JPS6124956B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hazard prevention device for an electric sewing machine, and more particularly to a hazard prevention device for an electric sewing machine that prevents dangers caused by erroneous operation when turning on the electric sewing machine.

FIG. 1 shows an example of the configuration of a power transmission mechanism in an electric sewing machine.

In FIG. 1, a clutch friction plate CLM is attached to the output shaft MI of a motor M. A shaft CLB1 of a clutch plate CLB disposed opposite to this clutch friction plate CLM is rotatably supported by the brake friction plate BKM via a bearing AH and movable in the axial direction of the motor M, and is attached to the other end of this shaft CLB1. is a pulley
PL is installed. Above clutch friction plate
A clutch coil CL is provided near the CLM, and a brake coil BK is provided near the brake friction plate BKM.

From the above pulley PL to the sewing machine shaft (not shown),
Power is transmitted through the belt VB. Therefore, either the clutch coil CL or the brake coil BK is energized to energize the clutch plate CLB and the clutch friction plate.
By pressing against either the CLM or the brake friction plate BKM, the pulley PL rotates or stops, transmitting and cutting off power to the sewing machine shaft, and controlling the operation and stopping of the sewing machine. It is.

The excitation control of the clutch coil CL and brake coil BK is performed in an electric sewing machine where the electric sewing machine is started and stopped by pedal operation.
The drive command signal from the pedal operation is input, and for external signal type electric sewing machines, the drive command signal from the foot switch etc. is input, and the IC
This is done using logic circuits and microcomputers.

When using the power transmission mechanism of an electric sewing machine configured as described above, if a drive command signal is input by mistake when the power switch (not shown) is turned on, the sewing machine will not be able to operate. Ru. That is,
Since sewing machines use needles, it is extremely dangerous for the sewing machine to start operating without the will of the operator.
Conventionally, in order to prevent this type of danger, a method has been used in which the sewing machine is operated by detecting the rising edge of the input of the drive command signal. This method will be explained as follows based on the operating waveforms shown in FIG.

FIG. 2a shows the rise of the power supply voltage _V1 . When the power switch is turned on at point A, the power supply voltage _V1 gradually rises to a voltage V at which the IC logic circuit can operate at point C. Figure b shows the rise of the drive command signal, and points C and H are points where the rise of the input of the drive command signal is detected. When the drive command signal is input at the same time as the power switch is turned on at point A and reaches point C, the power supply V ₁ has not yet reached the voltage V at which the above-mentioned IC logic circuit can operate, so the rise of the drive command signal is It is not detected and the sewing machine is not operated. However, when the drive command signal is inputted again at two points, the rising edge of the drive command signal is detected at point H, and the sewing machine starts operating.
As described above, in the conventional prevention method, when a drive command signal is applied and then a power switch is turned on, the first erroneous operation can be prevented, but the next erroneous operation cannot be prevented. On the other hand, the control of recent electric sewing machines has become more sophisticated and is becoming more automated. For example, in the case of a sewing machine equipped with a sewn object detection device that detects the sewn object using light, the output of the sewn object detection device is used as the drive command signal, so if the power is turned on by mistake with the sewn object inside, this will be prevented the first time. However, if the sewn object is removed from the sewn object detection device against the will of the user of the sewing machine and is detected by the sewn object detection device again, the sewing machine will be operated.

The present invention has been made in view of the above-mentioned conventional problem, and its purpose is to provide an electric sewing machine that does not operate if a drive command signal is input at the same time or before when the power is turned on. The aim is to provide safety equipment for preventing dangers.

In order to achieve the above object, the present invention provides a command signal detection circuit that detects whether or not a command signal is given to the sewing machine when a power switch is turned on; an upper position detection circuit that detects the upper position of the sewing machine; If the power switch is turned on at the same time or after the sewing machine command signal is given based on the output of each detection circuit, by inputting the needle rise command signal,
The present invention is characterized by the provision of a danger prevention circuit that allows the electric sewing machine to be driven until the needle reaches the upper position, and prohibits continuous operation of the sewing machine thereafter.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 3 is an electric circuit in which the same parts as in FIG. 1 are denoted by the same reference numerals. In FIG. 3, the collector of transistor T ₁ is connected to the positive terminal of power source V ₂ (hereinafter referred to as power source V ₂ ) through clutch coil CL, and similarly, the collector of transistor T ₂ is connected to the positive electrode of power source V ₂ through brake coil BK. The emitters of the transistors T ₁ and T ₂ are connected to the negative terminal of the power supply V ₂ .

