JPS6022958B2 - sewing machine safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for a sewing machine, and more particularly to a safety device in which a presser foot is raised and lowered through electric power means, and the sewing machine can only be started when the presser foot is in its lowered position. It is something.

When sewing with a sewing machine, especially if you are a beginner, you may make the mistake of inadvertently starting the sewing machine (while raising the presser foot).

In response to this problem, the main purpose of the present invention is to provide a safety measure that prevents the sewing machine from starting unless the presser foot is in a lowered state, and also includes The object of the present invention is to provide a technical means in which the lifting and lowering operations of the presser foot are carried out via electric power means, thereby reducing labor, and in which the above-mentioned safety objective means are provided in the configuration of the control circuit.

To explain the figure, a cam follower 3 is fixed to the middle of a presser foot 2 having a presser foot 1 attached to its lower end as usual.

The cam follower 3 is always urged downward by the pressure of a spring 4 wound around the presser bar 2 from above, and the cam contact branch 3a projected on one side of the cam follower 3 is always in sliding contact with the eccentric cam 5. The eccentric cam 5 is rotatably supported within the sewing machine arm 6, and is rotatably driven by a geared motor 9 via a pair of screw gears 7 and 8. The sewing machine is equipped with two IJ mitt switches that each generate a detection signal for circuit closing operation with the assistance of another lug 3b of the cam follower 3 to detect the normal raised position and lowered position of the presser bar 2. The limit switches are both regular type switches, and the actuator 10a of the limit switch 10 in the example above is mounted in the arm 6.
and the actuator 11a of the lower limit switch 11
In the middle between the two where the ear piece 3b does not touch either of them,
Both switches are in the OFF state, and at this time, the presser bar 2 is in an operating state in which it is ascending or descending. If the lug 3b touches the IJ mitt switch on either the upper or lower side and turns it on, the lifting and lowering operation will be paused, but in order to start it, push it to an appropriate position on the front of the sewing machine arm 6 where it can be easily operated. A wholesale switch 12 is installed. In addition, there is a connection cord 14 from a foot controller 3, which is not shown in FIG.
A controller box turtle 5 is provided in the sewing machine arm 6 and houses a control circuit for starting and stopping the gear mode 9 in forward and reverse directions in response to each signal input from the controller box 15. I'm sending out Codeblind 6. The control circuit is explained with reference to Fig. 2.The power supply circuit 7' rectifies the AC power supply blade 8 and supplies power to the positive and negative busbars 99 and 211. The sewing machine motor 22 provides speed control.The input signal means for providing speed control to the sewing machine motor 22 is via the potentiometer turtle 3a in the foot controller box 3; The analog switch 23 is inserted, and only when the analog switch 23 is in the conduction control state as shown in the figure, speed control is given to the sewing machine motor 22 in accordance with the usual depression of the foot controller 13. In the case of conduction, power is not supplied to the sewing machine motor 22 regardless of the operation of the foot controller 3. For example, a field effect transistor or the like is used as the analog switch 23, and the sewing machine motor speed control means in the power supply circuit 7 is For example, S
Use CR method etc. Upper and lower glue mitt switch 1071
Each working output terminal of 1 is connected to a reset type flip-flop 2.
4 and two inputs of the NOR element 25.

), the upper limit switch IQ is flip-flop 2.
When the set input of No. 4 is entered and the flap is turned on, the set operation causes an output to be generated on the Q output side. Similarly, the lower limit switch 11 is connected to the reset input of the flip-flop 24, and when reset by its ON signal, produces an output at the 9 output terminal. The gear motor 9 is
It rotates either forward or backward depending on the positive or negative direction of the power supply, and the positive or negative direction of this power supply must be selected and controlled.
, a gear motor 9 is connected to the center of the cross-connected combination of four transistors 26 to 29. Therefore,
When the flip-flop 24 is in the set state and outputting Q, among the four transistors 26 to 29, the transistor 26 and the transistor 2 are connected to the geared motor 9.
9 is controlled to be electrically conductive so that a current can flow in the direction of the arrow A shown in the figure. However, since this cross-type motor rotation direction control circuit is connected between the busbars 19 and 20 in series with a transistor for switching control, the above-mentioned operation is performed only when the three fins of the transistor are in the conductive state. The power is supplied in the direction of arrow A as shown in FIG. In fact, at this time, the direction of rotation of the geared motor 9 is set in advance so that the eccentric cam 5 rotates to lower the presser foot 2; "When the lower limit switch turtle 1 is in the ON state due to contact with the ear piece 3b, the flip-flop 24 is in the reset state. If three transistors are also suitable for conduction, in this case, the flip-flop 24 is The transistor 27 and the transistor 28 are made conductive by the 9 output, and the gated motor receives B.
A current is applied in the direction of the arrow, and the rotation direction of the eccentric cam 5 at this time is such that the presser foot 2 is pushed up. NOR
The element 25 produces an AND output when both of its two inputs are OFF, and the base of the above-mentioned switching transistor 30 is connected to the t output side. As this switching input, the working output terminal of the push-pin switch tortoise 2 and the output of the AND element 31 are similarly connected. One of the two input terminals of the AND element 31 is connected to the Q output of the flip-flop 24 mentioned above, and the other is connected to the comparator 3.
The two output ends are connected to each other. The comparator 32 has one input connected to a predetermined positive potential point 33, and the other input connected to the potentiometer 13 of the foot controller 13 described above.
The variable potential of a is connected, and the potentiometer 13
When the potential on the side a exceeds that of the positive fixed potential point 33, an output is generated and the gate of the AND element 31 is opened. With the above configuration, its operation will be explained below.

