor is controlled in combination with the pulse signal output from the first IC board.

The rotation axis detection device is provided with a positioning mechanism on the rear lid, the positioning mechanism is provided with a second IC board, and the magnet turntable is a corresponding detection by the second IC board and an upper positioning pulse signal. An upper positioning magnetic region is provided between the inner ring magnetic region and the outer ring magnetic region, and the operation of the motor is controlled in combination with the pulse signal output from the first IC board.

The rear lid is provided with at least one first stud for fixing the first IC board, and the positioning mechanism corresponds to the first stud for the first stud to pass through. A first opening is provided, a plurality of lugs are provided on the peripheral edge of the positioning mechanism, and an adjusting hole for locking is provided at each of the lugs. When loosened, the positioning mechanism is rotated to rotate the positioning mechanism. The relative position of the second IC board and the upper positioning magnetic region can be adjusted and is rotated relative to the first stud through the first opening, and the positioning mechanism has a boss. A concave groove is formed between the boss and each of the lugs, and the turntable lid can be fitted into the concave groove.

A plurality of lugs are provided on the peripheral edge of the positioning mechanism, and an adjusting hole for locking is provided at each of the lugs. When loosened, the positioning mechanism is rotated to rotate the second IC board and the upper portion. The relative position with respect to the positioning magnetic region can be adjusted, the positioning mechanism has a boss, a recess is formed between the boss and each of the lugs, and the turntable lid is fitted into the recess. Can be done.

The rotation axis detection device includes a turntable lid, and the turntable lid is sleeved inside a ring groove of the rotation axis to cover the outside of the magnet turntable and the first IC board. It is fixed to the back lid.

The rotation axis detecting device includes a turntable lid, and the turntable lid covers the outside of the magnet turntable, the first IC board, and the second IC board and is fixed to the rear lid.

The inner ring magnetic region of the magnet turntable is magnetized at at least four poles according to the polarity arrangement to be detected by the first IC board.

The outer ring magnetic region of the magnet turntable is magnetized with twice the number of poles according to the polarity arrangement because it is detected by the first IC board. The number of poles in the outer ring magnetic region is 60 poles.

The upper positioning magnetic region of the magnet turntable is magnetized at three poles according to either the NSN polarity or the SNS polarity arrangement to be detected by the first IC board.

The magnet turntable is provided with a lower positioning magnetic region at a position 180 degrees opposite to the upper positioning magnetic region, and the second IC board detects the lower positioning magnetic region accordingly and a lower positioning pulse. It outputs a signal and controls the stop position of the lower positioning needle of the sewing machine. The magnet turntable has a non-magnetic region, the height of the non-magnetic region is smaller than the height of the lower positioning magnetic region, and the height of the non-magnetic region is 0.2 to 0. The height reduced to 6 mm and the area without magnetic poles is 0.4 mm.

The magnet turntable has a magnetic pole-less region, and the height of the magnetic pole-less region is smaller than the height of the inner ring magnetic region, the outer ring magnetic region, and the upper positioning magnetic region, and the magnetic pole-less region. The height of the region is reduced from 0.2 to 0.6 mm, and the reduced height of the non-magnetic region is 0.4 mm.

The material of the magnet turntable is a plastic material and an iron oxide magnet.

The rotation axis detection device has a hand wheel fixed to the rotation axis.

It is a perspective view which shows the embodiment of this invention. It is an exploded perspective view of the Embodiment of this invention. It is an exploded perspective view of the Embodiment of this invention. It is a figure which shows the magnetic region of the magnet turntable in embodiment of this invention. It is a figure which shows another magnetic region of the magnet turntable in embodiment of this invention. It is sectional drawing of embodiment of this invention. It is a figure which shows the positioning mechanism before rotation in embodiment of this invention. It is a figure which shows the positioning mechanism after rotation in embodiment of this invention. It is an exploded perspective view which uses the 1st IC board in embodiment of this invention.