The base of the transistor _T1 is connected to the output terminal of a NOR integrated circuit (hereinafter referred to as a NOR) _NOR2 through a resistor _R6 . The base of the transistor _T2 is connected to the output terminal Q of the monostable multivibrator MM through a resistor _R7 .

When the foot switch FSW connected to the positive terminal of the power supply for IC logic circuits (hereinafter referred to as power supply V ₁ ) is stepped forward, its movable piece S is connected to the fixed contact S _{1, and when it is stepped backwards, the above-mentioned movable switch is connected to the fixed contact S 1} . The piece S is connected to a fixed contact _S2 , and the movable piece S is connected to a fixed contact N when the foot switch FSW is set to neutral.

Lower position detector DN that detects the lower position of the sewing machine needle
The output is L when the sewing machine needle is in the lower position.
(low level). Further, the upper position detector UP, which detects the upper position of the sewing machine needle, outputs L (low level) when the sewing machine needle is located at the upper position. The output terminal of the lower position detector DN is connected to the input terminal 1 of a logical product integrated circuit (hereinafter referred to as logical product) _AND1 . The other input terminal 2 of this AND ₁ is connected to the N contact of the foot switch FSW and one end of a resistor _R2 , and the other end of this resistor _R2 is connected to the negative pole of the power supply voltage _V1 . There is.

The output terminal of the above AND ₁ is the negative OR
It is connected to the input terminal 1 of NOR ₁ and the input terminal 1 of NOR ₃ . The input terminal 2 of the NOR NOR ₁ is the input terminal 2 of the NOR NOR ₃ ,
The fixed contact _S1 of the foot switch FSW, one end of the resistor _R3 , the reset terminal R of the flip-flop _FF1 and the input terminal of the inverter _INV1 are connected, and the other end of the resistor _R3 is connected to the power supply voltage _V1. It is connected to the negative terminal of.

The output terminal of the above inverted logical sum NOR ₃ is the input terminal 1 of the logical sum integrated circuit (hereinafter referred to as logical sum) OR ₁
Input terminal 2 of this logical sum OR ₁ is a negative logical sum.
The output terminal of NOR ₄ is connected, and the output terminal of the above-mentioned logical sum OR ₁ is connected to input terminal B of monostable multivibrator MM.

The input terminal 1 of the NOR NOR ₄ is connected to the output terminal of the flip-flop FF ₁ , and the input terminal 2 is connected to the output terminal 3 of the NOR ₁ and the output terminal of the AND ₂ . Negative OR of the above
The output terminal of NOR ₁ is connected to the input terminal 1 of NOR ₂ . In addition, the output terminal Q of the flip-flop FF ₁ is connected to the input terminal 1 of the logical product AND ₂ .
Similarly, an upper position detector UP is connected to input terminal 2. Set terminal S of flip-flop FF ₁
One end of the resistor _R1 is connected to the fixed contact _S2 of the foot switch FSW, and the other end of the resistor _R1 is connected to the power supply voltage _V1.
It is connected to the negative terminal of.

The output terminal of inverter INV ₁ is NOR ₅
The other input terminal 2 of NOR ₅ is connected to one end of a resistor _R4 , a diode _D , and a capacitor _C1 through a resistor R5. The other ends of the resistor R ₄ and the diode D are connected to the positive pole of the power supply voltage V ₁ , and the other end of the capacitor C ₁ is connected to the negative pole of the power supply voltage V ₁ . Negative disjunction NOR ₅
The output terminal of is connected to the set terminal S of flip-flop _FF2 . The output terminal Q of the flip-flop _FF2 is connected to the input terminal ₂ of the NOR2. Reset terminal R of flip-flop FF ₂
is connected to the output terminal of the inverter INV ₂ , and one end of each of a resistor R ₉ and a capacitor C ₂ is connected to the input terminal of the inverter INV ₂ through a resistor R ₈ . The other end of the above resistor _R9 is a capacitor connected to the positive terminal of the electrode voltage _V1 .
The other end of _C2 is connected to the negative pole of the power supply voltage _V1 .

