Method and apparatus for automatically decelerating and stopping a sewing machine motor

Claim 3

The method of claim 1 and further comprising the step of allowing the motor to run at needle positioning speed for a time interval after reaching needle positioning speed.

Claim 4

The method of claim 1 wherein the step of adjusting comprises comparing the motor angle when needle positioning speed is reached to the needle positioning angle and adjusting the predetermined braking angle for successive sewing cycles such that the time for braking to needle positioning speed is equal to the time required for the motor to rotate to sew the desired number of stitches to complete the seam and to reach the needle positioning angle.

Claim 5

The method of claim 1 wherein the step of decelerating the motor to stop reciprocation occurs within a predetermined angle difference between the motor angle and the needle positioning angle.

Claim 8

The method of claim 5 wherein the step of applying the brake to reduce the speed to needle positioning speed comprises: comparing the sensed motor angle to the preset braking angle; applying the brake when the sensed motor angle essentially equals the preset braking angle; and releasing the brake when the speed is reduced to needle positioning speed.

Claim 9

The method of claim 5 wherein the predetermined error is 10°.

Claim 10

The method of claim 5 wherein the steps of comparing the motor angle and stopping reciprocation comprise: comparing the motor angle when needle positioning speed is reached with the needle positioning angle; adjusting the braking angle by the difference when the difference is greater than a predetermined angle; allowing the motor to rotate at needle positioning speed until the difference between the motor angle and the needle positioning angle is less than the predetermined angle; and applying the brake to stop the motor when the difference between the motor angle and the needle positioning angle is less than the predetermined angle.

Claim 11

The method of claim 8 wherein the step of allowing the motor to rotate comprises allowing the motor to rotate in predetermined angular increments less then 360°.

Claim 14

Apparatus for automatically decelerating a sewing machine motor and positioning a reciprocating needle on the sewing machine comprising: means for sensing the motor angle; means for decelerating the motor when the motor angle equals a predetermined braking angle to sew the desired number of stitches to complete the seam while reducing the speed to a needle positioning speed; means for sensing the motor angle after the speed has been reduced at or below said needle positioning speed and comparing the motor angle with a desired needle positioning angle; means for decelerating the motor to stop reciprocation of the needle when the motor angle equals or is greater than the needle positioning angle such that needle reciprocation is stopped at the desired position in a minimum time duration without performing an additional stitch and; means for adjusting the predetermined braking angle as a function of previous braking operations to minimize the time duration between deceleration to needle positioning speed and when the motor angle equals or is greater than the needle positioning angle.

Claim 15

Apparatus for automatically decelerating a sewing machine motor and positioning a reciprocating needle on the sewing machine comprising: means for sensing the motor angle; means for decelerating the motor when the motor angle equals a predetermined braking angle to sew the desired number of stitches to complete the seam while reducing the speed to a needle positioning speed; means for sensing the motor angle after the speed has been reduced at or below said needle positioning speed and comparing the motor angle with a desired needle positioning angle; means for decelerating the motor to stop reciprocation of the needle when the motor angle equals or is greater than the needle positioning angle such that needle reciprocation is stopped at the desired position in a minimum time duration without performing an additional stitch and; means for adjusting the predetermined braking angle as a function of previous braking operations to minimize the time duration between deceleration to needle positioning speed and when the motor angle equals or is greater than the needle positioning angle.

Claim 16

Apparatus for automatically decelerating a sewing machine motor and positioning a reciprocating needle on a sewing machine comprising: means for sensing the motor angle and the rotational speed of said motor; means for decelerating said motor; a microprocessor controller coupled to said sewing machine for controlling said means for decelerating and responsive to said means for sensing; said microprocessor controller being operable in one mode for decelerating said motor when the motor angle equals a preset braking angle to reduce the speed of said motor to a needle positioning speed; said microprocessor controller in a second mode at or below the needle positioning speed being operable to compare the motor angle with a desired needle positioning angle and decelerating said motor to stop reciprocation of said needle when said motor angle equals or is greater than the needle positioning angle, such that needle reciprocation is stopped for a minimum rotation of said motor without performing an additional stitch and; said microprocessor controller in a third mode for comparing the motor angle to the needle positioning angle when said motor reaches said needle positioning speed and for adjusting said preset braking angle by the difference therebetween.

