Tape rule with a tape of enhanced stiffness

A tape rule with a tape of enhanced stiffness comprising:

• A tape rule housing (1) having a peg provided at the center of said housing thereof;
• a rewinding core spring for rewinding a tape into said housing, being spirally accommodated therein with its one end conjoined to said peg, while the other end fixed to a protective ring;
• and
• said tape having a series of graduations on the surface thereof being spirally wound and accommodated in said housing with its one end secured to said protective ring at the position facing against the end of said core spring (2) fixed to said protective ring, the other end being remained free for pulling;
• wherein said tape is 27 mm wide, 0.11 mm thick and cambered its both ends at a height of 6.75 mm so as to ensure its stiffness when being pulled out 10.5 feet out said housing wherein said rewinding core spring is 22 mm wide, 0.125 mm thick and 4500 mm long and the total diameter of said rewinding core spring when in spirally wound state is 14 mm and wherein the cambered height from either end of an erected V cross section formed of first and two second surfaces of the transverse cross section of the tape to the tangential plane to the bottom lowest point of the cambered surface of the tape is 6.75 mm, and said first surface being approximately perpendicular to a portion of said second surface;
• and
• wherein angle of curvature of said first surface is 82° and the length of said first surface is 13.12 mm, the radius of curvature of said first surface is 10 mm, the length of two second surface is 6.5 mm each and wherein the total length of said first and second surfaces is 26.12 mm.