Abstract:
An improved structure tape rule in which the blade spool has space at one side of one-piece construction for containing the coiled spring, enabling the blade spool to accommodate the winding of a ruler blade that is approximately two to three times longer than a blade spool in a same diameter sized spatial area and, furthermore, the rewinding of the ruler blade is impelled by spring torque to thereby enhance tape ruler utility and performance.

Description:
BACKGROUND OF THE INVENTION 
   1) Field of the Invention 
   The invention herein relates to an improved structure tape rule, specifically an original structural arrangement in which the blade spool has space at one side of one-piece construction for containing the coiled spring, enabling the blade spool to accommodate the winding of a ruler blade that is approximately two to three times longer than a blade spool in a same diameter size spatial area and, furthermore, the rewinding of the ruler blade is impelled by spring torque to thereby enhance tape ruler utility and performance. 
   2) Description of the Prior Art 
   A conventional tape rule utilizing an internal blade spool consists of a concentric spring at the center and a ruler blade wound around the exterior, a hook riveted to the front end of the ruler blade, and a center shaft projecting from the inner side of a left case half for inserting the center section of the spring in the blade spool; screws are respectively inserted through mounting holes in the right case half on the other side and fastened to the center shaft and mounting posts of the left case half to thereby assemble the said tape rule. Given the structure of the conventional tape rule, since there is a concentric spring coiled in the said blade spool, the said spring occupies space at the center of the blade spool and the remaining space can only be used for winding the tape ruler blade, a conventional tape ruler blade has a length of approximately five meters; furthermore, extending the length of the tape ruler blade requires an increase in the diameter of the blade spool and, at the same time, when the tape ruler blade is utilized for measurements and pulled out longer distances, the rewinding torque of the spring must be considered in that additional space will be needed to fit a stronger spring; however, to meet ergonomic concerns, since the maximum dimensions of the tape rule housing is limited to what the average hand is capable of grasping, increasing the diameter of the blade spool is difficult. As a result, to facilitate tape rule usage, the applicant of the invention herein conducted extensive research and development based on many years of specialized production experience to further enhance the practical value of the invention herein which following repeated testing and refinement culminated in the improved tape rule structure of the present invention. 
   SUMMARY OF THE INVENTION 
   Therefore, the primary objective of the invention herein is to provide an improved structure tape rule, specifically an original structural arrangement in which the blade spool has space at one side of one-piece construction for containing the coiled spring, enabling the blade spool to accommodate the winding of a ruler blade that is approximately two to three times longer than a blade spool in a same diameter size spatial area and, furthermore, the rewinding of the ruler blade is impelled by spring torque to thereby enhance tape ruler utility and performance. 
   To enable the examination committee a further understanding of the structural features, innovative content, and advantages of the invention herein, the brief description of the drawings below are accompanied by the detailed description of the embodiments 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric drawing of the invention herein. 
       FIG. 2  is an exploded drawing of the invention herein. 
       FIG. 3  is an exploded drawing of the invention herein. 
       FIG. 4  is an exploded drawing of the blade spool  5  of the invention herein. 
       FIG. 5  is an exploded drawing the blade spool  5  of the invention herein. 
       FIG. 6  is a cross-sectional drawing the invention herein, as viewed from the perspective line A—A in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 ,  FIG. 2 , and  FIG. 3 , the improved structure tape rule  10  of the invention herein is comprised of a left case half  2 , a right case half  3 , a blade lock  4 , and a blade spool  5 , wherein: 
   The left case half  2  is of one-piece plastic construction, a plurality of threaded holes  21  are disposed along the interior periphery of the said left case half  2  and, furthermore, a shaft tube  22  protrudes from the center of the interior, and a round hole  23  is disposed through the center of the shaft tube  22 . 
   The right case half  3  is of one-piece plastic construction, a plurality of mounting holes  31  are disposed along the interior periphery of the said left case half  2  and, furthermore, a metal center shaft  32  is situated inward from the center of the left case half  2 , the metal center shaft  32  having a circular rod-shaped, horizontally oriented slot  321 . 
   The blade lock  4  is fitted into the front edges of the left case half  2  and the right case half  3 . 
   The blade spool  5 , as indicated in  FIG. 4  and  FIG. 5 , is of one-piece plastic construction and has flanges  51  along the center and one side, a plurality of catch slots  52  and semi-circular, arcuate mounting slots  53  along the inner edge at the outer side of one flange  51 , two symmetrical blade mounting slots  54  and  55  respectively disposed on a blade retaining hub  511  between the said two flanges  51 , and a plurality of catch slots  561  along the outer circumference of a tube-shaped reel  56  at the other side of the said blade spool  5 , the said reel  56  having a rectangular hole  57  and, furthermore, two symmetrical mounting slots  58  and  59  respectively formed at the front and rear edges of the rectangular hole  57 . 
   Additionally, a side cover plate  6  of one-piece plastic construction in the form of a circular plate that has a round shaft hole  61  through its center and, furthermore, a plurality of lock tabs  62  protruding along the outer circumference, with the said side cover plate  6  also having plurality of semicircular mounting tabs  63  protruding along its outer circumference; the said side cover plate  6  lock tabs  62  and mounting tabs  63  are snap-fitted into the catch slots  52  and the mounting slots  53  at one side of the blade spool  5 , thereby providing for attachment to the blade spool  5 . 
   Moreover, a spring cover plate  7  of one-piece plastic construction in the form of a circular plate that has a round shaft hole  71  through its center and, furthermore, a plurality of lock tabs  72  protruding along the outer circumference; the said spring cover plate  7  lock tabs  72  are snap-fitted into the catch slots  561  at the other side of the blade spool  5 , and thereby attached to the blade spool  5 . 
   Referring to  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5 , and  FIG. 6 , one extremity of the ruler blade  8  is inserted and fixed in the blade spool  5  blade mounting slot  55  and then wound onto the blade retaining hub  511  along one side of the blade spool  5  between the two flanges  51 ; one end of the said spring  73  is inserted and fixed in the blade spool  5  mounting slot  59  and then coiled within the reel  56 , the center end in the coiled concentric said spring  73  is inserted and fixed in the center shaft  32  horizontally oriented slot  321 ; the left case half  2  and the right case half  3  are placed together, inserting the said center shaft  32  into the shaft tube  22 , and a mounting screw  24  fastens them, a plurality of mounting screws  33  are then inserted into the right case half  3  mounting holes  31  and fastened in the left case half  2  threaded holes  21 , the conjoinment completing the tape rule structure of the present invention. 
   In the structural component assembly of the invention herein, the blade spool  5  has space at one side of one-piece construction for containing the coiled spring  73 , enabling the outer housing of the tape rule to have dimensions within a range of manual grasping and thus comply with ergonomic considerations, and the said blade spool  5  is capable of holding additional ruler blade length, increasing capacity such that it is approximately two to three times longer than that of a conventional tape rule, the improved structure herein thereby effectively enhancing tape rule utility and performance. 
   The invention herein can be assembled such that the blade spool  5  rotates 180 degrees, while the left case half  2  and the right case half  3  are structurally re-positioned with corresponding symmetry such that the original right-hand grasped tape rule structure is converted into a left-hand grasped tape rule structure to thereby enhance product assembly convenience and precision, providing even greater manufacturing practical value. 
   In summation of the foregoing section, since the invention herein remedies the shortcomings of the conventional product and in terms of utility is a leading innovation among products in the same category and, furthermore, capable of realizing even greater practical performance, the disclosed structure thereof is ensured to be capable of achieving the claimed objectives and is submitted for review and the granting of the commensurate patent rights.