Patent Publication Number: US-2007108331-A1

Title: Tape measure

Description:
BACKGROUND OF INVENTION  
      1. Field of Invention  
      The present invention relates to a tape measure and, more particularly, to a tape measure capable of automatic braking.  
      2. Related Prior Art  
      Disclosed in Taiwanese Patent M271150 is a restraining device for a tape measure. The tape measure includes a shell defining a slit. A tape is installed in the shell. An end of the tape is inserted from the slit. A switch is installed on the shell corresponding to the slit of the shell. The switch includes a pivotal portion formed at an end near the slit. An abutment element is movably installed on the shell near the slit and connected to the pivotal portion of the switch. The switch is movable on the shell between a restraining position where the abutment element abuts the tape and a releasing position where the abutment element releases.  
      In use, the tape is pulled from the shell when the switch is located in the releasing position. When a desired length of the tape is pulled from the shell, the switch is moved to the restraining position. The switch is frequently moved between the restraining and releasing positions, and this is inconvenient.  
      The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.  
     SUMMARY OF INVENTION  
      According to the present invention, a tape measure includes a shell, a tape and a restraining device. The shell defines a slit and an opening. The tape can automatically be reeled in after it is pulled from the shell through the slit and released. The restraining device is installed in the shell for restraining the tape when a desired length of the tape is pulled from the shell and released. The restraining device includes a trigger exposed from the opening so that the trigger is operable in order to set the tape free.  
      The primary advantage of the tape measure according to the present invention is the convenience in automatically retaining the tape at any desired length because of the use of the restraining device.  
      Other advantages and features of the present invention will become apparent from the following description referring to the drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      The present invention will be described through detailed illustration of two embodiments referring to the drawings.  
       FIG. 1  is a perspective view of a tape measure according to the first embodiment of the present invention.  
       FIG. 2  is an exploded view of the tape measure shown in  FIG. 1 .  
       FIG. 3  is a cross-sectional view of the tape measure taken along a line  3 - 3  in  FIG. 1 .  
       FIG. 4  is a cross-sectional view of the tape measure taken in another position than shown in  FIG. 3 .  
       FIG. 5  is a cross-sectional view of the tape measure taken in another position than shown in  FIG. 4 .  
       FIG. 6  is a cross-sectional view of the tape measure taken in another position than shown in  FIG. 5 .  
       FIG. 7  is a cross-sectional view of a tape measure according to a second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
      Referring to  FIG. 1 , there is shown a tape measure according to a first embodiment of the present invention. The tape measure includes a shell consisting of a first half  10  and a second half  20 , a tape reeled in the shell and a restraining device  40  for automatically allowing the tape  30  to be pulled from the shell and for automatically restraining the tape when the tape is released.  
      Referring to  FIG. 2 , the first half  10  includes a cutout  11  defined therein, a cutout  12  defined therein, a rod  13  formed on a side, a tube  14  formed on the side and two ribs  17  formed on the side. The tube  14  includes a thread formed on an internal side.  
      Similarly, the second half  20  includes a cutout  21  defined therein, a cutout  22  defined therein, a rod  23  formed on a side, a tube  24  formed on the side and two ribs  27  formed on the side. Unlike the first half  10 , the second half  20  includes a restraint  26  formed on the side. An elastic element  25  is installed on the side of the first half  10 . The elastic element  25  is preferably a leaf spring.  
      The first half  10  is joined to the second half  20 . The cutouts  11  and  21  together become a slit for the tape  30 . The cutouts  12  and  22  together become an opening for the restraining device  40 . The rods  13  and  23  together become a shaft for the restraining device  40 . The tubes  14  and  24  together become a cylinder for receiving a fastener for fastening the first half  10  to the second half  20 . The fastener is in the form of a threaded bolt for engagement with the thread formed on the internal side of the tube  14 . The ribs  17  and  27  together become two anvils. The restraint  26  and the anvils together define a channel that gets smaller in a direction away from the slit (see  FIGS. 3 through 6 ).  
      The restraining device  40  includes a trigger  41  exposed from the opening, a tunnel  47  defined in the trigger  41  for receiving the shaft, a ridge  42  formed on a side, an extensive portion  43  extended from an end of the trigger  41  and a connective portion  44  formed at an end of the extensive portion  43 . There is a frame  46  made of a metal rod. The frame  46  includes a section inserted in a tunnel  441  defined in the connective portion  44  and an opposite section for supporting a roller  45 . The roller  45  is made of a frictional material so that there can be adequate friction it and the tape  30 . The trigger  41  includes a skid-proof surface for contact with a user&#39;s finger.  
      Referring to  FIG. 3 , the restraining device  40  can be pivoted on the shaft. The ridge  42  is located against the elastic element  25  so that the restraining device  40  is biased by the elastic element  25 . The roller  45  is pressed against the restraint  26  so that the rotation of the former is prevented by the latter. The roller  45  is pushed towards the anvils so that the tape  30  is pinched by and between the roller  45  and the anvils.  
      Referring to  FIG. 4 , the tape  30  is pulled from the shell so that the roller  45  is moved from the restraint  26  by the tape  30 . The roller  45  is free to rotate in order to allow further pulling of the tape  30 . The elastic element  25  is loaded.  
      Referring to  FIG. 5 , the tape  30  is released since a desired length thereof has been pulled from the shell. The tape  30  is automatically reeled in. However, as soon as the automatic reeling in of the tape  30  begins, the roller  45  is moved back to the restraint  26  by the elastic element  25 . The rotation of the roller  45  is prevented by the restraint  26 . The tape  30  is pinched between the roller  45  and the anvils so that further reeling in of the tape  30  is prevented.  
      Referring to  FIG. 6 , the trigger  41  is operated in order to move the roller  45  from the restraint  26  and the anvil. The rotation of the roller  45  is allowed so that the reeling in of the tape  30  is allowed.  
      Referring to  FIG. 7 , there is shown a tape measure according to a second embodiment of the present invention like the first embodiment except including a helical spring  28  compressed the shell and the extensive portion instead of the leaf spring  25  provided between the shell and the ridge  42 .  
      An advantage of the tape measure is the convenience in automatically retaining the tape at any desired length for using the restraining device. Another advantage is ease and a low cost in its fabrication.  
      The present invention has been described via the illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Hence, the embodiments shall not limit the scope of the present invention defined in the claims.