Sewing – Elements – Starting or stopping
Patent
1982-12-20
1986-01-14
Nerbun, Peter
Sewing
Elements
Starting or stopping
D05B 6926
Patent
active
045639647
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a driving control device for a domestic, electronic sewing machine.
In modern sewing machines with data circuits, arrangements are provided in the electronic system in order to stop the machine when the needle comes to its upper end position. Due to this arrangement to stop the machine in a predetermined needle position, the work piece can be taken out of the machine or positioned in the same without any further adjustment on the machine. A similar advantage can be achieved by a completion of the arrangement with an alternative stop position of the needle at the lower end position thereof. The needle can then be used as a pivot when the operator wants to swing the cloth around the needle through a certain angle. An arrangement such as this will also offer an advantage in a so-called single stitch operation, darning and tacking, as the operator then has time to watch every stitch and to plan for the next one.
The present invention provides a solution to the problem of positioning the needle in a desired position (up or down) by means of the current regulator of the machine. In accordance with the invention a needle stop automatic system of the machine is provided by which not only the stopping of the needle in predetermined positions is achieved when the current from the regulator is switched off but also the positioning thereof in desired end positions (up or down) by the use of short pulses from the regulator. Since the regulator is actuated by a foot in conventional manner, the operator has both her hands free for handling the work piece.
An example of an embodiment of a driving control device according to the invention will now be described with reference to the attached drawing which shows a wiring diagram of the device.
In an electronic sewing machine with a computer 10, the driving motor 11 of the machine is controlled by a control circuit comprising a transistor 12 with a base electrode 13 supplied with a control current from the output 14 of the computer. An amplifier 15 supplies the motor in dependence on a second control circuit comprising a regulator, e.g. a foot pedal 16 adjusting a potentiometer 17 which changes its resistance in dependence of the position of the pedal. A switch 18 in series with the potentiometer is actuated for breaking the circuit when the pedal is in its upper end position. The control circuit is supplied with a low voltage V.sub.1 which passes via a resistor 19 to a change-over switch 23 and also to the input 20 of a comparator 21 having a second input 22 supplied with another low voltage V.sub.2 somewhat lower than the first said voltage. When the foot regulator is pressed down the voltage on the input 20 decreases and is less than the voltage V.sub.2, whereby a signal in the form of a logical "0" or "1" passes via a wire 24 to the input 25 of the computer. In the computer there is a logic circuit which on occurence of a "0" on the wire 24 supplies a control current via the wire 14 to the transistor so that the motor 11 can start by means of the foot regulator and the change-over switch 23 in the shown dash-line position.
On return of the regulator to the upper position the logical signal is "1", and the computer makes by controlling the change-over switch a change of the position of the switch to that shown by continuous lines. The voltage V.sub.1 provides via a voltage divider 26,27 a control voltage effecting a low, constant r.p.m. of the motor, and the machine runs slowly whereby a sensor 28 at the arm shaft of the machine detects the end positions of the needle. On a couple of wires 29, 30 from the sensor the logic circuits in the computer obtain signals when the needle is "up" or "down". When the regulator is returning in the upper position after a period of work, only the logical circuit for "needle up" is connected. The first signal for "needle up" occurring after such a return of the regulator when the machine runs slowly releases, in the computer, a break in the control current to the transistor 12 which makes the motor stop when the n
REFERENCES:
patent: 3636902 (1972-01-01), Matsubara et al.
patent: 4262614 (1981-04-01), Sugaya et al.
Husqvarna Aktiebolag
Miller Alfred E.
Nerbun Peter
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