1. Field of the Invention
The present invention relates to a special path generating device. Particularly, this invention is a device that can produce double circular path. In addition, it generates a constant-speed circular movement. It is easy to control. Plus, its volume is small.
2. Description of the Prior Art
There are many traditional path generating devices. Referring to FIG. 1, it is the typical X-Y plotter. It has a working surface 71, working slide 72, a Y-axis sliding assembly 73 and an X-axis sliding assembly 74. The working slide 72 can slide on the Y bar 731 of the Y-axis sliding assembly 73. Furthermore, this Y-axis sliding assembly 73 can slide on the X bar 741 of the X-axis sliding assembly 74. Therefore, by utilizing a controller (not shown), the moving path of the working point 721 of the working slide 72 can be controlled. For example, it can generate a circular path or other specific path.
The disadvantages of the above-mentioned conventional device are described as follows. This device needs two driving sources. The degree of freedom is 2. Besides, it is required to input precise X-Y coordinates information. If the user wants to obtain a smooth curve, this curve must be generated by several straight lines (connected together to obtain a proximal one). In fact, it is hard to control it very precisely. In addition, the controller needs complicated computation and conversion (into many X and Y axis moving commands). So, the operation of the entire system is quite complicated.
Another traditional special path generating device, as shown in FIG. 2, is a polishing machine for optical fibers. It includes a polishing (or grinding) table 81, a X-axis sliding set 82, a the Y-axis sliding set 83, a X-axis moving generator 84, a Y-axis moving generator 85, and a driving assembly 86. This polishing table 81 can slide on two X rods 821 of the X-axis sliding set 82. This X-axis sliding set 82 can slide on two Y rods 831 of the Y-axis sliding set 83. Also, the X-axis moving generator 84 has an X-axis moving link 841 and a first circular disk 842. One end of X-axis moving link 841 is pivoted with the polishing table 81. The other end of the X-axis moving link 841 is pivoted with a first eccentric point 843 of the first circular disk 842. The Y-axis moving generator 85 has a Y-axis moving link 851 and a second circular disk 852. One end of the Y-axis moving link 851 is pivoted with the polishing table 81. The other end of the Y-axis moving link 851 is pivoted with a second eccentric point 853 of the second circular disk 852. Moreover, the driving assembly 86 contains a rotational driving portion 861 (such as a motor), an auxiliary roller 862 and a belt 863 (such as a timing belt). This rotational driving portion 861 drives the belt 863 moving. Accordingly, the first circular disk 842 and the second circular disk 852 are rotated simultaneously. By means of the X-axis moving link 841 and Y-axis moving link 851, a special path 87 is generated on the polishing table 81 (as shown in FIG. 3, similar to a 8-shape, but not an exact double circular path). Therefore, when a user wants to polish (or grind) the end surface of an optical fiber (that has a circular cross-sectional area), one polishing work moves from the lower-right to the upper-left direction (generating many lower-right to upper-left grinding cracks or lines) and the next polishing work should move from the lower-left to the upper-right (generating many lower-left to upper-right grinding cracks or lines). After which, it just repeats again and again. Thus, there will not be any grinding cracks or lines left on this polishing surface. That is, the polished surface is extremely flat. It is suitable to connect with other flat surface without any contacting gap. So, it can meet the high-standard requirement of the optical fiber related products.
However, although the above-mentioned device only needs one driving source, if this belt 863 is too long, it still might be extended a little. Please note that the belt 863 propels the first circular disk 842 and the second circular disk 852. Further, it propels the X-axis moving link 841 and Y-axis moving link 851 as well. If this belt is too loose, it will cause some discrepancies or errors during operation. It cannot be precisely controlled. Besides, the entire system and controlling method become more complicated. So, it cannot produce the exact double circular path nor generate a constant-speed circular movement.