As shown in FIGS. 1 to 3, the embodiment of the present invention is shown, and the rotation axis detection device of the sewing machine motor is provided corresponding to the position of the rotation axis 11 of the motor 10, and includes a magnet turntable 20 and a first. IC board 30, a second IC board 40, a positioning mechanism 50, and a turntable lid 60 are included.

As shown in FIG. 3, the motor 10 is provided with a first stud 121 on the rear lid 12, and one side of the positioning mechanism 50 main body has a boss 51 having a smaller area than the main body, and the boss 51 Is provided with a central hole 52 to be penetrated, and a first opening 53 is provided at a position corresponding to each first stud 121 and at a position corresponding to the first stud 121 for the first stud 121 to pass through. Is provided. The number of first studs 121 can also be increased or decreased on the premise that it is sufficient to lock the first IC board 30.

The positioning mechanism 50 extends outward from the peripheral edge of the main body to provide a plurality of lugs 54, forms a concave groove 55 between the boss 51 and the lugs 54, and forms each lug 54 as shown in FIG. A long arc-shaped adjusting hole 541 is provided to be penetrated. In the present embodiment, the positioning mechanism 50 has three lugs 54, and the lugs 54 can be increased or decreased according to demand.

At the time of assembly, in the positioning mechanism 50, the rotating shaft 11 is inserted into the center hole 52, the first stud 121 is inserted into the first opening 53, and finally the screw 56 is inserted into the adjusting hole 541. The positioning mechanism 50 is fixed to the rear lid 12.

The first IC board 30 is fixed to the first stud 121 penetrating the first opening 53 with a screw 31, and the second IC board 40 is screwed to the second stud 57 of the positioning mechanism 50 with a screw 41. It is fixed.

The positioning mechanism 50 according to the present embodiment has a pair of second studs 57 for locking the second IC board 40, and the position of the second stud 57 is also changed or, if necessary, the position of the second stud 57 is changed. As shown in FIG. 3, the second stud 57 is pre-installed at different angles for use in an optional manner. The number of second studs 57 can also be increased or decreased on the premise that it is sufficient to lock the second IC board 40.

The magnet turntable 20 has a disk-shaped main body, and a flange 21 is formed in the main body so as to surround the central circular hole 211. The magnet turntable 20 of the present embodiment is made of a plastic material and an iron oxide magnet, but the materials are not limited thereto.

When assembling, one side of the magnet turntable 20 and the gap adjuster 22 penetrate the rotating shaft 11 together, and then the C-shaped buckle 23 buckles corresponding to the ring groove 111 of the rotating shaft 11. Is fixed to the rotating shaft 11 as shown in FIG. 5, and on the other side, a flange 21 for sleeve the turntable lid 60 is provided, whereby the magnet turntable 20 is attached to the rotating shaft 11. It is clamped between the ring groove 111 and the turntable lid 60.

After the turntable lid 60 is inserted into the rotating shaft 11, the first stud 121 passes through the magnet turntable 20, the positioning mechanism 50, the second IC board 40 on the second stud 57, and the positioning mechanism 50. All of the first IC boards 30 on the top are fitted in the accommodation space formed together with the positioning mechanism 50 as shown in FIG.

As shown in FIG. 4A, the magnet turntable 20 is magnetized in the inner ring magnetic region 201, the outer ring magnetic region 202, and the upper positioning magnetic region 203, and the outer ring magnetic region 202 is the outer ring processing of the peripheral edge of the magnet turntable 20 main body. The inner ring magnetic region 201 is arranged at the outer ring of the central circular hole 211 of the magnet turntable 20, and the upper positioning magnetic region 203 is relatively located between the inner ring magnetic region 201 and the outer ring magnetic region 202. NS.