In the state shown in the second figure, the presser bar 2 is at rest in the lowered position, and at this time, the lower limit switch 11 is in the ON state due to the contact of the ear piece 3b, that is, the state of each switch shown in the second figure. Correspondingly, as mentioned above, the flip-flop 24 is in the reset state and cannot operate because the transistor 30 is still non-conducting, but the geared motor 9 is oriented so that current can flow in the direction of arrow B. It is in a prepared state. When you want to raise presser foot 1 with this), press push button switch I.
When 2 is pressed to turn ON, the geared motor 9 receives power in the direction of arrow B due to conduction of the transistor 30, and its rotation rotates the biased cam 5 and starts pushing up the cam follower 3. Then, when the ear piece 3b opens the lower limit switch 11 to OFF, the NOR element 25
Both inputs are turned OFF and their AND output is applied to the base of the transistor 30. Therefore, even if the push button switch 12 is manually released and turned OFF a little after the presser foot 2 starts rising, the gear motor 9 continues to be driven. m) maintained. When the end of the required upward stroke is approached and the ear piece 3b comes into contact with the upper limit switch 10 and turns on, the output of the NOR element 25 disappears, the transistor 30 becomes non-conducting, and the gear motor 9 stops.
That is, the presser bar 2 rests in the raised position. At the same time, the flip-flop 24 is inverted to the set state, and the conductivity states of the four assisting transistors are inverted so that the motor is supplied with power in the direction of arrow A at the next start. Similarly, when lowering the presser foot 1, press the presser switch 12 to turn it on.
In response to this, the transistor 30 becomes conductive, and the geared motor 9 is driven to rotate in the opposite direction as described above, and as soon as the presser bar 2 begins to descend, the upper limit switch 10 is turned on.
returns to OFF, and similarly, the AND output from NOR element 25 acts to maintain conduction of transistor 30, and the lowering operation stops when lower limit switch 11 turns ON. As mentioned above, ``In order to raise or lower the presser foot 1, in any case, the push button switch 12 is only pressed briefly, and after that, the lifting operation to a predetermined rest position is automatically controlled. However, the present invention further has the following characteristic effects.

That is, when attempting to lower the presser foot 2 from the raised state, the presser foot 2 can also be lowered by depressing the foot controller 13 instead of turning on the push button switch 12. When the foot controller 13 is depressed and the output potential of the potentiometer 13a exceeds the other fixed input potential of the comparator 2, the comparator 32 is in the output state, and the upper limit switch 10 is in the ON state before the presser foot 1 starts lowering. "The Q outputs of the flip-flop 24 are both connected to the AND element 3.
1, and the AND output makes the transistor 30 conductive, so the guard motor 9 starts the operation for lowering the presser foot in exactly the same way. After starting, the lowering operation is maintained by the NOR element 25 in exactly the same way, and the lowering of the presser foot 1 continues until the flip-flop 24 is reversed to reset by the detection signal of the lower limit switch 11, at which point the reset AND element 31 becomes non-output, the lowering operation is stopped. Furthermore, in this case, even if the controller 3 is continuously depressed, while the lower limit switch 11 is in the OFF state, the analog switch 23 is in a non-conducting state, that is, the presser foot 1 is in the lowered position. The control signal for controlling the speed of the sewing machine motor 22 is not applied to the speed control input terminal 21 of the power supply circuit 17 unless the sewing machine motor 22 is started and the presser foot 1 is lowered. The foot controller 13 only has a normal speed control function.Therefore, even if you accidentally press the foot controller 13 with the presser foot 1 raised, the sewing machine will not start. As mentioned above, the safety device of the present invention significantly reduces fatigue during sewing work by reducing the operation for raising and lowering the presser foot through electric power means. Yes, and when I tried to start the sewing machine with the presser foot inadvertently raised while I was working on it, it would not start straight away,
In that case, the presser foot that you forgot to lower starts to descend.

Once the presser foot has finished lowering, the sewing machine motor can be controlled again using the foot controller. This is extremely convenient in terms of reducing the labor involved in sewing work and preventing operational errors.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of the mechanism of the apparatus of the present invention, and FIG. 2 is an electric circuit diagram. 1...presser foot, 2...presser bar, 3...
...Cam floor, 5...Eccentric cam, 9...Gard motor (electric power means), 10...Upper limit switch, 12...Push button switch, 13...
- Foot controller, 17... Power supply circuit (including sewing machine motor speed control circuit), 21... Sewing machine motor speed control input terminal, 22... Sewing machine motor, 2
3...Analog switch, 22-30...Each element of the start/stop control circuit (24...Flip-flop, 25...NOR element, 26-29...Motor rotation direction Control transistor group ``30...Switch transistor group'', 31...AND element ``
32... Comparator. Figure 1 Figure N Rudder

Claims (1)

[Claims] 1 The presser bar of the sewing machine is raised and lowered by a cam rotated in either direction via electric power means, and the upper and lower movements generate a detection signal at each predetermined raised rest position and lowered rest position of the presser bar, respectively. a start/stop control circuit comprising a limit switch and a push button switch for starting operation, the push button starts the electric power means, and each detection signal from the limit switch stops the operation of the electric power means; circuit means for providing a downward start control to the start/stop control circuit in response to depression of the foot controller when the presser bar is in the ascending rest position; and a sewing machine motor controlled by the foot controller only when the presser bar is in the descending rest position. A safety device for a sewing machine, comprising circuit means for applying a control signal to a sewing machine motor speed control circuit.