Bobbin monitor for sewing machines

Claim 2

A monitor for indicating depletion of the bobbin thread of a sewing machine driven by an electric motor having an operating circuit including a treadle switch controlled by the machine operator and a source of electric power, said monitor comprising: a. an electrically actuated signal device having an operating circuit including said signal device, said power source, and a normally open signal switch, but not said treadle switch, b. a counter operable at and after a pre-determined reading thereof to actuate said signal device by closing said signal switch, c. manually actuated reset means operable to reset said counter to a reading representing a full bobbin, whereby once actuated, said signal device remains actuated even when said treadle switch is opened, and until said counter is reset, and d. driving means interconnecting said counter to a powered element of said sewing machine and operable to advance said counter at a rate proportional to the length of the stitch line being sewed, the reset and signal readings of said counter being so related that said signal device will be actuated when a pre-determined proportion of the bobbin thread has been exhausted.

Claim 3

A monitor for indicating depletioN of the bobbin thread of a sewing machine comprising: a. a signal device, b. a counter operable at and after a pre-determined reading thereof to actuate said signal device, c. manually actuated reset means operable to reset said counter to a reading representing a full bobbin, d. driving means interconnecting said counter to a powered element of the sewing machine and operable to advance said counter at a rate proportional to the length of the stitch line being sewed, the reset and signal readings of said counter being so related that said signal device will be actuated when a pre-determined proportion of the bobbin thread has been exhausted, e. disabling means operable by actuation of said signal device to disable the sewing machine to prevent further operation thereof until said counter is reset, and f. override means operable to render said disabling means effective only when the sewing machine is stopped, whereby a stitch line being sewed at the time the signal is actuated may be completed before the machine is disabled.

Claim 4

A monitor for indicating depletioN of the bobbin thread of a sewing machine comprising: a. a signal device, b. a counter operable at and after a pre-determined reading thereof to actuate said signal device, c. manually actuated reset means operable to reset said counter to a reading representing a full bobbin, d. driving means interconnecting said counter to a powered element of the sewing machine and operable to advance said counter at a rate proportional to the length of the stitch line being sewed, the reset and signal readings of said counter being so related that said signal device will be actuated when a pre-determined proportion of the bobbin thread has been exhausted, e. disabling means operable by actuation of said signal device to disable the sewing machine to prevent further operation thereof until said counter is reset, and f. override means operable to render said disabling means effective only when the sewing machine is stopped, whereby a stitch line being sewed at the time the signal is actuated may be completed before the machine is disabled.

Claim 5

A monitor as recited in claim 2 with the addition of manually operable means operable to render said disabling means inoperable even when said machine is stopped, whereby the machine may be restarted, said manually operable means requiring manual positioning by the operator at the time the machine is restarted.

Claim 6

A monitor as recited in claim 2 wherein said sewing machine is driven by an electric motor having an operating motor circuit including an operator-controlled treadle switch and a source of electric power, wherein said signal device is electrically actuated and has an operating signal circuit including said source of electric power, said signal device, and a normally open signal switch operable to be closed by said counter at and after a predetermined reading thereof, but not said treadle switch, wherein said disabling means constitutes a normally closed relay included in said motor circuit but operable to be opened by energization of the coil thereof, and a disabling circuit including said power source, said signal switch and said relay coil, but not said treadle switch, and wherein said override means comprises: a. a normally closed override switch disposed in said disabling circuit, b. operating means for said override switch, and c. means connecting said switch operating means to a powered element of said sewing machine and operable to maintain said override switch open as long as said machine is operating, but to close said switch when the machine is stopped.

Claim 7

A monitor as recited in claim 4 with the addition of a normally closed, manually operable pushbutton switch interposed in said disabling circuit, whereby by pressing said pushbutton, the machine may be restarted even though said signal switch and said override switch are closed.

Claim 8

A monitor as recited in claim 5 with the addition of: a. means rendering the manually operable reset element of said counter inaccessible to the machine operator, b. electrically actuated reset means operable when energized to actuate said reset element to reset said counter, c. a normally open reset switch inaccessible to the operator except when the work being sewed is removed from the machine, and d. an operating electric circuit including a source of electric power, said reset means, and said reset switch.