JPS64222Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a control device for a sewing machine that has a pedal that can be operated with the front pedal and the rear pedal. The present invention relates to a device for extracting signals for control.

Conventionally, when a pedal is pressed forward to drive a sewing machine, a start signal is generated to detect the start-up state of the sewing machine in relation to the operation of the front foot to the initial position, and a start signal is generated to activate thread trimming means and presser foot lifting means. In order to do this, thread trimming signals and presser foot lifting signals are generated in conjunction with the rear pedal operation, but in the past, in order to detect these signals, switches such as limit switches and photo switches were installed in the pedal device. Since the switch is placed on the switch and the switch is turned on and off in connection with its operation, the signal is detected, which requires a large number of switches, increases the cost, and complicates the structure.The limit switch has poor durability, and the limit switch is prone to dust accumulation. There are disadvantages such as uncertainty in current flow and generation of noise.
Further, there was a drawback that operations such as position adjustment were complicated.

This invention aims to eliminate the above-mentioned conventional drawbacks.

An embodiment of this invention will be explained with reference to the drawings. A sewing machine 2 placed above a table 1 is connected by a belt 6 between a pulley 3 supported on a main shaft (not shown) and a pulley 5 of a motor 4 supported below the table 1. A pedal 8 is supported below the table 1 so as to be rotatable about a horizontal axis 7 from an intermediate position shown by solid line A in FIG. is maintained in balance by elastic force so that it is located at an intermediate position.
The lower end of a connecting rod 9 is rotatably supported at the tip of the pedal 8, and the upper end thereof is rotatably supported on the machine frame.The operating lever 10 is rotated by vertical movement of the connecting rod 9. and actuating lever 1.
A control body 11 that converts the amount of pedal operation into an electrical amount of change is connected to and arranged at 0.

The control body 11 maintains a low resistance value in relation to operating the pedal 8 in a rotation range Δt ₁ between the rear position C and the initial position B' which is slightly rotated in the direction of the front position from the intermediate position A. The first variable resistance R ₁ (fourth
) and a second variable resistor R ₂ (Fig. 4) whose resistance value changes in relation to the operation in the rotation range Δt ₂ between the initial position B' and the forward position B is arranged. There is.

The sewing machine 2 of this embodiment is provided with thread cutting means and presser foot lifting means (not shown), and both means are operated by separate electromagnets (not shown).

Next, the electric circuit of this embodiment will be explained.

The variable resistor R ₁ is connected between the power supply Vc and the ground.
Connect R ₂ separately. The first variable resistor _R1 changes its resistance value in proportion to the amount of pedal operation so that it has a small resistance value at the rear position C of the pedal and a large resistance value at the initial position B', and the second variable resistor
_R2 changes its resistance value in proportion to the manipulated variable so that it becomes a large resistance value at the initial position B' and a small resistance value at the forward position B.

The comparator circuit M connected to the contact of resistance R ₁ is low,
Resistance to three types of medium and high reference voltages X, M, and Z
Compare the output voltage r of R ₁ separately, and when the voltage V exceeds the reference voltages Y and Z, the output becomes L level, and when the voltage v decreases with respect to the reference voltage X, the output becomes L level. Parallel output x, y, z
occurs.

The pulse of the output x becomes a starting signal for starting the sewing machine, the pulse of the output y becomes a presser foot lifting signal that acts on the presser foot lifting means, and the output z becomes a thread cutting signal that acts on the thread cutting means.

The drive circuit D connected to the contact of resistance R ₂ is a resistance
Sewing machine motor 4 at a speed inversely proportional to the resistance value to _R2 .
In other words, the drive current to the motor 4 is controlled so as to drive the sewing machine at a speed proportional to the amount of forward depression of the pedal 8.

This invention has the above-mentioned configuration, and the pedal 8
At intermediate position A, where R1 is released, the output v of resistor _R1 is in a voltage state between reference levels X and Y,
Low resistance R ₂ becomes the maximum resistance value and the sewing machine stops.