The inner ring magnetic region 201 is evenly divided and magnetized at at least four poles arranged according to the NSNS polarity, as shown in FIGS. 4A and 4B, and is actually a multiple of two poles (NS) as needed. For example, the number of poles such as 6 poles, 8 poles, 10 poles, and 12 poles can be selected. The outer ring magnetic region 202 is evenly divided and magnetized with 30 pole pairs (60 poles) arranged according to the NSNS polarity, as shown in FIGS. 4A and 4B, and in practice, two poles (NS) as needed. ) To increase. As shown in FIGS. 4A and 4B, the upper positioning magnetic region 203 is magnetized by three poles arranged according to the NSN polarity, and in practice, the SNS polarity is selected and arranged by different detection devices.

The first IC board 30 is fixed to the first stud 121 penetrating the positioning mechanism 50, is relatively arranged between the magnet turntable 20 and the positioning mechanism 50, and has an inner ring magnetic region 201 of the magnet turntable 20. And used to detect corresponding to the outer ring magnetic region 202.

The first IC board 30 outputs R, S, and T pulse signals by matching the inner ring magnetic region 201 of the magnet turntable 20 and using the magnetic principle to detect the magnet turn. The outer ring magnetic region 202 of the table 20 is combined and the pulse signals of A and B are output using the magnetic principle for detection.

The detection device transmits a signal to the controller by electrical connection via the R, S, T pulse signal and the A, B pulse signal output from the first IC board 30 (not shown), and uses it as a motor drive control. For example, the best control effect can be obtained by detecting the rotation direction and the rotation speed of the rotation shaft 11.

The second IC board 40 is fixed to the second stud 57 with screws 41 and is opposite to the magnet turntable 20 and the positioning mechanism 50 in order to detect corresponding to the upper positioning magnetic region 203 of the magnet turntable 20. Placed in.

The second IC board 40 aligns the upper positioning magnetic region 203 of the magnet turntable 20 and uses the magnetic principle to output the upper positioning pulse signal or the upper positioning pulse signal by electrical connection. Is sent to the controller (not shown) to control the position of the upper positioning needle stop of the sewing machine.

Upon request for work, a set of three poles of the lower positioning magnetic region 204 is provided at a position 180 degrees opposite to the upper positioning magnetic region 203, and as shown in FIG. 4B, like the upper positioning magnetic region 203, the NSN. It is arranged according to the polarity of, or also according to the polarity of SNS, and corresponds to the lower positioning position of the motor.

In order to avoid the phenomenon of magnetic interference during magnetization, the height of the inner ring magnetic region 201, the outer ring magnetic region 202, and the non-magnetic region 205 other than the upper positioning magnetic region 203 or the lower positioning magnetic region 204 shown in FIG. 4A is set. , Lower than the inner ring magnetic region 201, the outer ring magnetic region 202, and the upper positioning magnetic region 203 or the lower positioning magnetic region 204. The height reduction range of the non-magnetic region 205 is 0.2 to 0.6 mm, preferably 0.4 mm.

The second IC board 40 can also loosen the screw 56 originally locked in the adjusting hole 541 as shown in FIG. 6A, and further, as shown in FIG. 6B, according to the requirements of the actual work. The positioning mechanism 50 is directly rotated to adjust the position of the second IC board 40 on the second stud 57, thereby adjusting the relative position of the second IC board 40 and the upper positioning magnetic region 203. It can be adjusted and the top positioning point is fine-tuned to facilitate adjustment by the operator. If desired, the second stud 57 may be placed directly at the appropriate position on the rear lid 12 to align and detect the magnet turntable 20, and the adjustment function may be omitted.

During the adjustment, the diameters and shapes of the first opening 53 and the adjusting hole 541 through which the first stud 121 penetrates in the positioning mechanism 50 are matched with each other, and the positioning mechanism 50 rotates. When the first stud 121 penetrates the first opening 53, the positioning mechanism 50 makes use of the structure with respect to the first stud 121 through the first opening 53. It can rotate and does not affect the rotation of the positioning mechanism 50. Assuming that the rotation of the positioning mechanism 50 is not affected, the installation position of the first stud 121, the fixed structure of the first IC board 30, and the shape of the positioning mechanism 50 body are selectively selected according to the actual situation. Can be changed.

