JPS6044959B2 - sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sewing machine control system having a function of stopping a sewing machine at a predetermined needle position, particularly two different positions, based on a needle position signal corresponding to the needle position of the sewing machine. Related to equipment.

In normal sewing work, sewing starts when the sewing machine pedal is first depressed.Next, when the pedal is returned to the center position, the needle stops at the position where it touches the fabric (needle down position), and then the pedal is depressed. When the sewing machine returns, the needle stops at the position where it has come out of the fabric (needle top position), and thread trimming is performed while the sewing machine is running, leading to a series of sewing machine operations such as pulling out the sewn product from the sewing machine.

Conventionally, the above-mentioned positioning means for stopping at the needle down position or stopping at the needle up position detects both of the above two positions with a needle position detector attached to the sewing machine pulley and is controlled according to the detection signals. was common.

FIG. 1 shows an example of a conventional needle position detector. In FIG. 1, a bearing holder 1' holds an outer ring of a bearing that supports a needle position detector shaft (not shown) attached to a sewing machine pulley, and is fixed on the stationary side.

On the other hand, a magnet plate 3' having a magnet 2', and this magnet 2
Magnet plates 5' having magnets 4' attached so as to have opposite polarities to '' are movable independently in the rotational direction, and the needle position detector is controlled by a magnet plate holder 6' and a set screw 7' It is fixed to the shaft and is configured to rotate as the sewing machine rotates. The bearing holder 1'' also includes a magnetically sensitive element 8'' such as a Hall IC that generates a signal in response to the magnet 2'', and a magnet 3'' having a different polarity from the magnet 2''. A built-in magnetically sensitive element 9'' is attached to the magnetically sensitive element 8'' in a front and reverse relationship so as to generate a signal in response to only the magnetically sensitive element 8''. '' is configured to generate signals according to the positions of the magnetic plates 3'' and 5'' as the sewing machine rotates. Here, when the magnet plate 3'' is fixed in the needle down position and the magnet plate 5'' is fixed in correspondence with the needle up position, the needle down position signal is sent from the magnetically sensitive element 8'', and the needle down position signal is transmitted to the magnetically sensitive element 9''. From then on, operations are performed to generate a needle up position signal.

According to yet another method different from the above, one magnetically sensitive element such as a Hall element that generates a positive or negative output voltage with respect to both polarities of the magnet is used instead of the magnetically sensitive elements 8'' and 9''. There are some that have built-in.

Conventionally, the needle position has been detected using a combination of two magnetic plates and two magnetically sensitive elements, or a combination of two magnetic plates and one magnetically sensitive element, as described above. Generally, a system has been adopted in which needle position stop control is performed based on a needle position signal.

However, in the above conventional method, two magnetic plates and two magnetically sensitive elements are required to detect the needle positions at two locations in the former case, and one magnetically sensitive element is required in the latter case. However, if an amplification circuit to the required signal level or a microcomputer is used, it is impossible to apply positive and negative voltages, and the position signal must be converted into a position signal with the same polarity voltage. Both systems require a complex and expensive signal conversion circuit. The present invention eliminates the above-mentioned drawbacks, provides an inexpensive needle position detector by making the needle position detector extremely simple, and provides a sewing machine control device that satisfies conventional control functions. It's hot,
When a microcomputer is used as the control element, the effect is most noticeable because it can be achieved only by software processing.

According to the present invention, the configuration of the needle position detector is extremely simple, for example, by combining only one magnetic plate for detecting the needle down position and one magnetically sensitive element such as a Hall IC. become what is done. An embodiment of the present invention using the needle position detector constructed as described above is shown in FIGS. 2 to 4, and the present invention will be described below with reference to FIGS. 2 to 4.

An embodiment of the invention is shown in block diagram form in FIG.