Claim 17

Apparatus for automatically decelerating a sewing machine motor and positioning a reciprocating needle on a sewing machine comprising: means for sensing the motor angle and the rotational speed of said motor; means for decelerating said motor; a microprocessor controller coupled to said sewing machine for controlling said means for decelerating and responsive to said means for sensing; said microprocessor controller being operable in one mode for decelerating said motor when the motor angle equals a preset braking angle to reduce the speed of said motor to a needle positioning speed; said microprocessor controller in a second mode at or below the needle positioning speed being operable to compare the motor angle with a desired needle positioning angle and decelerating said motor to stop reciprocation of said needle when said motor angle equals or is greater than the needle positioning angle, such that needle reciprocation is stopped for a minimum rotation of said motor without performing an additional stitch and; said microprocessor controller in a third mode for comparing the motor angle to the needle positioning angle when said motor reaches said needle positioning speed and for adjusting said preset braking angle by the difference therebetween.

Claim 18

The apparatus of claim 12 wherein said means for sensing comprises: a first sensor for sensing incremental advances of said motor rotation; and a second sensor for sensing a complete revolution of said motor.

Claim 19

The apparatus of claim 12 wherein said means for decelerating comprises an electromagnetic brake attached to said motor.

Claim 20

The apparatus of claim 12 wherein said microprocessor controller in said second mode decelerates said motor to stop reciprocation when said motor angle is within a predetermined number of degrees of said needle positioning angle or said motor angle is greater than said needle positioning angle.

Claim 21

A semi-automatic sewing system, comprising: a sewing machine; said sewing machine including a reciprocating needle for stitching a seam in material advanced along a feed direction, and controls for operating said sewing machine; means for driving said sewing machine, said driving means including a variable speed motor with a shaft; means for braking said motor; means for sensing rotation and angular displacement of said motor shaft; a microprocessor controller operatively associated with said braking means, said sensing means and said sewing machine controls; said microprocessor controller having plural operational modes and being responsive to said means for sensing and said braking means; said microprocessor controller being operable in one mode to compare said motor angle with a braking angle to decelerate said motor to a needle positioning speed when said motor angle essentially equals said braking angle; said microprocessor controller in another mode being operable to compare the motor angle to a needle positioning angle and to decelerate said motor when said motor angle is equal to or greater than said needle positioning angle such that needle reciprocation is terminated for a minimum rotation of said motor without performing an additional stitch and; said microprocessor controller in an additional mode for comparing the motor angle to the needle positioning angle when said motor reaches said needle positioning speed and for adjusting said preset braking angle by the difference therebetween.

Claim 22

A semi-automatic sewing system, comprising: a sewing machine; said sewing machine including a reciprocating needle for stitching a seam in material advanced along a feed direction, and controls for operating said sewing machine; means for driving said sewing machine, said driving means including a variable speed motor with a shaft; means for braking said motor; means for sensing rotation and angular displacement of said motor shaft; a microprocessor controller operatively associated with said braking means, said sensing means and said sewing machine controls; said microprocessor controller having plural operational modes and being responsive to said means for sensing and said braking means; said microprocessor controller being operable in one mode to compare said motor angle with a braking angle to decelerate said motor to a needle positioning speed when said motor angle essentially equals said braking angle; said microprocessor controller in another mode being operable to compare the motor angle to a needle positioning angle and to decelerate said motor when said motor angle is equal to or greater than said needle positioning angle such that needle reciprocation is terminated for a minimum rotation of said motor without performing an additional stitch and; said microprocessor controller in an additional mode for comparing the motor angle to the needle positioning angle when said motor reaches said needle positioning speed and for adjusting said preset braking angle by the difference therebetween.

Claim 23

The apparatus of claim 16 wherein said means for sensing comprises: a rotating disk attached to the shaft of said motor having a plurality of incremental indicators disposed circumferentially thereabout; a first sensor for sensing each increment on said disk; and a second sensor for sensing a complete revolution of said disk to provide a sync signal to said microprocessor controller.

Claim 24

The apparatus of claim 16 wherein said means for decelerating comprises an electromagnetic brake.

Claim 25

The apparatus of claim 16 wherein said microprocessor controller in said additional mode adjusts said braking angle only when the difference between the motor angle and said needle positioning angle is greater than 10°.

Claim 26

The apparatus of claim 16 wherein said microprocessor controller is operable in said one mode to compare said motor angle with said preset braking angle after an indication has been received from said sewing controls to stop reciprocation and begin decelerating said motor when said motor angle equals or has exceed said braking angle.