JPS5950352B2 - Sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a sewing machine, and particularly relates to the lowering operation of a presser foot at the start of sewing and the drive timing of the sewing machine.

[Background of the invention]

Sewing machines that have been known for a long time are configured to manually lower the presser foot at the beginning of sewing.

However, in operations where starting and stopping are frequently repeated, manually raising and lowering the presser foot is very troublesome and causes considerable fatigue to the operator. On the other hand, there is a method in which the presser foot is automatically raised and lowered by an electric signal obtained from a front foot switch or the like.

In this case, it is extremely dangerous if the sewing machine starts even though the presser foot has not descended, so a sewing machine that starts the sewing machine after the presser foot has completely lowered is proposed. has been done. The sewing machine described in US Pat. No. 2,906,221 also falls within this technical scope. However, when this sewing machine shuts off the pedal switch,
Since the presser foot is configured to always return to the upper position, the sewing machine is not suitable for sewing several times in succession in a very short period of time (stitching) because the time required for the work is long. [Object of the Invention] The present invention improves safety by preventing the sewing machine from operating until the presser foot securely presses the cloth even if there is a front tread signal. The aim is to provide a sewing machine that has

[Summary of the Invention] The present invention has a delay circuit that delays an output signal for driving a sewing machine based on a signal from a front pedal depression in accordance with the time when the presser foot descends, and the output of the delay circuit causes the It is equipped with circuit means for validating an output signal for driving the sewing machine, and when a forward depression signal from the pedal is received in a state where the presser foot is lowered after the delay time of the delay circuit has elapsed; The sewing machine is equipped with a circuit means for immediately outputting an output signal for driving the sewing machine to immediately drive the sewing machine, and is configured to prevent danger and perform the sewing operation at high speed.

[Embodiments of the invention]

Hereinafter, a circuit configuration of an embodiment of the present invention will be described based on FIG.

LSW-P becomes ``H'' level when the sewing start command switch is turned ON with the sewing start command signal.

KLT-P becomes ``H'' level when the presser foot is raised according to the presser foot signal. NANDI to NAND3 are inverted logical product integrated circuits (hereinafter referred to as NAND circuits), INVI
, INV2 are inverters, and NOR is an inverted OR integrated circuit (hereinafter referred to as a NOR circuit). LSW-P and KLT
- P are each connected to an input of a NAND circuit NANDI. The output of the NAND circuit NANDI is the NAND circuit N
connected to one of the inputs of AND2, the NAND circuit NAND
The outputs of 2 and NAND3 are each NAND circuit NAND3.
, and one of the inputs of NAND2. The output of NAND circuit NAND3 is inverter INV2, variable resistor V
It is connected to the base of the transistor TR via R. A NAND circuit NAND is installed at the collector of the transistor TR.
It is connected to one of the inputs of No. 3 and to the positive terminal Vcc of the DC power supply via a resistor R, and its emitter is grounded. The base is grounded via a capacitor C. The LSW-P signal via the inverter INVI and the output of the NAND circuit NAND2 are connected to the input of the NOR circuit NOR, and the output DRIVE-P is given a rotation instruction to the sewing machine at the "H" level and the sewing machine starts sewing.The following describes the operation. explain.

The presser foot is raised, that is, the presser foot signal KLT-P
is "H" and when the sewing start command switch is turned on, the sewing start command signal LSW-P becomes ``H'' level, and the output of the NAND circuit NANDI becomes ``L'' level.

At the same time, a presser foot signal is sent to lower the presser foot using a circuit not shown. KLT-P goes to the ``L'' level, and the output of the NAND circuit NANDI immediately returns to the ``H'' level. When the output of the NAND circuit NANDI is at the ``L'' level, the output of the NAND circuit NAND2 is at the ``H'' level, and the output of the NAND circuit NAND3 is at the ``L'' level. Nando circuit NAN
Since the output of D2 is at ``H'' level, even if the sewing start command signal LSW-P is at ``H'' level, the other input of the NOR circuit is at ``L'' level, so the output signal DRIVE- P is not output and the sewing machine does not start rotating immediately. When the output of the NAND circuit NAND3 goes to the 'L' level, the output of the inverter INV2 goes to the 'H' level, and the capacitor C starts to be charged via the variable resistor VR, and the base voltage of the transistor TR gradually rises to a certain level. When the value reaches this value, the transistor TR becomes conductive and the collector is grounded and becomes the "L" level.Transistor TR
The collector of is connected to the input of the NAND circuit NAND3, so when the collector goes to the "L" level, the output of the NAND circuit NAND3 goes to the "H" level, and the output of the NAND circuit NAND2 goes to the "L" level. Since both inputs of the NOR circuit NOR become ``L'' level, the output signal DRIVE-P becomes ``H'', instructing the sewing machine to rotate, and the sewing machine begins to rotate and sew cloth. As described above, after a certain period of time has elapsed since the sewing start command signal LSW-P reaches the ``H'' level, the output signal changes to ``H''.
The level is reached and the sewing machine rotates and begins sewing. This delay time is determined by the time constant of the variable resistor VR and the capacitor C, and if it is changed arbitrarily by the value of the variable resistor VR, the sewing start command signal L
Even if the time from when the SW-P is inserted to when the presser foot is completely lowered is different, the sewing machine will not start rotating before the presser foot is fully lowered, or the sewing machine will not rotate even when the presser foot is fully lowered. , you can set the optimal sewing start time. In addition, the presser foot lowering signal KLT-P is output.
After the delay time of the delay circuit including variable resistor VR, capacitor C, etc. has elapsed, one input terminal of the NOR circuit becomes ``L''.

Under this condition, if you step on the front pedal switch, the LSW-
P becomes ゛゛H, and NO is output through the inverter INVI.
Since the other input terminal of the R circuit becomes "L", the output signal DRIVE-P is applied from the NOR circuit, and the sewing machine starts immediately. Therefore, it is possible to reliably tread and tread sewing while the presser foot is lowered. [
[Effects of the Invention] As described above, according to the present invention, when there is a sewing start command signal, the sewing machine starts after the presser foot is reliably lowered, so it is very safe. Since the sewing machine starts immediately when the switch is operated, it is possible to easily perform treadle sewing.

[Brief explanation of drawings] Figure] shows a control circuit according to an embodiment of the present invention.

Claims (1)

[Claims] 1. An industrial sewing machine that has a means for automatically raising the presser foot after the end of sewing, and a means for giving a lowering command to the presser foot using an electric signal, and the sewing machine is driven by a pre-depression signal of the pedal, Circuit means having a delay circuit for delaying an output signal for driving the sewing machine based on the front-depression signal of the pedal in accordance with the time when the presser foot is lowered, and enabling a driving signal for the sewing machine by the output of the delay circuit. and in a state where the presser foot is lowered after the delay time of the delay circuit has elapsed, when a front depression signal from the pedal is received, an output signal for driving the sewing machine is immediately output, and the sewing machine is 1. A control device for a sewing machine, comprising circuit means for immediately driving the control device.