The first IC board 30 of this embodiment can also be used alone with the magnet turntable 20. When the first IC board 30 is used alone, as shown in FIG. 7, the first IC board 30 can be directly locked to the first stud 121 on the rear lid 12, and the magnet turn. The magnetic region corresponding to the table 20 is matched, a pulse signal is output, and another external positioning signal device is added to control the operation of the motor 10.

In the present invention, as shown in FIG. 5, a handwheel 70 can be added as an option, and the handwheel 70 is directly fixed to the rotating shaft 11, so that the handwheel 70 can directly drive the rotating shaft 11 and a magnet. The turntable 20 can synchronously detect the rotational state of the handwheel 70. The motor 10 is covered by adding a heat shield (not shown) for heat insulation.

In the present invention, since the magnet turntable 20 is directly provided on the rotating shaft 11 and rotates in synchronization with the rotating shaft 11, the generated detection signal is obtained from the absolute position, and the signal is not distorted. , All numerical values are acquired directly from the rotating shaft 11 and can generate more accurate and distortion-free signals, more absolute monitoring and controlling numerical values compared to the general indirect acquisition method, and moreover of the sewing machine motor. The optimum control effect for operation can be obtained.

Since the present invention controls the drive and positioning of the motor by magnetic detection, the operation of the sewing machine motor has a control effect without fear of contamination of oil and gas or moisture, and coating of lint dust.

As described above, the present invention is not limited to the above-described embodiment, and can be implemented in various embodiments without departing from the spirit of the invention.

10 Motor 11 Rotating shaft 111 Ring groove 12 Rear lid 121 First stud 20 Magnet turntable 201 Inner ring magnetic area 202 Outer ring magnetic area 203 Upper positioning magnetic area 204 Lower positioning magnetic area 205 Non-magnetic area 21 Flange 211 Center circular hole 22 Gap Adjuster 23 C-shaped buckle 30 First IC board 31 Screw 40 Second IC board 41 Screw 50 Positioning mechanism 51 Boss 54 Rug 541 Adjusting hole 55 Concave groove 56 Screw 57 Second stud 52 Center hole 60 Turntable lid 70 Handwheel

Claims (22)