In FIG. 2, reference numeral 1 detects the position of the sewing machine pedal, and outputs a speed setting signal S corresponding to the amount of pedal depression, and a pedal depression signal ■.
, or a pedal sensor circuit that generates the pedal-back signal Vu, 2 represents a needle position detector that generates the needle down position signals ■ and D, and 3 corresponds to a frequency generator in digital speed control, for example, and In terms of control, it represents a so-called pulse generator, which corresponds to a device that further converts the output of the speed generator into pulses, and generates a plurality of pulses for each rotation of the sewing machine. “Furthermore, 4
5 represents a microcomputer that controls the operation of the sewing machine according to the various inputs mentioned above, 5 represents a speed control circuit that performs speed control, and 6, 7, and 8 are drivers for the clutch coil 9, brake coil 10, and thread trimming solenoid 11, respectively. represents. The motor has an electromagnetic clutch/brake structure, and the rotational force of the motor is controlled by controlling the currents of the clutch coil and brake coil and changing the torque of each lining surface (not shown) through each magnetic circuit. This is transmitted to the sewing machine and controls the speed. First, when the sewing machine pedal is depressed, the pedal sensor circuit 1 generates a depression signal ■. is output to the microcomputer 4, which outputs an output signal V8 and controls the speed control circuit 5 to receive the speed setting signal.
Make it possible. In such a state, when the pedal sensor circuit 1 outputs a speed setting signal Vs according to the depression of the sewing machine pedal, the speed control circuit 5 outputs the speed setting signal Vs, which is attached to the shaft end of the sewing machine. The driver 6
, 7 to clutch coil 9 and brake coil 10.
It operates to control the speed and drive at a constant speed according to the amount of pedal depression. Next, when the peggle is set to neutral, the microcomputer 4 sets the output signal ■Ss to 0FF.
Then, the low speed setting signal ■,, is output, and the sewing machine shifts to the low speed operating state.

In such a low speed operating state, when the needle down position signal VND is output from the needle position detector 2 next, the microcomputer 4 sets the low speed setting signal LS to 0FF,
A signal BR is output for a certain period of time, and the speed control circuit 5 operates to turn off the crack coil 9 and turn on the brake coil 10 based on the signal BR, and the sewing machine stops at the needle down position. . Next, if the pedal is pressed back and the pedal sensor circuit 1 outputs the pedal depression signal Vu and the needle down position signal ■ND is generated, the microcomputer 4 outputs the low speed setting signals ■ and L, and the Start low-speed operation in the same manner as above, and turn on the signal VTR.
is output and the thread trimming solenoid 11 is set to 0 via the driver 8.
Turn to N and start thread trimming.

In the above case, if the needle down position signal ND is not generated, an interlock is established such that the pedaling back signal Vu is invalidated, and therefore the thread trimming is always triggered by the needle down position signal ND. It can be said that the process starts from the position where ND occurs.

The sewing machine is started as described above, and the needle down position signal ~,
When the end of , is detected, the microcomputer 4 starts counting the pulse signals from the pulse generator 1 input to its interrupt input terminal (INT terminal), and counts the pulse signal at the position where the predetermined number is reached. (hereinafter referred to as the thread trimming end position), the low speed setting signal ■ is set to 0FF, the signal ■BR is output for a certain period of time, and the brake coil 10 is
is set to 0N to stop the sewing machine, and the signal ■TR is set to 0.
FF and thread trimming solenoid 11 to 0F via driver 8.
Press F to finish thread trimming.

Here, as described above, the pulse generator 3 represents a device that converts the output signal of the speed generator into a pulse, and therefore, this output pulse is a position pulse generated in response to the rotation of the sewing machine. If this position pulse is an angle A with equal intervals, and the count value is Rn, then the thread trimming end position is a position separated by (AxPn) from the end position of the needle down position signal 4D.

However, the thread cutting end position varies from 00 to AO depending on the adjustment position of the magnet plate, but by increasing the number of pulses per revolution, it is possible to reduce the angle A, which is practical. On the other hand, even if the relative positional relationship between the thread trimming end position and the needle lower position is fixed as described above, there is no problem in practice. Among the above-mentioned operations, in particular, the operation from depressing the sewing machine pedal back to stopping at the thread trimming end position (hereinafter referred to as thread trimming process) is shown in a flowchart in FIG. 3, and will be explained below with reference to FIG.

