1.  Field of the Invention
The present invention relates to a travel bag and more particularly, to a lightweight, durable, impact resistant travel bag. 
2.  Description of the Related Art
FIG.  1 shows a conventional travel bag.  This structure of travel bag comprises a body 10, which comprises a rectangular plastic open frame 11 equipped with a retractable handle 13 and wheels 12, a cloth covering 14 wrapping the body 10, a cover 15 hinged to the cloth covering 14, and a zipper 16 fastened to the cloth covering 14 and the cover 15 for opening/closing the cover 15. 
This structure of travel bag has drawbacks as follows:
1.  The rectangular plastic open frame 11 is not collapsible and requires much storage space.  In factory, much storage space shall be spared for inventory control. 
2.  The rectangular plastic open frame 11 has only the four peripheral sides to resist impact, and the corner area around the open back side tends to be deformed or damaged accidentally, i.e., the travel bag has low impact resisting power. 
3.  The cloth covering 14 gives little appearance variation to attract consumers.