Sewing Machine Drive

Abstract

A magnetic encoder system of a sewing machine drive comprises a magnetic, magnetised disc with alternating north and south pole elements, which are used as incremental markings. The latter are designed as a full ring-incremental track, which extends around a circumference of the ferritic disc, and as an annular section incremental track, which is designed as an annular section on the ferritic disc. The result is a magnetic encoder system for a servomotor of a sewing machine.

Claims

1. A sewing machine drive with a magnetic encoder system comprising: a disc made from magnetic material, wherein the disk is magnetised with alternating north and south pole elements, wherein the alternating north and south pole elements define incremental markings, a full ring incremental track, having incremental markings comprised of alternating north and south pole elements and arranged as a ring over 360 along a circumference of the disc and an additional annular section incremental track, having incremental markings comprised of alternating north and south pole elements and arranged as an annular section on the disc.

2. The sewing machine drive according to claim 1 wherein the full ring incremental track is used for determining the position and speed information.

3. The sewing machine drive according to claim 1, wherein the annular section incremental track is used for zero point referencing.

4. The sewing machine drive according to claim 1, further comprising an evaluation unit with integrated microcontroller and magnet sensors performs the evaluation of the full ring incremental track.

5. The sewing machine drive according to claim 1, wherein a further, separate magnet sensor is used to detect the annular section incremental track.

6. The sewing machine drive according to claim 1 wherein one of the full ring incremental track and annular section incremental track is disposed radially outwardly of the other one of the full ring incremental track and annular section incremental track.

7. The sewing machine drive according to claim 6, further comprising an evaluation unit comprised of a plurality of magnet sensors with one of the magnet sensors detecting the full ring incremental track and another one of the magnet sensors detecting the annular section incremental track.

8. The sewing machine drive according to claim 7, wherein the evaluation unit is equipped with a microcontroller.

9. The sewing machine drive according to claim 7, further comprising a rotary sewing machine drive shaft generally coaxial with one of the full ring incremental track and annular section incremental track.

10. The sewing machine drive according to claim 1, further comprising a rotary sewing machine drive shaft about which the full ring incremental track generally coaxially extends.

11. The sewing machine drive according to claim 10, wherein the annular section incremental track is disposed radially inwardly of the full ring incremental track between the full ring incremental track and the sewing machine drive shaft.

12. The sewing machine drive according to claim 11, further comprising an evaluation unit comprised of a plurality of magnet sensors with one of the magnet sensors detecting the full ring incremental track and another one of the magnet sensors detecting the annular section incremental track.

13. The sewing machine drive according to claim 1, further comprising: (a) a servomotor driven rotary sewing machine drive shaft about which (i) the full ring incremental track generally coaxially extends, and (ii) the annular section incremental track generally annularly extends, and (b) a processor-equipped evaluation unit comprised of a plurality of magnet sensors with one of the magnet sensors detecting alternating north and south poles of the full ring incremental track and another one of the magnet sensors detecting alternating north and south poles of the annular section incremental track.

14. The sewing machine drive according to claim 1, further comprising: (a) a servomotor driven rotary sewing machine drive shaft about which (i) the full ring incremental track generally coaxially extends, and (ii) the annular section incremental track generally annularly extends, and (b) an evaluation unit configured to detect (i) north and south pole elements of the full ring incremental track, and (ii) north and south pole elements of the annular section incremental track.

15. The sewing machine drive according to claim 14, wherein the disc is carried by the sewing machine drive shaft for rotation of the disc, the full ring incremental track, and the annular section incremental track substantially in unison therewith; and wherein the evaluation unit is mounted stationary relative to the sewing machine drive shaft, the full ring incremental track, and the annular section incremental track.

16. The sewing machine drive according to claim 15, wherein the evaluation unit is configured to detect (i) north and south pole elements of the full ring incremental track for determining position and speed information thereof, and (ii) detecting north and south pole elements of the annular section incremental track for determining a zero point reference therefor.

17. The sewing machine drive according to claim 16, wherein the evaluation unit comprised of a plurality of magnet sensors with one of the magnet sensors detecting north and south pole elements of the full ring incremental track for determining position and speed information thereof, and another one of the magnet sensors detecting north and south pole elements of the annular section incremental track for determining a zero point reference position therefor.

