Bobbin runout signalling device

Claim 2

The combination with a bobbin case containing a supply of bobbin thread and a control for sensing runout of said bobbin thread and an empty bobbin case in a sewing machine of a sensor assembly providing a signal to said control in response to runout of said bobbin thread, said control including a sewing machine motor, said sensor assembly including a support, a resilient sensor blade, mEans including electrical insulation mounting said sensor blade on said support for pivotal movement between an operative and sensing position wherein said sensor blade is arranged to resiliently bear against said bobbin thread as it emerges from said bobbin case and an inoperative and clearance position wherein said sensor blade is removed from said bobbin case such that an empty bobbin case may be replaced by a loaded bobbin case, and means responsive to said signal from said sensor assembly for deenergizing said motor.

Claim 3

The combination according to claim 1 wherein said support is in the form of a sewing machine slide plate.

Claim 4

The combination according to claim 1 wherein the mounting means includes a pivot and a spring mounting said sensor blade for pivotal movement, said spring normally biasing said sensor blade into said operative and sensing position.

Claim 5

The combination according to claim 1 wherein the mounting means includes a sewing machine slide plate serving as said support and said insulation includes an insulating board mounted on the underside of said slide plate, a pivot on said board mounting said sensor blade for pivotal movement and a spring operatively connected to and biasing said sensor blade into said operative and sensing position.

Claim 6

In a sewing machine including a support, stitching mechanisms having a needle adapted to receive a needle thread, a bobbin mechanism adapted to receive successive electrically conductive bobbin cases each containing a supply of bobbin thread and a machine control including a drive motor for activating said stitching mechanisms to form successive stitches from said needle and bobbin threads, the improvement comprising a bobbin thread monitor including a flexible and electrically conductive sensor blade, means for mounting said sensor blade in an operative position relative to said bobbin mechanism wherein a contact portion of said sensor blade is adapted to resiliently bear against the bobbin thread emerging from a bobbin case in said bobbin mechanism and is electrically isolated from said bobbin case by the intervening bobbin thread, said bobbin case including thread guiding and tensioning means for said bobbin thread as it emerges from said bobbin case, both said thread guiding and tensioning means and said contact portion of sensor blade being substantially diametrically opposed to said needle whereby runout sensing is accomplished with a tail of bobbin thread extending from said needle, and means in said machine control responsive to said sensor blade making electrical contact with said bobbin case when the bobbin therein runs out for deactivating said stitching mechanisms.

Claim 7

In a sewing machine including a support, stitching mechanisms having a needle adapted to receive a needle thread, a bobbin mechanism adapted to receive successive electrically conductive bobbin cases each containing a supply of bobbin thread and a machine control including a drive motor for activating said stitching mechanisms to form successive stitches from said needle and bobbin threads, the improvement comprising a bobbin thread monitor including a flexible and electrically conductive sensor blade, means for mounting said sensor blade in an operative position relative to said bobbin mechanism wherein a contact portion of said sensor blade is adapted to resiliently bear against the bobbin thread emerging from a bobbin case in said bobbin mechanism and is electrically isolated from said bobbin case by the intervening bobbin thread, said bobbin case including thread guiding and tensioning means for said bobbin thread as it emerges from said bobbin case, both said thread guiding and tensioning means and said contact portion of sensor blade being substantially diametrically opposed to said needle whereby runout sensing is accomplished with a tail of bobbin thread extending from said needle, and means in said machine control responsive to said sensor blade making electrical contact with said bobbin case when the bobbin therein runs out for deactivating said stitching mechanisms.

Claim 8

In a sewing machine according to claim 5, means mounting said sensor blade for movement to an inoperative and clearance position relative to said bobbin mechanism whereby an empty bobbin case may be removed therefrom and replaced by a full bobbin case, said sensor blade being movably mounted such that a machine operator, upon reaching for said empty bobbin case with one hand, displaces said sensor blade into said clearance position whereupon said empty bobbin case may be removed from said bobbin mechanism with that one hand.

Claim 9

In a sewing machine according to claim 6, said mounting means including a pivot for said sensor blade and a spring normally biasing said sensor blade into said operative position.