1. Field of the Invention
The present invention relates to a sewing machine with improved structure and constitution, and more particularly to a sewing machine in which a retainer adapted to retain a material to be sewn can move along an X-axis and a Y-axis.
2. Description of the Prior Art
When it is necessary to extend the sewing range of conventional sewing machines, in particular in the Y-axis direction (forward or backward direction), the arm on which the head portion of the sewing machine is installed had to be elongated forward. This causes a problem in that the elongated arm occupies a considerable space.
Moreover, when the arm is elongated, the center of gravity of the sewing machine is positioned at a front portion thereof This makes it difficult to maintain the balance of the sewing machine. Accordingly, there has been a request for a construction capable of reducing the space occupied by the sewing machine while easily maintaining the balance of the sewing machine.
An example of such conventional sewing machines is given in FIG. 1. FIG. 1 shows a side elevation view of a conventional sewing machine disclosed in Korean Patent Application No. 1999-0015717, the content of which is incorporated herein for reference (reference numerals presented hereinafter to explain FIG. 1 apply to FIG. 1 only). Referring to FIG. 1, the conventional sewing machine has a head portion 202 elongated toward the front side of its body 203 by means of an arm 201. The longer the material to be sewn is in the Y-axis direction (forward or backward direction) as retained on a retainer 204 atop a table 200, the longer the arm 201 needs to be.
As the arm 201 becomes longer, the head portion 202 becomes farther from the body 203. This makes the center of gravity of the sewing machine positioned at the front portion thereof Consequently, the body 203, having the arm 201 connected thereto, is subject to additional weight and torsion due to the lengthened arm 201. It results in a problem in strength of the machine. Therefore, there has existed a demand for a sewing machine making it possible to minimize or eliminate the length of an aim 201 for the purpose of avoiding any damage to its body 203 and, at the same time, to extend the sewing area in the X-axis direction (leftward or rightward direction) and/or Y-axis direction of the sewing machine.
Meanwhile, conventional sewing machines employ single driving motor to drive both a needle and a shuttle race body, as shown in FIG. 2. Referring to FIG. 2, a single driving motor 230 is adapted to drive an upper shaft 210 for driving a needle 205, as well as a lower shaft 220 for driving a shuttle race body (not shown in the drawing).
The driving motor 230 is connected in a line with the upper shaft 210. The lower shaft 220 is positioned below a table 200 and is parallel to the upper shaft 210. A rotation transfer means 240, such as a timing belt, is used to enable the single driving motor 230 to drive both the upper and lower shafts 210 and 220.
Such a simultaneous driving of the upper and lower shafts 210 and 220 necessitates the interconnection and coupling of them within the arm 201 and the body 203. When the arm 201 and the body 203 need to be removed to extend the sewing area in the Y-axis direction, as mentioned above, the simultaneous driving of the upper and lower shafts 210 and 220 cannot be implemented. Therefore, it is necessary to solve such problem and, at the same time, to provide an improved construction accordingly.