Abstract:
A rotational tape retracting and releasing structure for tape measure is provided which has less rotational wearing and trouble, increased reliability of cooperative rotation, and an easier assembling and disassembling structure. The subject structure for tape measure is characterized in that: a set of planetary gears can be firmly kept inside a gear box and then presented from departing out of the housing, and a sub-rotary disc axis member and a take-up drive can be rotated together.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a rotational tape retracting and releasing structure for tape measure, it takes up the tape quickly by using a planetary gear mechanism.  
         [0003]     2. Description of the Prior Art  
         [0004]     A conventional take up structure for tape measure is shown in  FIG. 1 , it comprises a front housing  10 , a rear housing  11 , a handle  12  and a capping plate  13 . Wherein, the handle  12  and capping plate  13  are formed in one piece, the capping plate  13  is rotated between front housing  10  and rear housing  11 , tape  14  is wound onto the surface of capping plate  13 . The tap  14  is retracted or released when the handle  12  is rotated.  
         [0005]     Such a conventional tape measure has the following disadvantages: 
    (1) Because of the structure described above, it is necessary to intentionally leave a gap between the capping plate and the handle, which would result in anyone of frictional wear; breakage in a narrow gap thereof; and mechanical trouble due to penetration of soil or dust in a broad gap thereof.     (2) Because of the structure described above, the rotation of tape drum is controlled by rotation of handle, while the rotation of handle is operated by hand. It then cannot have a quick measure.     (3) Because of the structure described above, if the handle is quickly rotated by hand, it is easier to cause harm to the user.    
 
         [0009]     The applicant has been authorized by the patentee of U.S. Pat. No. 5,718,056 to use, manufacture and sell the product of the patent, and, after many years of producing, he find the mechanism of said patent has disadvantage that the gears would be separated and released from the rotational mechanism especially when the handle is rotated fast.  
       SUMMARY OF THE INVENTION  
       [0010]     Then, it is an object of the present invention to solve the problems described above of the conventional tape measure and to provide a novel tape measure.  
         [0011]     An another object of the present invention is to provide a rotational tape retracting and releasing structure for tape measure, which includes: a main rotary disc axis member provided with a take-up handle fitted on an outside surface and a first short axis integrally formed in a center of an inside surface thereof and rotatably inserted into a layer bearing hole formed on an outer surface of the inward collar portion of the bearing member; and a sub-rotary disc axis member provided with a bearing hole in a center thereof and arranged opposingly to the main rotary disc axis member in the inward collar portion to fit the first short axis in the bearing hole, the sub-rotary disc axis member being rotatably fixed to the main rotary disc axis member by means of an anti-departing plate by screwing a third screw to an end surface of the first short axis, thereby forming gear box space surrounded by the main and sub-rotary disc axis, as well as the inward collar portion.  
         [0012]     Because of the above-mentioned structure of the present invention, the sub-rotary disc axis member, which also functions as a conventional capping plate when the take-up handle is rotated, and the take-up drum is rotated together at a doubled velocity by means of the planetary gears. Accordingly, it is not necessary to intentionally leave a gap between the sub-rotary disc axis member and the take-up drum, such an improved structure of the present invention can prevent problems or rotational wearing caused by the penetration of soil or dust in the gap.  
         [0013]     According to the rotational tape retracting and releasing structure for tape measure of the present invention, the take-up drum is rotated at a doubled velocity of the handle. Then the tape can be smoothly taken-up more quickly, this is another object of the present application.  
         [0014]     According to the rotational tape retracting and releasing structure for tape measure of the present invention, the handle is rotated much more slowly than the take-up drum. It can prevent a damage and troublesome to people due to the rotation of handle in high velocity.  
         [0015]     According to the rotational tape retracting and releasing structure for tape measure of the present invention, as the sub-rotary disc axis member and the take-up drum are connected by fitting the lateral convex portions and the oblong concave portion, complete cooperation of rotation thereof can be achieved by the above-mentioned structure. In addition, as the gear system is assembled as unit and the unit thus assembled is kept firmly inside a gear box by means of an anti-departing plate screwed onto the shafts of planetary gears, then the planetary gears can be prevented from departing out of the housing of tape measure, when the handle is rotated fast. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The above object and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:  
         [0017]      FIG. 1  is a cross-sectional view showing the rotational structure of conventional tape measure;  
         [0018]      FIG. 2  is a perspective view showing the embodiment of a tape measure having the structure of present invention;  
         [0019]      FIG. 3  is an exploded view showing the parts of present invention;  
         [0020]      FIG. 4  is a plane view showing an arrangement of the gears in a bearing member of present invention;  
         [0021]      FIG. 5  is a perspective view showing the structure between the take-up drum and a sub-rotary disc axis member of present invention;  
         [0022]      FIG. 6  is a cross-sectional view showing the structure of present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]     The structure of the conventional tape measure shown in  FIG. 1 , together with its disadvantages and stated above, it is not necessary to repeat here.  
         [0024]     In the example shown in  FIG. 2  and  FIG. 3 , it is shown that the present invention comprises:  
         [0025]     a front housing  2  and rear housing  3  with a ring-like grip portion  20 ,  30  are made of rigid plastics;  
         [0026]     a rotational mechanism  4  together with tape  5  are put inside the housing space between the front housing  2  and rear housing  3 , after the front housing  2  and rear housing  3  are combined with each other, they are fixed buy means of screws.  