When the pedal 8 is pressed forward, the output v of the resistor _R1 drops from the reference level X at the initial position B', and the output x of the comparator circuit M goes to L level, generating a start signal. When the front pedal is operated beyond the initial position B', the resistance value of resistance R ₂ decreases in proportion to the operation,
Thereby, the drive circuit D controls the drive current so as to drive the motor 4 at a speed inversely proportional to the resistance value.

When the pedal 8 is operated from the forward position to the rear position, the resistance value of the resistor _R2 reaches its maximum and stops the motor 4, and the output v of the resistor _R1 exceeds the reference voltage Y and then the reference voltage Z. , the output z of the comparator circuit M becomes the L level after the output y becomes the L level. Therefore, the thread trimming signal is generated after the presser foot lifting signal is generated.

Note that in this embodiment, the first variable resistor R ₁
The output v of is compared with three types of reference voltages X, Y, and Z in the comparison circuit M, but the number of signals to be output can be adjusted to the desired number by increasing or decreasing the number of reference voltages depending on the application. It can be done. Further, in this embodiment, the signals are used as signals for lifting the presser foot, thread trimming, and starting, but they may also be used for other purposes such as reverse stitching.

Furthermore, in this embodiment, the second variable resistor R ₂
The drive circuit D controls the drive current to the motor 4 so that it is driven at a speed that is inversely proportional to the resistance value of the motor 4, but as with the comparator circuit M, the output of the resistor _R2 is compared with multiple reference voltages. The speed may be controlled in stages.

Further, the motor may be one whose speed is controlled electrically, such as a DC motor or an electromagnetic clutch motor.

Furthermore, the resistances R ₁ and R ₂ may be either directly proportional or inversely proportional to the rotation angle of the pedal.

As described above, according to this invention, an operating signal for operating a predetermined operating mechanism of the sewing machine is detected in relation to a change in resistance value in relation to a front or rear pedal operation. Therefore, there is no need to place a switch in relation to the pedal as in the past, so the configuration is simplified, the number of parts is reduced, and costs are reduced.Furthermore, since detection can be performed only with a circuit, durability is improved and dust etc. It can always operate stably and accurately without being affected by noise, and the volume adjustment can be done using a circuit, which has the effect of improving efficiency.

[Brief explanation of the drawing]

Fig. 1 is a front view of the sewing machine of this embodiment, Fig. 2 is a side view of the pedal device, Fig. 3 is an explanatory diagram of the operation of the pedal, Fig. 4 is the electric circuit of this embodiment, and Fig. 5 is a time chart. It is.

Claims (1)

[Claims for Utility Model Registration] A motor connected to the main shaft of the sewing machine, an electrically actuated operating means connected to a predetermined mechanism of the sewing machine, one position C, the other position B separated from it, and an intermediate position between both positions. It is supported on the machine frame so as to be rotatable about a fixed straight line at position A, and is always supported by an elastic force that keeps it in the intermediate position, and can be rotated between the intermediate position and one position by pressing the heel, and can be operated by pressing the toe. In an industrial sewing machine having a pedal 8 which is rotatable between an intermediate position and the other position, the pedal 8 is rotatable between an initial position B' which is closer to the other position B than the intermediate position A of the pedal, and one position C. a first resistor _R1 whose resistance value changes according to the rotation angle, and a rotation angle provided corresponding to the rotation angle range between at least the initial position and the other position B of the pedal; A control body 11 is connected to the pedal and has a second resistor _R2 that changes its resistance value according to the rotation angle, and the control body ₁₁ is connected to the first resistor R1 to detect a resistance value corresponding to a predetermined rotation angle at the initial position. a detection circuit M that generates a signal to start the motor, detects a resistance value corresponding to a predetermined rotation angle on the one side C side from the intermediate position A, and generates a signal to actuate the actuating means; and a second resistor. A control device for a sewing machine comprising a drive circuit D that is connected to _R2 and controls the drive speed of the motor so that the motor is driven at a speed proportional to a change in the resistance value.