JPH0133199B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a needle position detection device for a sewing machine, and in order to detect multiple needle positions, one detection device is used as a reference, and a pulse train is counted using this detection device as a reference position. By doing so, one or more other needle positions are detected.

Conventional needle position detection devices have been provided with independent position detection devices to detect, for example, the needle down position, the needle up position, and other needle positions, resulting in a complicated structure. In addition, since the needle position must be relatively changed with fine adjustment during assembly, the structure becomes even more complicated, which not only increases the price but also poses a major obstacle in downsizing the position detection device. It was becoming.

This invention was made in view of the above points,
When the number of pulses from a position detection device serving as a reference and a device that generates multiple (many) pulses per rotation of the main shaft of the sewing machine is counted, and the number of pulses reaches a preset number, that is, This is intended to detect a position that is different from a reference needle position by a predetermined rotation angle.

The details of this invention will be explained below with reference to the drawings.

FIG. 1 is a structural diagram of a needle position detection device showing an embodiment of the present invention, in which 1 is the main shaft of a sewing machine, 2 is a pulley of the sewing machine, 3 is a joint fixed to the pulley 2,
4 is a permanent magnet set that can be freely fixed to the joint 2 in the rotational direction, and 4a is a multi-pole magnetized ring-shaped permanent magnet, the magnetic poles of which are exposed on the circumferential surface. 4b is a permanent magnet magnetized in the direction of the main axis of the sewing machine, and 4c is a rotating body made of a non-magnetic material for holding these magnets. 5 is a cover of the detection device; 6 is a chassis that is fixed to the arm part of the sewing machine (not shown) and is used to assemble an electric circuit; 6a responds to the strength of the magnetic field created by the permanent magnet 4a, and generates a pulse train as the sewing machine rotates; A sensor 6b is located close to the permanent magnet 4b and detects the reference position, and a printed circuit board 6c constitutes a circuit for processing the electrical signals from the sensors 6a and 6b.

FIG. 2 shows an embodiment of the circuit configuration of the present invention, in which 10 is a terminal for inputting a reference position pulse from the sensor 6b, 11 is a terminal for inputting a pulse train from the sensor 6a, 12 is a counter, and 13 is a terminal for inputting a pulse train from the sensor 6a. A pull-up resistor, 14 a preset switch, 15 an exclusive OR element constituting a matching circuit, and 16 a 4
An input AND element, 17 an output terminal, and 18 an output terminal for a reference position pulse.

Next, the operation will be explained according to FIGS. 1 and 2.

The pulley 2 of the sewing machine is driven by a drive motor (not shown) via a belt. The magnet set 4 rotates from the pulley 2 via the joint 3, and permanent magnets 4a and 4b fixed thereto rotate. The permanent magnet 4b comes close to the sensor 6b only once per rotation of the main shaft 1 and generates one pulse signal. This pulse serves as a reference position pulse, and can be positioned freely depending on the mounting position of the magnet set 4. In addition, the magnetic poles of the permanent magnet 4a, which are exposed on its outer peripheral surface, are alternately close to the sensor 6a, and generate a plurality of pulse trains per rotation of the main shaft 1 (15 pulses in the example). . The reference position pulse obtained from the sensor 6b is input to the terminal 10 and output from the output terminal 18, and becomes a position detection pulse of the sewing machine, and for example, this pulse can be used as the needle down position pulse. This reference position pulse is also input to the clear terminal CL of the counter 12, and the counter 12
Let the outputs Q ₀ to Q ₃ be 0. After this, input terminal 1
The pulse train obtained by the sensor 6a is input to 1, and the counter 12 counts and outputs this pulse train.
Output in binary code to Q ₀ to Q ₃ . On the other hand, the preset switch 14 outputs the output _Q0 of the counter 12.
S ₀ to S ₃ are provided corresponding to Q ₃ , for example
If S ₀ = OFF, S ₁ = ON, S ₂ = OFF, and S ₃ = ON (0101 in binary code), the inputs of I _c0 to I _c3 of exclusive OR element 15 are connected to counter 12.
The outputs Q ₀ to Q ₃ and _the binary code 0101 signal from the preset switch 14 are input, and _the
is 1010 in binary code or 10 pulses in decimal
When counting, all the outputs of the exclusive OR element 15 become "1", and the output of the AND element 16 becomes "1" only at this time. This output "1" can be used as a sewing machine needle position detection pulse, for example, a needle top position pulse.