It is a rotation axis detection device for sewing machine motors.
Used for mounting the motor, a rotating shaft is provided on the front lid of the motor.
The rotation axis detection device includes a magnet turntable and a first IC board.
The magnet turntable is inserted into an annular groove fixed to the rotation shaft with a circular hole in the center and rotates in synchronization with the rotation shaft, so that the magnet turntable is magnetized in the inner ring magnetic region and the outer ring magnetic region. ,
The first IC board detects the inner ring magnetic region and the outer ring magnetic region, outputs R, S, and T pulse signals, respectively, and is fixed to the rear lid in order to output A and B pulse signals. Has been
Since the magnet turntable is directly fixed to the rotating shaft and rotates in synchronization with the rotating shaft, the absolute position of the rotating shaft can be detected and the generated signal is not distorted. Rotation axis detection device for sewing motors. The rotation axis detection device includes a second IC board provided on the rear lid, and the magnet turntable is said to output a corresponding detection and upper positioning pulse signal by the second IC board. Claim 1 is characterized in that an upper positioning magnetic region is provided between the inner ring magnetic region and the outer ring magnetic region, and the operation of the motor is controlled in combination with a pulse signal output from the first IC board. The rotary axis detection device of the sewing machine motor described in 1. The rotation axis detection device is provided with a positioning mechanism on the rear lid, the positioning mechanism is provided with a second IC board, and the magnet turntable is a corresponding detection by the second IC board and an upper positioning pulse signal. An upper positioning magnetic region is provided between the inner ring magnetic region and the outer ring magnetic region, and the operation of the motor is controlled in combination with the pulse signal output from the first IC board. The rotary axis detection device for a sewing machine motor according to claim 1. The rear lid is provided with at least one first stud for fixing the first IC board, and the positioning mechanism corresponds to the first stud for the first stud to pass through. The rotation axis detection device for a sewing machine motor according to claim 3, wherein the first opening is provided. A plurality of lugs are provided on the peripheral edge of the positioning mechanism, and an adjusting hole for locking is provided at each of the lugs. When the lugs are loosened, the positioning mechanism is rotated to rotate the second IC board and the upper portion. The rotation axis detection device for a sewing machine motor according to claim 4, wherein the position relative to the positioning magnetic region can be adjusted and the sewing machine motor rotates relative to the first stud through the first opening. A plurality of lugs are provided on the peripheral edge of the positioning mechanism, and an adjusting hole for locking is provided at each of the lugs. When the lugs are loosened, the positioning mechanism is rotated to rotate the second IC board and the upper portion. The rotation axis detection device for a sewing machine motor according to claim 3, wherein the position relative to the positioning magnetic region can be adjusted. 5. The rotation axis detection device of the sewing machine motor described in 1. The rotation axis detection device includes a turntable lid, and the turntable lid is sleeved inside a ring groove of the rotation shaft to cover the outside of the magnet turntable and the first IC board. The rotation axis detection device for a sewing machine motor according to claim 1, wherein the rotation axis detection device is fixed to a rear lid. The rotation axis detection device includes a turntable lid, and the turntable lid covers the outside of the magnet turntable, the first IC board, and the second IC board and is fixed to the rear lid. The rotary axis detection device for a sewing machine motor according to claim 2 or 3. The rotation of the sewing machine motor according to claim 1, wherein the inner ring magnetic region of the magnet turntable is magnetized at at least four poles according to a polar arrangement in order to be detected by the first IC board. Axis detector. The sewing machine motor according to claim 1, wherein the outer ring magnetic region of the magnet turntable is magnetized with twice the number of poles according to the polar arrangement because it is detected by the first IC board. Rotating axis detector. The rotation axis detection device for a sewing machine motor according to claim 11, wherein the number of poles in the outer ring magnetic region is 60 poles. A claim characterized in that the upper positioning magnetic region of the magnet turntable is magnetized at three poles according to an arrangement of either NSN polarity or SNS polarity in order to be detected by the first IC board. 2. The rotary axis detection device for a sewing machine motor according to 2. The magnet turntable is provided with a lower positioning magnetic region at a position 180 degrees opposite to the upper positioning magnetic region, and the second IC board detects the lower positioning magnetic region accordingly and lower positioning. The rotation axis detection device for a sewing machine motor according to claim 2, wherein a pulse signal is output to control the stop position of the lower positioning needle of the sewing machine. The rotation of the sewing machine motor according to claim 14, wherein the magnet turntable has a region without magnetic poles, and the height of the region without magnetic poles is smaller than the height of the lower positioning magnetic region. Axis detector. The rotation axis detection device for a sewing machine motor according to claim 15, wherein the height of the region without magnetic poles is reduced to 0.2 to 0.6 mm. The rotation axis detection device for a sewing machine motor according to claim 16, wherein the height in which the region without magnetic poles is reduced is 0.4 mm. The magnet turntable has a region without magnetic poles, and the height of the region without magnetic poles is smaller than the height of the inner ring magnetic region, the outer ring magnetic region, and the upper positioning magnetic region. The rotation axis detection device for a sewing machine motor according to claim 2 or 3. The rotation axis detection device for a sewing machine motor according to claim 18, wherein the height of the region without magnetic poles is reduced to 0.2 to 0.6 mm. The rotation axis detection device for a sewing machine motor according to claim 19, wherein the height in which the region without magnetic poles is reduced is 0.4 mm. The rotary axis detection device for a sewing machine motor according to claim 1, 2 or 3, wherein the material of the magnet turntable is a plastic material and an iron oxide magnet. The rotation axis detection device for a sewing machine motor according to claim 1, wherein the rotation axis detection device further includes a hand wheel fixed to the rotation axis.

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