First, the thread trimming start conditions are determined at steps 21 and 22, and if the stepping back signal Vu is output and the needle down position signal ■NO is output, then the low speed signal ■, L is output at 23 and low speed operation is started. At the same time, the signal ■TR is output at 24 to attract the thread trimming solenoid.

Furthermore, the internal counter area is cleared at 25, the end of the needle down position signal VND is waited for at 26, and the count start flag FCS is set at 27. At this point, the external interrupt condition 31 is satisfied, and therefore 32 starts counting pulses from the pulse generator, and each time an interrupt input is received, the counter is incremented by one count. The value of this counter is a constant value (Pn
), the condition 33 is satisfied and the process 34 is performed, that is, the count start flag FCS is reset, and
The count end flag lower CE is set to indicate that the thread cutting end position has been reached. The count end flag FC
When E is set, the condition of 28 is satisfied, the signal TR of 29 becomes 0FF, and the thread trimming solenoid becomes 0FF.
At step 30, the signal BR is output for a certain period of time T1, the brake coil is turned ON, the sewing machine is stopped, and the thread cutting process is completed.

The above-mentioned operation can be expressed as a time chart as shown in FIG. 4.

Signal 9 in FIG. 4 represents the pulse output signal from the pulse generator.

The detection of the thread cutting end position will be briefly described below.
First, at the same time as the end of the needle down position signal (point A), counting of the pulse output signal 9 is started, and by counting a prescribed number Pn, the thread trimming end position is detected (point B).
, the thread cutting process ends at this thread cutting end position as described above.

In this way, the thread trimming end position (point B) is determined at a constant relative angular position from the end position of the needle down position signal.

Here, it is clear that even if the above-mentioned point A is used as the starting position of the needle down position signal, the thread trimming end position can be detected in the same manner as described above.

As is clear from the above description, the present invention has a simple configuration in which the needle position detector can detect only one position,
Using the needle position signal from this needle position detector as a reference, other needle positions are detected by counting the number of pulses from a pulse generator that generates a large number of pulses depending on the rotational position of the sewing machine. The pulse generator is based on the idea of trying to detect In some cases, it can be handled relatively easily using only software, and therefore, the hardware configuration of the control device hardly needs to be changed, and the price can be significantly reduced by simplifying the configuration of the needle position detector. As a result, the cost of the sewing machine drive system as a whole can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a front view of a needle position detector of a conventional sewing machine control device, FIG. 2 is a block diagram of a sewing machine control device showing an embodiment of the present invention, and FIG. 3 is a front view of a needle position detector of a conventional sewing machine control device. FIG. 4 is a float chart showing the operation of the cutting process, and FIG. 4 is a time chart showing the operation of the sewing machine control device of the present invention, particularly the thread cutting process. 1... Pedal sensor circuit, 2... Needle position detector, 3... Pulse generator, 4...
・Microcomputer, 5... Speed control circuit, 6, 7, 8... Driver, 9...
Clutch coil, 10...Brake coil, 11
...Thread cutting solenoid.

Claims (1)

[Claims] 1 A sewing machine, a motor for driving the sewing machine, a needle position detector that generates a first needle position signal corresponding to a first needle position as the sewing machine rotates, and a needle position detector that detects the speed of the sewing machine or the motor. The sewing machine comprises a pulse generator that includes a speed generator that detects and outputs a speed detection signal, converts the speed detection signal into a rectangular wave pulse signal, and outputs it, a speed setting device, and a control device that controls the sewing machine. The device includes means for starting counting of the square wave pulse signals using the first needle position signal as a reference, and a second pulse signal is counted at a position where the number of pulses counted by the means reaches a predetermined value. The needle position is detected, and the speed of the motor is controlled according to the deviation between the speed setting signal and the speed detection signal or the rectangular wave pulse signal using a drive command and a speed setting signal from the speed setting device. The stop control to the first needle position is performed by removing the drive command from the speed setter, and the stop control to the second needle position is performed by driving the motor at a low speed by the slow speed drive command. sewing machine control device.