18. A sewing machine drive with a magnetic encoder system comprising: (a) a servomotor-driven rotary sewing machine drive shaft; (b) a disc comprising a full ring incremental track comprised of alternating north and south pole elements defining one set of incremental markings, and an annular section incremental track comprised for alternating north and south pole elements defining another set of incremental markings; and (c) an evaluation unit configured to detect north and south pole elements of the full ring incremental track and north and south pole elements of the annular section incremental track during rotation of the sewing machine drive shaft.

19. The sewing machine drive according to claim 18, wherein the disc is carried by the sewing machine drive shaft for rotation of the disc, the full ring incremental track, and the annular section incremental track substantially in unison with the sewing machine drive shaft; and wherein the evaluation unit is mounted stationary relative to the sewing machine drive shaft, the full ring incremental track, and the annular section incremental track.

20. The sewing machine drive according to claim 19, wherein the evaluation unit is comprised of a plurality of magnet sensors with one of the magnet sensors detecting north and south pole elements of the full ring incremental track for determining position and speed information thereof, and another one of the magnet sensors detecting north and south pole elements of the annular section incremental track for determining a zero point reference position therefor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 shows a perspective view of an encoder system assembly for attachment onto a servomotor of a sewing machine;

[0019] FIG. 2 shows a perspective plan view of the encoder system assembly;

[0020] FIG. 3 shows a perspective detailed view of a magnetic encoder system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of a magnetic encoder system for a sewing machine drive in the form of a servomotor of a sewing machine is explained in the following with reference to FIGS. 1, 2 and 3.

[0022] An encoder system assembly 1 is used for securing a magnetic encoder system 2 to a servomotor for a sewing machine. The assembly 1 contains an attachment flange 3 next to the magnetic encoder system 2. By means of the attachment flange 3 the magnetic encoder system 2 is secured onto the servomotor. A motor shaft 4 of the otherwise not shown servomotor is guided through an opening in the attachment flange 3 and through the circular, central passage opening of the magnetic encoder system 2

[0023] A magnetic, in particular ferritic disc 5 of the magnetic encoder system 2 annularly surrounding the through opening is connected in a rotationally secure manner to the motor shaft 4 of the servomotor. On a plate 6 mounted additionally on the attachment flange 3 there is an evaluation unit 7. The latter is designed to be stationary relative to the attachment flange 3 (cf. FIG. 2).

[0024] The magnetic encoder system 2 comprises in addition to the evaluation unit 7 a full ring incremental track 8 and an annular section incremental track 9 (cf. FIG. 3). The full ring-incremental track 8 and the annular section incremental track 9 extend around a circumference of a magnetic disc 5, wherein the annular section incremental track 9 only comprises a portion of the circumference. Incremental tracks 8, 9 have alternating north pole elements 10 and south pole elements 11. The incremental tracks 8 and 9 are arranged coaxially relative to one another and to the motor shaft 4, wherein a radius R.sub.A of the annular section incremental track 9 is smaller than a radius R.sub.V of the full ring incremental track 8 (cf. FIG. 3).

[0025] The evaluation unit 7 is arranged opposite the magnetic disc 5 so that a first, not shown magnet sensor of the evaluation unit 7 detects the full ring-incremental track 8 and a further magnet sensor of the evaluation unit 7 not shown in detail detects the annular section incremental track 9. The two magnet sensors are arranged offset radially to one another.

[0026] Different, not shown additional variants of the encoder system assembly are possible.

[0027] Instead of exactly one annular section incremental track according to the annular section incremental track 9 of the embodiment described above, also more annular section incremental tracks can be provided. Circumferential extensions of the annular sections of said annular section incremental tracks can differ from one another. If in such a case for example two or three annular section incremental tracks with different circumferential extensions are provided, it is possible in principle to achieve a rotary direction detection with such a variant of the encoder system. In such a case two different types of circumferential extensions are sufficient. For example, a sequence of short/long/long can be distinguished from a sequence long/long/short for recognising the direction of rotation.

[0028] If a plurality of full ring incremental tracks are used, the latter can be arranged on different radius sections relative to the common axis of rotation. This facilitates a magnet sensor scanning of said incremental tracks.