JPS609476B2 - position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position detection device that can be used to detect the position of a sewing needle in an electric sewing machine.
When automatically stopping the needle (hereinafter referred to as the needle) at a lower level or higher level, or performing each operation of thread loosening, thread trimming, and thread sweeping, the function detects the needle position suitable for each of the above operations. The object of the present invention is to obtain a detection device that can perform detection using one detector.

In general, electric sewing machines detect that the needle is in the lower layer (hereinafter referred to as "needle down detection"), detect that the needle is in the upper layer (hereinafter referred to as "needle up detection"), and detect that the needle is in the upper layer (hereinafter referred to as "needle up detection"). Detection of a defect that may initiate each operation of (
(hereinafter referred to as area detection).

Conventionally, three detection elements have been used to perform the three types of detection described above, but this has the drawback that the detection section is complicated and large.

The present invention detects each point with a single photodetector by changing the shape of a light shielding plate attached to a motor shaft so as to rotate together with the sewing machine shaft at positions corresponding to the respective detection positions, By detecting the needle position suitable for each of the above-mentioned operations, the conventional drawbacks are eliminated and the structure of the needle position detection device for an electric sewing machine is simplified.

Hereinafter, the present invention will be explained with reference to the drawings showing one embodiment thereof.

1 is a circular, almost dish-shaped light shielding plate, and a square hole 2 is provided on its circumferential surface from point A to point A', and from point B to point C.
A notch 3 is formed throughout.

A portion of the light shielding plate 1 at point A' functions to detect the needle down, and a portion at point B functions to detect the needle up, and from point A' to point C.
The part functions as area detection. The light shielding plate 1 is directly connected to a shaft 5 of a sewing machine driving DC motor (hereinafter referred to as a motor) 4 and rotates in the direction of arrow R. 6 is a photodetector consisting of a pair of a light emitting element and a light receiving element; 7 is an electromagnetic brake coil;
Reference numeral 8 denotes a rotary plate made of a magnetic material, and the rotary plate 8 is mounted so as to compete with the shaft 5 of the electric motor 4 and to be movable only in the direction of the shaft 5.

Reference numeral 9 denotes a sewing machine shaft coupled to the shaft 5 of the electric motor 4 via a coupling.

When the electric motor 4 rotates, the circumferential surface of the light shielding plate 1 attached to the shaft 5 rotates between the light emitting element and the light receiving element of the photodetector 6, and between points A and A' and between point B and point Between C, light is transmitted from the light emitting element to the light receiving element, and in other parts, the transmission of the light is blocked to generate an electrical signal. Furthermore, when the electric motor 4 is disconnected from the power source and both ends of the armature are short-circuited, dynamic braking is activated, and when voltage is further applied to the electromagnetic brake coil 7, the rotating plate 8 is attracted to the electromagnetic brake coil 7, and the electric motor 4
This applies brakes to stop the vehicle. FIG. 3 is an electric circuit diagram of the position detection device of the present invention, in which 10 is a light receiving element of the photodetector 6, and 11 is a NOT logic element (hereinafter referred to as NOT).
, 12 and 13 are monostable multipipulators (hereinafter referred to as MM), and 14 and 15 are NAND logic elements (hereinafter referred to as NAND
), 16 is a D flip-flop (hereinafter referred to as D-FF), and 17 is an R-S flip-flop (hereinafter referred to as RS-FF).
18 is a switch. Further, S is an input signal to the MM13 which changes its state when the needle stops in the lower layer. The light receiving element 10 is installed in the photodetector 6 shown in FIG. 1, and receives light between points A and A' and between points B and C while the light shielding plate 1 rotates. Element 1
0 is ○N and other parts are OFF,
NOTI 1, MM1 2, NAND14 and D-F
F1 6 constitutes the detection section of the needle lower layer and the needle upper layer,
The MM 13, RS-FF 17, and NAND 15 constitute an area detection section, and the switch 18 is operated by a pedal of the sewing machine.

Next, the operation diagram of FIG. 4 will be explained based on FIG. 1, FIG. 2, and FIG. 3. FIG. Figure c is NAND1 4
The figure d shows the Q output P4 of the D-FF, the figure e shows the Q output P5 of the MM13, the figure f shows the Q output P6 of the RS-FF17, and the figure g shows the switch 1-8 side of the NAND15. Input P7 and h' in the figure are output P8 of NAND15.

Proceeding with the explanation according to the operating order of the sewing machine, first, when the power is turned on, the RS-FF1
7, its Q output P6 becomes a low potential L, and its Q output becomes a high potential state. Output P4 is the needle lower layer and needle upper layer detection signals, and these two signals are required after the sewing machine has made at least one rotation (after sewing one stitch), and D-FF16 is preset at the needle lower pupil. , there is no preset when the power is turned on.

Output P8 is an operation signal for thread loosening, thread trimming, and thread sweeping, and operates at a low potential L, but when the power is turned on, the Q of RS-FF17
Since the output P6 is at a low potential L, the output P8 is kept at a high potential, and even if the switch 18 is opened by operating the pedal, the above operation is not performed. When the pedal is pushed forward, the sewing machine runs, and when the pedal is released, dynamic braking is activated to slow down the machine.

