JPS63279879A - Cloth pressing control apparatus of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a sewing machine having a presser foot which is normally pressed down onto a cloth placement surface such as a throat plate by an elastic force, in which the presser foot is moved by an electromagnet. The present invention relates to a presser foot control device for a sewing machine for raising and lowering the presser foot.

[Prior art] In order to place the cloth below the presser foot before sewing, it is necessary to separate the presser foot above the cloth placement surface, and an electromagnet is energized to apply the elastic force to the presser foot. After the cloth is pulled up and placed, the electromagnet is deenergized and the elastic force lowers the presser foot onto the cloth placement surface.

[Problem to be solved] However, if the electromagnet is deenergized when the presser foot is lowered, the presser foot will fall rapidly onto the fabric placement surface due to its elastic force, causing a collision between the top surface of the presser foot and the fabric placement surface. There was a risk of damaging the upper surface of the presser foot or damaging various parts of the presser foot mechanism due to impact.

Further, if there is an object to be sewn between the presser foot and the cloth placement surface, especially if the object is velvet or thin cloth, there is a risk that the cloth may be damaged in the event of a collision.

EPurpose of the Invention This invention solves the above problems by lowering the presser foot by controlling the energization of an electromagnet so that when the presser foot is lowered, the descending speed is faster at the beginning of the descent and slower at the later stages of the descent. do.

[Embodiment] The sewing machine in this embodiment is a cycle sewing machine such as a buttonhole sewing machine, and the mechanical parts of the presser foot and its elevating mechanism are the same as those of the conventional ones, and therefore, the explanation thereof will be omitted.

In Fig. 1, 1 is an operation detection circuit that generates a presser foot lifting signal when the pedal is pressed and a presser foot lowering signal when the pedal is released, and 2 is connected to a presser foot (not shown) and is applied to the presser foot when energized. This is an electromagnet that applies an upward force to the presser foot that resists the downward elastic force applied to the presser foot. 3 is an electrical box disposed in a predetermined part of the sewing machine, MC is a well-known microcomputer disposed inside the electrical box 3, and D
R is a drive circuit that supplies and cuts off DC energizing current to the electromagnet 2 based on commands from the microcomputer MC.

The microcomputer MC controls the energization of the electromagnet based on the flowchart for lowering the presser foot shown in FIG.

In the flowchart of FIG. 2, when a presser foot lowering signal is generated from the operation detection circuit 1 (step-1), the presser foot is placed slightly above the position where the presser foot contacts the cloth placement surface (for example, 5II11).
The energizing current to the At electromagnet 2 is cut off for a predetermined period of time until the At electromagnet 2 descends to the top (steps 2 and 3).

After passing, the energizing current is supplied to the mold magnet 2 for a predetermined time Att (steps-4, 5), and after the elapse of At1, it is cut off again for a predetermined time At2 (steps-6, 7). Repeat steps 4-7 the number of times determined by the counter inside the CPU (
Steps 4-9). This invention has the above-mentioned structure, and when a presser foot lowering signal is generated by the pedal release operation, the presser foot quickly drops to the front of the cloth placement surface and then slowly descends to lower the cloth as shown in FIG. 3A. The mounting surface is in contact with the cloth above it.

Note that the length of the predetermined time At can be adjusted by the operator according to conditions such as the thickness of the cloth and the strength of the downward elastic force.

[Effects] As described above, according to the present invention, unlike the conventional lowering movement of the presser foot shown in FIG. The sewn products are not wasted, and the machine is prevented from being damaged by falling impact, thereby extending the life of the mounting device. ′

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the control circuit of this embodiment, Fig. 2 is a flowchart for lowering control, Fig. 3A is an explanatory diagram showing the lowering operation of the presser foot of this embodiment, and Fig. 3B is FIG. 3 is an explanatory diagram showing a conventional lowering operation. Figure 1 Figure 2 Start Stellar Ruff'1 Trivial゛ 00-Stellaf:
2 Oste, Boo 3, t n. Figure 3A h'5

Claims (1)

[Scope of Claims] A presser foot that can move toward and away from the cloth in an upward direction by receiving a force that presses it against the surface on which the cloth is placed due to an elastic force; In a sewing machine that has an electromagnet that rises when the presser foot is lowered, the control circuit that controls the excitation of the electromagnet is configured so that when the presser foot is lowered, the lowering speed is faster at the beginning of the lowering.
A presser foot control device for a sewing machine characterized by controlling excitation so that it becomes slower in the latter half of descending.