JPS5857080B2 - Sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for, for example, an industrial high-speed sewing machine, and particularly to a fixed position stopping device for the sewing machine.

Generally speaking, the fixed position stop device for this type of sewing machine uses a relay to obtain a stop signal for the sewing machine. Not only is the relay inoperable, but it is also prone to malfunctions because it is attached to a sewing machine that vibrates heavily, and the contacts wear out quickly, resulting in a shortened lifespan and reliability.

The present invention has been made with this point in mind, and it is an object of the present invention to provide a control device that can quickly and reliably obtain a fixed position stop signal for a sewing machine without using a relay.

That is, FIG. 1 shows one embodiment of this invention.
Reference numeral 1 indicates a needle position detector composed of a cam-shaped slip ring that rotates integrally with the drive shaft of the sewing machine, such as an upper shaft (not shown), and a brush in sliding contact with the slip ring. ” a switch to be operated; 3 is a transistor operated by a signal from the needle position detector 1;
4 is a comparator such as a voltage comparator that compares the output of an integrating circuit 6 to be described later with an input corresponding to the stop rotation speed of the sewing machine and outputs an output when the output of the integrating circuit 6 reaches a predetermined value; is a DC power supply, C1 is a capacitor connected to the collector of the transistor 3, R is a variable resistor that forms an integrating circuit 6 with the capacitor C1, and C2 is a voltage at the input terminal 4b of the voltage comparator 4 when the power is turned on. The capacitors R1-R5 that raise the voltage to the power supply voltage are fixed resistors.

The operation of the control circuit in the sewing machine of the present invention constructed as described above will be explained with reference to FIGS. 2 and 1.

Now, when the sewing machine is started (time t1 in Figure 2A), the number of rotations of the sewing machine gradually increases by depressing the treadle (not shown), and the sewing machine enters a high-speed operation state (time t2 in Figure 2A), and the machine returns to normal speed. When sewing is performed, the output terminal 4C of the voltage comparator 4 is held at the L level by turning the switch 2 on when starting the sewing machine.

At this time, a resistor R is connected to the transistor 3 from the DC power supply 5.
Since the base current flows through 1tR,2 and switch 2, this transistor 3 becomes conductive, and its emitter voltage is increased by DC power supply 5, resistor R1 and needle position detector 1 as shown in FIG. state.

In such a state, the collector of the transistor 3,
That is, a voltage as shown in the second diagram is applied to the input terminal 4a of the voltage comparator 4 by an integrating circuit 6 consisting of a capacitor C1 and a variable resistor VR.

On the other hand, to the reference input terminal 4b of the voltage comparator 4, a voltage divided by the resistors R3 and R4 is applied from the DC power supply 5, and at the same time, this voltage is applied to the reference input terminal 4b of the voltage comparator 4. and the collector voltage of the transistor 3 (FIG. 2D) applied to the input terminal 4a described above are compared by the voltage comparator 4.

In this state, since the voltage at the input terminal 4a is high, the output terminal 4c of the voltage comparator 4 goes to the L level, and since the switch 2 is turned on, the output terminal 4c is held at the L level. be done.

Next, in order to finish the sewing work by the sewing machine, the footboard (not shown) of the sewing machine is stepped back to the neutral position, and the sewing machine gradually enters a low-speed operating state (point 13 in FIG. 2A), and switch 2 is set to " OFF, but voltage comparator 4
Since the output terminal 4c of the transistor 3 is held at L level, the transistor 3 continues to be conductive.

Furthermore, as shown in FIG. 2A, the rotation speed of the sewing machine is lower than the neutral position, so the interval between the pulse widths of the needle position detector 1 becomes longer, and as a result, the collector voltage of the transistor 3 increases with respect to the capacitor C1. The discharge time of the capacitor C1 in the integrating circuit 6 including the variable resistor VR becomes longer.