In addition, in the figure, the part SSS surrounded by a broken line constitutes a danger prevention circuit when a drive command signal is input when the power switch is turned on.

The circuit according to the embodiment of the present invention has the above-mentioned configuration, and its operation will be explained below.

If the power switch is turned ON without the foot switch FSW being pressed before, that is, with no drive command signal being input, the inverter INV ₂ will be connected to the input terminal for a time t ₁ determined by the resistor R ₉ and the capacitor C ₂ . is L
(Low level) Its output terminal becomes H (High level), and the reset terminal R of flip-flop FF ₂ becomes H.
The output terminal Q becomes L. After the above time t ₁ has elapsed,
The output terminal of the inverter _INV2 becomes L, and the reset terminal R of the flip-flop _FF2 becomes L.

On the other hand, during time t ₂ determined by resistor R ₄ and capacitor C ₁ , input terminal 2 of NOR ₅ is L, and time t ₂
After the elapse of , the input terminal 2 becomes H. Also, as mentioned above, the foot switch FSW is not depressed, so the fixed terminal _S1 is L, so the inverter
The input terminal of INV ₁ is L and its output terminal is H, the output terminal of NOR NOR ₅ is L, and the set terminal S of flip-flop FF ₂ is L. Then,
The output terminal Q of the flip-flop FF ₂ is at L, and the input terminal 2 of the NOR NOR ₂ is at L. The above is an explanation of the operation of the danger prevention circuit SSS.

Here, when the foot switch FSW is pressed forward to set the fixed contact S ₁ to H, the negative OR NOR ₁ becomes H, the output terminal is L, and the NOR is
In NOR ₂ , input terminal 1 becomes L and its output terminal becomes H. Therefore, the transistor _T1 becomes conductive and the clutch coil CL is excited, and the clutch plate CLB is pressed against the clutch friction plate CLM as explained in Fig. 1, and the sewing machine is driven via the pulley PL and the belt VB. Ru. In this case, the foot switch FSW
Since the fixed contact N of is L, the output terminal of the logical AND ₁ becomes L. Since input terminal 2 of NOR ₃ is H and input terminal 1 is L, its output terminal is L. Also, flip-flop FF ₁ has output terminal Q
is L and the output terminal is H, so the negative OR
In NOR ₄ , input terminal 1 becomes H and output terminal becomes L.
Therefore, the output terminal of the logical sum _OR1 also becomes L, the output terminal Q of the monostable multivibrator MM also becomes L, the transistor _T2 is non-conducting, and the brake coil BK is not excited.

Next, set the foot switch FSW to the neutral fixed contact N.
When connected to the fixed contact N and set it to H, the negative OR
NOR ₁ causes input terminal 2 to be L, but logical product AND ₁
Input terminal 2 is at H, and input terminal 1 is also at H until the sewing machine needle is at the lower position. Therefore, the above logical product
Since the output terminal of AND ₁ becomes H, the negative OR
In NOR ₁ , input terminal 1 is H and its output terminal is L. Therefore, in NOR ₂ , input terminals 1 and 2 are L and its output terminal is H, and the clutch coil CL continues to be excited. Therefore, the sewing machine continues to rotate.

Then, when the sewing machine needle comes to the lower position, the output terminal of the lower position detector DN becomes L, the output terminal of the AND ₁ also becomes L, and the clutch coil CL is no longer excited, and at the same time, the NOR ₃ Both input terminals 1 and 2 become L, and their output terminal becomes H. For this reason, the monostable multivibrator MM operates for a certain time and with its output signal the transistor
_T2 is made conductive to excite the brake coil BK, and the clutch plate CLB is pressed against the brake friction plate BKM to apply the brake and stop the sewing machine needle in the lower position. At this time, the output of flip-flop FF ₁ does not change, so NOR ₄ and AND ₂
is in the same operating state as before.