To summarize the above, the output of the reference position pulse from the sensor 6b is used as the needle down position pulse of the sewing machine, and from this needle down position pulse, the pulse train generated by the sensor 6a is counted, and a predetermined number of pulses set by the preset switch 14 is set. When this occurs, the pulse output from the AND element 16 is set to the upper position of the needle of the sewing machine.

As is clear from the above explanation, if you want to change the needle top position, for example, use the preset switch 1.
This can be easily done by simply changing the binary code set in step 4. Furthermore, in the embodiment, the pulse train of the sensor 6a is 15 pulses per revolution of the main shaft 1 of the sewing machine, but it is easy to increase the number of pulses, thereby improving the ability to resolve the needle position. can.

FIG. 3 shows an embodiment in which a reference position pulse obtained by the sensor 6b and two different position detection pulses are obtained, and 19 is a pull-up resistor;
0 is an exclusive OR element, 21 is a 4-input AND element, 22 is an output terminal, and 23 is a preset switch. By setting preset switches 14 and 23 to different binary codes, output terminal 1
7 and 22 different position detection pulses can be obtained.

FIG. 4 shows another embodiment of the pulse counting device, in which 24 is a pull-down resistor, 25 is a presettable down counter, CK is a pulse train input terminal,
LOAD is a signal input terminal for reading the binary code set by the preset switch 14. CL is an input terminal for initialization, and BR is a borrow output after counting down. The operation is similar to that of the circuit shown in Figure 2.
1010 (10 in decimal notation) is set, and then this 1010 is read into the presettable down counter 25 by the reference position pulse, and at the same time, internal initialization (reset) is performed. The previously preset 1010 is subtracted from the pulse train coming in from the input terminal 11, and when it reaches 0000, an output is obtained from the BR terminal. That is, an output is obtained when 10 pulses of the pulse train are counted, and the same output as the circuit diagram shown in FIG. 2 is obtained.

As explained above, according to the present invention, a needle position detection device for a sewing machine is made using a reference position pulse, a pulse train, and a counting device, and most of the position detection device is an electronic circuit, and the structure for changing the position is Since it is not necessary, it can be made smaller and cheaper. In addition, many current sewing machine drive motors have a speed control device and are equipped with a pulse generator to detect the rotational speed of the sewing machine, so the device that generates the pulse train required for this invention can be shared. Therefore, it can be made even more cheaply. Furthermore, when detecting a large number of needle positions, it is not necessary to increase the number of sensors, and a major feature is that this can be done only by the configuration of the electronic circuit.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of the main parts of a sewing machine showing an embodiment of the present invention, Fig. 2 is a diagram showing an embodiment of the circuit configuration of the invention, and Figs. 3 and 4 are circuits of the invention. It is a figure showing other examples of a structure, respectively. In addition, the same reference numerals in the figures indicate the same or equivalent parts, 1 is the main shaft of the sewing machine, 4 is the permanent magnet set, and 6 is the main shaft of the sewing machine.
is a chassis, 10 and 11 are input terminals, 12 is a counter, 14 and 23 are preset switches, 15,
20 is an exclusive OR element, 16, 21 are AND elements, 17, 18, 22 are output terminals, and 25 is a presettable down counter.

Claims (1)

[Claims] 1. A first pulse generator that generates one pulse per revolution in synchronization with the rotation of the main shaft of the sewing machine, and a first pulse generator that generates a plurality of pulses per revolution in synchronization with the rotation of the sewing machine. A second pulse generator that generates pulses, and a pulse counter that counts the pulses of this pulse train, and after this pulse counter is initialized (reset) by the pulses from the first pulse generator, The second pulse generator counts the number of pulses from the second pulse generator, and outputs a signal when a predetermined number of pulses are counted, and the second pulse generator is also used as the pulse generator for detecting the rotation speed of the sewing machine. needle position detection of the sewing machine, wherein the pulse from the first pulse generator is used as a first needle position detection signal of the sewing machine, and the output signal from the pulse counting device is used as a second needle position detection signal. Device. 2. The sewing machine needle position detection device according to claim 1, wherein the pulse counting device generates a plurality of different count outputs, each of which is used as a needle position detection signal.