Next, the potential across the capacitor C1, that is, the input to the input terminal 4a of the voltage comparator 4, is the input to the reference input terminal 4b of the voltage comparator 4 corresponding to the preset stopping rotation speed of the sewing machine. , the output of the voltage comparator 4 is inverted and the output terminal 4c becomes H level (Fig. 2A
At time t4), the transistor 3 whose base is connected to the output terminal of the voltage comparator 4 becomes non-conductive, and thereafter cuts off the input pulse from the needle position detector 1, and at the same time, as shown in FIG. As shown in FIG. 2, the H level output from the output terminal 4c of the voltage comparator 4 activates, for example, an electromagnetic brake (not shown) of a sewing machine.
This allows the sewing machine to stop at a predetermined position.

In the embodiment described above, the capacitor C2 connected in parallel to the resistor R3 is used to make the voltage rise at the input terminal 4b of the voltage comparator 4 at the same level as the rise of the power supply voltage 5 when the power is turned on. This can prevent the output 4c of the voltage comparator 4 from becoming a low potential.

In the embodiment described above, when it is desired to change the set rotational speed of the sewing machine by the integrating circuit 6, the variable resistor V
This can be easily done by changing the resistance value of R and changing the discharge time constant.

Furthermore, in the embodiment described above, the needle position detector 1
Although we have described the case where a transistor is used as the element for controlling the detection signal from the sensor, the same effect can be obtained by using other semiconductor switching elements such as Cyrisk or field effect transistor FET instead. Needless to say.

Further, although the above embodiments have shown an integrating circuit using a capacitor, it is sufficient if the periods can be compared.

Further, in the above embodiment, the switch 2 is operated in conjunction with the treadle of the sewing machine, but it is energized in response to the start and high-speed operation of the sewing machine, regardless of the treadle. Any switch that can be used will suffice.

Further, in the embodiment described above, the needle position detector 1 is constructed of a cam-shaped slip ring and a brush that is in sliding contact with the slip ring. A photoelectric non-contact switch, a reed switch, or the like may be used.

As described above, according to the present invention, there is provided a detector for detecting the needle position of the sewing machine, and a comparator for comparing the cycle of the detection signal of the detector with the set cycle corresponding to the stop rotation speed of the sewing machine. , a switch that is energized when the sewing machine is started and is running at high speed, and disables the comparator,
The above comparator is configured to be set to the initial value when the power is turned on, and the stop signal for the sewing machine is obtained from the output of the above comparator.This not only makes the stop signal for the sewing machine extremely accurate, but also enables the sewing machine to stop using the relay. This invention has an excellent effect in that it can provide an excellent control device for stopping a sewing machine at a fixed position without delay in operation time or malfunction due to vibration.

[Brief explanation of the drawing]

FIG. 1 is a control circuit diagram showing an embodiment of the present invention, and FIG. 2 is an operational waveform diagram of the control device of the present invention. In the drawing, 1 is a needle position detector, 2 is a switch, 3 is a transistor, 4 is a comparator, 5 is a DC power supply, and 6 is a capacitor C.
1 and a variable resistor VR, C2 is a capacitor, and R1-R5 are resistors.

Claims (1)

[Claims] 1. A detector for detecting the needle position of the sewing machine, a comparator for comparing the period of the detection signal of this detector with a set period corresponding to the stop rotation speed of the sewing machine, and a device for starting the sewing machine. and a switch that is energized during high-speed operation to disable the comparator, and is configured to set the comparator to an initial value when the power is turned on, and obtain a stop signal for the sewing machine from the output of the comparator. A sewing machine control device characterized by: 2 The comparator is a comparator that compares the output of an integrator circuit that integrates the detection signal of the detector with an input corresponding to the stop rotation speed of the sewing machine, and outputs an output when the output of the integrator circuit reaches a predetermined value. The sewing machine according to claim 1, further comprising a capacitor between one of the input terminals of the comparator and the power supply to set the comparator to an initial value when the power is turned on. control device. 3. The control device for a sewing machine according to claim 2, wherein the integrating circuit is constituted by a capacitor and a variable resistor. 4. The sewing machine control device according to claim 1, wherein the comparator is constituted by a voltage comparator. 5. The control device for a sewing machine according to claim 1, wherein the switch is a switch that is linked to the operation of a footboard of the sewing machine. 6. The control device for a sewing machine according to claim 1, wherein the switch is configured as a switch that is energized when the number of revolutions of the sewing machine exceeds a predetermined number of revolutions.