This time, when the foot switch FSW is pressed backwards and the fixed contact _S2 is set to H, the set terminal S of flip-flop _FF1 becomes H, its output terminal Q becomes H, and the same becomes L, and the AND ₂ becomes the input terminal. Both 1 and 2 are H
Therefore, its output terminal becomes H. For this reason,
The input terminal 3 of NOR ₁ becomes H, and the clutch coil CL is excited and the sewing machine is driven, so the sewing machine needle moves from the bottom to the top. When the sewing machine needle reaches the upper position, the output of the upper position detector UP becomes L, and the input terminal 2 of the AND ₂ is set to L.
Therefore, the output terminal becomes L, and at the same time the clutch coil CL is no longer excited, the negative OR
The output terminal of NOR ₄ becomes H, and the output terminal of OR ₁ also becomes H, and the monostable multivibrator MM
operates for a short time, and the brake coil
Energize BK and apply the brake to stop the sewing machine in the upper position.

By sequentially operating the foot sewing machine switch FSW in the forward, neutral, and reverse directions as described above,
A sewing machine performs predetermined operations.

Next, the circuit operation of the danger prevention circuit SSS when the power switch is turned on with the foot switch FSW being depressed will be explained. When the power switch is turned on as described above, the reset terminal R of the flip-flop _FF2 becomes H for a time _t1 , and its output terminal Q becomes L. At the same time, the input terminal 2 of the negative OR NOR ₅ becomes L for a time t ₂ . Furthermore, this time
It is necessary that t ₂ be longer than time t ₁ .

On the other hand, the foot pedal FSW is pressed forward and has a fixed contact.
S ₁ is H, the input terminal of the inverter INV ₁ is H and its output terminal is L, and the input terminals 1 and 2 of the NOR NOR ₅ are both L and its output terminal is H. Therefore, the set terminal S of flip-flop _FF2 becomes H, and its output terminal becomes H. Therefore, the input terminal ₂ of NOR2 becomes H, and the output terminal becomes L, so that the transistor _T1 cannot conduct and the clutch coil CL is not excited. Also,
The above flip-flop FF ₂ has one power switch.
Unless it is turned OFF and turned ON again, it will not be reset and its output terminal Q will continue to hold H, so even if the foot switch FSW is returned to neutral and the foot switch is pressed forward again, the sewing machine will not be driven. Therefore, turn on the power switch.
This provides highly reliable protection against erroneous operations when turning on the power.

FIG. 4 shows a second embodiment of the apparatus of the present invention, in which the same parts as in FIG. 3 are denoted by the same reference numerals. In FIG. 4, the logical AND ₁₀ is a new component not shown in FIG. The input terminal 1 of this AND ₁₀ is connected to the fixed contact S ₁ of the foot switch FSW, one end of the resistor R 1, and the input terminal of the inverter _{INV 1 ,} and the resistor R ₁ is connected to the input terminal of the inverter INV 1.
The other end is connected to the negative pole of the power supply voltage _V1 . Input terminal 2 of the above AND ₁₀ is a flip-flop
Connected to the output terminal of FF ₂ , and the output terminal of this logical product AND ₁₀ is connected to the reset terminal R of flip-flop FF ₁ , the input terminal 1 of NOR ₃ , and the logical OR
Connected to input terminal 2 of _OR10 .

The above logical sum OR ₁₀ is replaced with the negative logical sum NOR ₁ in the example in Figure 3, and its input terminals 1 and 3
The respective connections are the same as in FIG. In this Figure 4, the negative logical OR NOR ₂ in the example in Figure 3 is removed, and the negative logical OR
The output terminal of NOR ₁ is connected to the transistor through resistor R ₆ .
It is connected to the base of T ₁ .

In addition, the danger prevention circuit SSS surrounded by the broken line in Figure 4
The configuration is exactly the same as the example in FIG. 3, except that the connection of the output terminal of flip-flop FF ₂ is different.