         [0027]     At the central portion of front housing  2 , there is a bearing supporting hole  21  with screw holes  211 ,  212 ,  213  on its periphery, such that a ring-like bearing member  40  can be fixed onto the front housing  2  by means of screws  411 ,  412 ,  413  being screwed into the fixing holes  401 ,  402   403  formed on the outer extended fitting flange  41  of ring-like bearing member  40 .  
         [0028]     Please refer to  FIG. 3 , it is shown that on the inner surface of ring-like bearing member  40 , a gear annulus  43  is formed, and a plurality of planetary gears  431 ,  432 ,  433 ,  434  are fitted with gear annulus  43  by means of pin-bearing axes  441 ,  442 ,  443 ,  444  integrally formed on a side surface of the main rotary disc axis member  44 . On the another side surface of the main rotary disc axis member  44 , a handle  45  is integrally formed. If the handle  45  is rotated, each of the planetary gears  431 ,  432 ,  433 ,  434  then rotates on the said gear annulus  43 . At the central portion of the main rotary disc axis member  44 , there is a long axis  440 . Thus, the sub-rotary disc axis member  46  is rotatably fixed to the main rotary disc axis member  44  by mounting it onto the long axis  440  and fixing it by screw  480  from the outside of rear housing  31  (as shown in  FIG. 6 ). One side surface of sub-rotary disc axis member  46  is formed of a sun gear  461 . The planetary gears  431 ,  432 ,  433 ,  434  are intermeshed with the gear annulus  43  and the sun gear  461  to rotate. There is also a fixing hole  4410  ( 4420 ,  4430 ,  4440 ) formed on the top end of the each pin-bearing axes  441 ,  442 ,  443 ,  444 . An anti-departing plate  430  having screw hole  4301 ,  4302 ,  4303 ,  4304  is then fixed onto the top end of the pin-bearing axes  441 ,  442 ,  443 ,  444  by screws  4311 ,  4312 ,  4313 .  4314  to keep the planetary gears  431 ,  432 ,  433 ,  434  inside the ring-like bearing member  40  from being departed out of the ring-like bearing member  40 , when it is rotated.  
         [0029]     Please refer to  FIG. 3  again and further to  FIG. 5 , on the another side surface of sub-rotary disc axis member  46 , a plurality of separated lateral convex portions  462 ,  463  are formed across a center longitudinal axis of the main rotary disc axis member  44 , while an oblong convex portion  471 ,  472  is formed on a side surface of the take-up drum  47  opposingly to the sub-rotary disc axis member  46 . The take-up drum  47  has a pillar-shaped furrow  473 , while the sub-rotary disc axis member  46  has a catch pin  464  mounted on a side surface close to a periphery thereof to allocate in the said pillar-shaped furrow  473 . Such that the take-up drum  47  will rotate with sub-rotary disc axis member  44 . There is a pin  474  for one end of tape  5  to be fixed onto and then enable tape  5  to be wound onto the side surface of take-up drum  47 . And a central hole  460 ,  470  is formed at the central part of take-up drum  47  and sub-rotary disc axis member  46  respectively for the long axis  440  to pass through. Between said sub-rotary disc axis member  46  and said take-up drum  47 , there is a spring  475 .  
         [0030]     Please refer to  FIG. 3 ,  FIG. 4  and  FIG. 5  again, in taking up the tape  5 , rotate the handle  45 , the main rotary disc axis member  44  then rotates accordingly. At this time, the planetary gears  431 ,  432 ,  433 ,  434  then rotate on the inner surface of gear annulus  43  of ring-like bearing member  40 , the sun gear  461  and the take-up drum  47  then rotate simultaneously so as to take up the tape  5  and make the tape  5  be wound onto the take-up drum  47 . When the handle  45  is rotated, since each of the planetary gears  431 ,  432 ,  433 ,  434  rotates by using the pin-bearing axes  441 ,  442 ,  443 ,  444  as its rotation shaft respectively. The rotational velocity of take-up drum  47  is higher than the rotational velocity of handle  45 , due to the radius of gear annulus  43  is much larger than the radius of sun gear  461 , and the rotational velocity of sun gear  461  is higher than that of gear annulus  43 .  
         [0031]     Because the anti-departing plate  430  is fixed outo the top end of the pin-bearing axes  441 ,  442 ,  443 ,  444  to keep the planetary gears  431 ,  432 ,  433 ,  434  inside the ring-like bearing member  40  from being departed out of the ring-like bearing member  40  when it is rotated, and the axis  440  formed at the central part of the ring-like bearing member  40  is long enough to pass through the central holes  460 ,  470  formed at the central portions of take-up drum  47  and sub-rotary disc axis member  46 , then fixed to a screw  480  extended inside the rear housing  3  from the outside of rear housing  3 . Therefore, the construction of present invention is much stronger than the U.S. Pat. No. 5,718,056 which is authorized to the applicant.  
         [0032]     It is noted that the present invention is not limited to the preferred embodiment described above, and it is apparent that variations and modifications by those skilled in the art can be effected within the spirit and scope of the present invention defined in the appended claims.