FIG. 4 shows the time when this dynamic braking is released after it has worked: Uto, needle lower layer stop time t, thread loosening, thread trimming,
These are the waveforms of the above-mentioned main part of the circuit diagram of FIG. 3 at time t2 when the pedal is operated for thread sweeping operation, time t3 when area detection ends, and time t4 when the needle upper calendar stops. As shown in FIG. 4a, a square wave pulse train having a low potential L between points AA' and CB is obtained in one light receiving element. In MM12, in synchronization with the falling part of this pulse train,
A pulse train having a high potential for the operating time T of the MM 12 is obtained. A signal obtained by extracting only the overlapping portion of the high potential portion of both signals is generated by the NAND 14, and the D-FF 16 is preset by this signal. Thereafter, the D-FF 16 inverts its output at the rising edge of the CK input signal (point B in FIG. 4a), and a signal as shown in FIG. 4d is obtained. This signal rises at point A' (needle lower layer) and falls at point B (needle upper layer), and the lower needle layer and the upper needle layer are detected by this signal. In other words, the circuit (third
(not shown in the figure), the needle lower layer can be detected and the motor can be stopped. The same goes for detecting the needle upper layer and stopping the electric motor, and this is done by sensing the first descending portion after thread loosening, thread cutting, and thread sweeping operations. Next, area detection will be explained.

The MM13 operates in synchronization with the stoppage of the needle lower layer of the sewing machine, and produces a signal at the Q output P5, which is at a low potential L for the operating time T2, as shown in FIG. 4e.

The RS-FF17 is set by this signal, and its Q output P6 becomes a high potential day, and the signal of the switch 18 that issues thread loosening, thread trimming, and thread removal signals (high potential H) is NANDed.
15 to the output P8. As the electric motor 4 rotates, when the point C of the light shielding plate 1 passes the photodetector, the RS-FF 17 is reset and the Q output P6 becomes a low potential L state, and the signal of the switch 18 is is the output P8
can no longer be transmitted. After detecting the lower layer of the needle in this way, the time ratio of point C of the light shielding plate 1 passing through the photodetector 6 is 3.
The switch 18 can be used to loosen the thread, cut the thread,
Thread sweeping operation becomes possible. However, before operating the switch 18, for some reason the stop position was changed to point A on the light shielding plate 1.
'C, Q output P of RS-FF17
6 is at a low potential L, even if the switch 18 is operated,
It will not work at all, and MM13, RS-FF1
7. The NAND 15 has a stopping position at point A' on the light shielding plate 1.
This is to confirm that the area is between C, that is, to detect the area.

In the above embodiment, a light shielding plate and a photodetector were used as the needle position detector, but the same effect can be obtained by using a detector with a combination of a magnet lead switch, a brush and a slip IJ ring, etc. instead. There is.

As is clear from the above embodiments, the position detection device of the present invention has a shield plate that rotates together with the sewing machine shaft.
forming a signal passing section or a signal shielding section between C;
One detector is provided corresponding to this shielding plate, the lower layer of the sewing machine needle is made to correspond to the point A', the upper layer of the sewing needle is made to correspond to the point B, and the thread loosening, thread cutting, and thread wiping The position range of the sewing needle that enables each operation to be started is made to correspond between the points A'C, and the output signal of the detector changes the state at each of the points A, A', B, and C. a circuit that generates a signal that changes state only between
This device is equipped with a circuit that generates a signal that changes the state only between C and C. Since one detection element can detect multiple predetermined positions of the sewing machine needle, the detection device is simplified, and the detection element The size of the mounting position can be reduced by 4 mm, which has an excellent practical effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway side view of a position detection device showing one embodiment of the present invention, FIG. 2a is a perspective view of a light shielding plate of the same top layer detection device, and FIG. FIG. 3 is a developed view of the main parts of the surrounding green part of the light shielding plate, FIG. 3 is an electric circuit diagram of the same layer detection device, and FIG. 4 is a signal waveform diagram of each part of the circuit.

A, A', B, C...point, 1...light shielding plate (shielding plate),
2... Square hole (signal passing section or signal blocking section)
, 3... Notch (signal passing part or signal blocking part), 6... Photodetector (detector), 9...
...Sewing machine shaft, 16...D flip-flop (
17...R-S flip-flop (circuit that generates a signal that changes state only at points A' and B), 17...RS flip-flop (point A'
and a circuit that generates a signal that changes state only at point C).

Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 Between points AA' and B on the shielding plate that rotates with the sewing machine shaft.
Forming a signal passing section or a signal blocking section between C,
A detector is provided corresponding to this shielding plate, and the lower position of the sewing machine needle corresponds to the point A', the upper position of the sewing needle corresponds to the point B, and each of the The position range of the sewing needle that enables the sewing needle to start its operation is made to correspond to the points A'C, and the output signal of the detector that changes the state at each of the points A, A', B, and C causes the point A' A circuit that generates a signal that changes state only between points B and the point A.
1. A position detection device comprising a circuit that generates a signal that changes state only between 'C' and 'C'.