The second embodiment of the present invention has the above configuration, and its operation will be explained below. foot switch
When FSW is not pressed and the power switch is turned on, the output terminal of flip-flop _FF2 becomes H. When the foot switch FSW is pressed forward in this state, the fixed contact S ₁ becomes H, the input terminals 1 and 2 of the logical sum AND ₁₀ become H, and therefore the output terminal becomes H, and the subsequent operation is The operation is similar to the example in FIG. 3 above.

On the other hand, when the foot switch FSW is depressed and then the power switch is turned on, the output terminal of flip-flop FF ₂ is L, the input terminal 1 of AND ₁₀ is H, and its input terminal 2 is L, which is the output terminal. becomes L, and the sewing machine is not driven.

If the sewing machine needle is not in the upper position when the foot switch FSW is reversely depressed, the sewing machine is driven until the sewing machine needle is in the upper position, that is, until the output of the upper position detector becomes L.

In this embodiment, the sewing machine does not operate with the first drive signal when the foot switch FSW is pressed forward, and the sewing machine needle can be driven to the upper position with the second drive signal when the foot switch FSW is pressed backwards, and the sewing machine can be taken out. There is.

Fig. 5 shows a third embodiment of the present invention in which the same parts as in Figs. Although this is a connected method, the same effect can be obtained by using software on a microcomputer CPU.

Although the above-mentioned embodiments have been described with respect to electromagnetic clutch type sewing machines, other types of direct drive type sewing machines such as those in which a direct current motor is directly connected to control the drive and stop, or other types may also be used.
This is effective for all electric sewing machines controlled by IC logic circuits, and similar effects can be obtained.

As described above, according to the present invention, it is possible to reliably prevent the risk of the electric sewing machine operating inadvertently due to an error in the order of operations, and it is also possible to obtain the effects of facilitating the removal of the sewn product.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the power transmission mechanism in an electric sewing machine, Fig. 2 is an operating waveform diagram in the conventional danger prevention method, Fig. 3 is an electric circuit diagram according to the first embodiment of the device of the present invention, and Fig. 4 5 is an electric circuit diagram according to a second embodiment of the apparatus of the present invention, and FIG. 5 is an electric circuit diagram according to a third embodiment of the apparatus according to the present invention. In each figure, the same parts are given the same symbols, M is the motor, CLB is the clutch plate, M is the clutch friction plate, BKM is the brake friction plate, CL is the clutch coil, BK is the brake coil, PL is the pulley, DN is a lower position detector, UP is an upper position detector, FSW is a foot switch, S ₁ , N and S ₂ are fixed contacts corresponding to forward, neutral and reverse pedals of the foot switch FSW, respectively, T ₁ , T ₂ is a transistor, R ₁ to R ₁₁ are resistors,
D is a diode, V ₁ is a power supply for IC logic circuit, V ₂ is a power supply, SSS is a danger prevention circuit, AND ₁ ,
AND ₂ and AND ₁₀ are logical product integrated circuits,
OR ₁ and OR ₁₀ are OR collector circuits and NOR ₁ , respectively.
~NOR ₅ is a NOR integrated circuit, respectively,
INV ₁ , INV ₂ are inverters (inverter circuits), FF ₁ ,
FF ₂ is a flip-flop, and MM is a monostable multivibrator.

Claims (1)

[Scope of Claims] 1. In an electric sewing machine equipped with a drive means for driving the sewing machine using a motor as a drive source, and a control circuit for controlling this drive means by a command signal to drive and stop the sewing machine, when the power is turned on, A command signal detection circuit detects whether a sewing machine command signal is given, an upper position detection circuit detects the upper position of the sewing machine needle, and a sewing machine command signal is given based on the output of each of the detection circuits. If the power switch is turned on at the same time or after, the electric sewing machine can be driven until the needle reaches the upper position by inputting the needle raise command signal, and a danger prevention circuit is installed that prohibits continuous operation of the sewing machine thereafter. A danger prevention device for electric sewing machines characterized by the following. 2. A danger prevention device for an electric sewing machine according to claim 1, characterized in that the control circuit is constituted by a microcomputer.