Arrangement for detecting the position of the sewing needle in a sewing machine

Claim 2

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said fluxresponsive means comprises Hall generator means including a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes; and further including current source means connected across said control electrodes for establishing flow of a control current through said Hall generator semiconductor element; and a detecting circuit comprising a pair of transistors and means so connecting the electrodes of said transistors to the electrodes of said Hall generator semiconductor element that when magnetic flux of one polarity passes through said semiconductor element one of said transistors becomes conductive whereas when magnetic flux of opposite polarity passes through said semiconductor element the other of said transistors becomes conductive.

Claim 3

In a sewing machine as defined in claim 1, wherein said current source means comprises a constant-current source.

Claim 4

In a sewing machine as defined in claim 1, wherein said magnet means comprises a permanent magnet extending in direction circumferentially with respect to the axis of rotation of said rotary member a distance several times greater than the circumferential extent of said Hall semiconductor element with respect to said axis.

Claim 5

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means including a Hall semiconductor element and magnetic yoke means positioned adjacent said Hall semiconductor element, said magnetic yoke means extending in direction circumferentially of the axis of rotation of said rotary member and serving to form a magnetic circuit with said magnet means when said magnet means rotates into the vicinity of said yoke means, said yoke means being so configured and oriented with respect to said Hall semiconductor element as to effect passage through the latter of the flux originating from said magnet means when the angular orientation of said rotary member lies within a predetermined range corresponding to the circumferential extension of said yoke means, to induce in said Hall semiconductor element a Hall voltage indicating when the angular rotation of said rotary member lies within said predetermined range.

Claim 6

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means including a Hall semiconductor element and magnetic yoke means positioned adjacent said Hall semiconductor element, said magnetic yoke means extending in direction circumferentially of the axis of rotation of said rotary member and serving to form a magnetic circuit with said magnet means when said magnet means rotates into the vicinity of said yoke means, said yoke means being so configured and oriented with respect to said Hall semiconductor element as to effect passage through the latter of the flux originating from said magnet means when the angular orientation of said rotary member lies within a predetermined range corresponding to the circumferential extension of said yoke means, to induce in said Hall semiconductor element a Hall voltage indicating when the angular rotation of said rotary member lies within said predetermined range.

Claim 7

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means; and mounting means mounting said flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means, and wherein said magnet means comprises two permanent magnets each mounted on said rotary member for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of said rotary member, the polarization of said two permanent magnets differing in such a manner that when one of the magnets passes by said Hall generator means a first Hall voltage is generated whereas when the other of the magnets passes by said Hall generator means a second Hall voltage distinguishable from said first Hall voltage is generated.

Claim 8

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on one end of said main shaft, and a drive arrangement for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therewith; flux-responsive means; and mounting means mounting said flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises Hall generator means, and wherein said magnet means comprises two permanent magnets each mounted on said rotary member for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of said rotary member, the polarization of said two permanent magnets differing in such a manner that when one of the magnets passes by said Hall generator means a first Hall voltage is generated whereas when the other of the magnets passes by said Hall generator means a second Hall voltage distinguishable from said first Hall voltage is generated.

Claim 9

In a sewing machine as defined in claim 5, wherein said magnet means comprises two permanent magnets each mounted on said rotary member for rotation therewith but spaced from each other in direction circumferentially of the axis of rotation of said rotary member, and wherein said Hall generator means comprises two Hall generator units spaced from each other in direction circumferentially of the axis of rotation of said rotary member.

Claim 10

In a sewing machine as defined in claim 6, wherein each of said two magnets extends in direction circumferentially with respect to said axis a distance greater than the distance through which each of said Hall generator units extends in circumferential direction.

Claim 11

In a sewing machine as defined in claim 6, wherein each of said two magnets extends in direction circumferentially with respect to said axis a distance less than the distance through which said Hall generator units extend in circumferential direction.

Claim 12

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on oNe end of said main shaft, and a drive arrangemment for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therwith; flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes; and further including means connected across said control electrodes for establishing a flow of control current through said Hall generator semiconductor element; and circuit means including a first electronic switch element having a control input connected between one of said Hall-voltage electrodes and one of said control electrodes of said Hall generator semiconductor element, and a second electronic switch element having a control input connected between the other of said Hall-voltage electrodes and said one of said control electrodes of said Hall generator semiconductor element, and wherein said magnet means comprises two permanent magnets mounted inside said hollow drive pulley member and angularly offset from each other and having respective orientations such that when one of said magnets passes said Hall generator semiconductor element magnetic flux of one polarity penetrates the latter, whereas when the other of said magnets passes said Hall generator semiconductor element magnetic flux of opposite polarity penetrates the latter.

Claim 13

In a sewing machine of the type comprised of a sewing needle, a main rotating shaft, means interconnecting said needle and said shaft for converting rotational movement of said shaft into longitudinal reciprocating movement of said needle, a hollow drive pulley fixedly mounted on oNe end of said main shaft, and a drive arrangemment for driving said main shaft including a drive belt trained around said hollow drive pulley, an arrangement comprising magnet means mounted inside said hollow drive pulley for rotation therwith; flux-responsive means; and mounting means mounting said flux-responsive means on a stationary part of the sewing machine with such an orientation relative to the path of motion of said magnet means that when said drive pulley assumes a predetermined angular orientation corresponding to a predetermined position of said needle a flux-responsive voltage is induced in said flux-responsive means, wherein said flux-responsive means comprises a Hall generator semiconductor element having a pair of control electrodes and a pair of Hall-voltage electrodes; and further including means connected across said control electrodes for establishing a flow of control current through said Hall generator semiconductor element; and circuit means including a first electronic switch element having a control input connected between one of said Hall-voltage electrodes and one of said control electrodes of said Hall generator semiconductor element, and a second electronic switch element having a control input connected between the other of said Hall-voltage electrodes and said one of said control electrodes of said Hall generator semiconductor element, and wherein said magnet means comprises two permanent magnets mounted inside said hollow drive pulley member and angularly offset from each other and having respective orientations such that when one of said magnets passes said Hall generator semiconductor element magnetic flux of one polarity penetrates the latter, whereas when the other of said magnets passes said Hall generator semiconductor element magnetic flux of opposite polarity penetrates the latter.