Patent Publication Number: US-6905240-B2

Title: Case, strap and timepiece

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a case, a strap and a timepiece combined with the case and the strap. 
   2. Description of the Prior Art 
   An explanation will be given of a conventional case, a conventional strap and a conventional timepiece in reference to the drawings.  FIG. 3  is a sectional view in a state of a timepiece attaching a strap to a case.  FIG. 4  is a sectional view of the case and the strap. 
   A conventional case  5  is provided with a strap attaching portion roof  52  for attaching a strap  6 . The strap attaching portion roof  52  is provided with a strap attaching portion  51  constituting a space for bringing a portion of the strap  6  to a side of a caseback (hereinafter, referred to as ‘bottom side’). Further, the strap attaching portion  51  is opened with a spring rod pin hole  55  for inserting a spring rod  3 . 
   Further, the conventional strap  6  is provided with a spring rod hole  65  for inserting the spring rod  3  in a width direction of the strap. A periphery of the spring rod hole  65  is provided with a strap inserting face  62  for inserting to the strap attaching portion  51 . Further, the strap inserting portion  62  is provided with a stepped difference such that the strap  6  is prevented from rotating when the strap  6  is attached to the case  5 . Further, the strap  6  is provided with a rotation stop tongue  67  which is brought into contact also with a case back  57  to thereby prevent rotation. 
   Further, the conventional timepiece is assembled with the strap  6  and the case  5  by inserting the spring rod  3  into the spring rod hole  65  of the strap  6  and inserting a front end of the spring rod  3  into the spring rod pin hole  55  of the case  5 . 
   The conventional timepiece has a problem in that when the strap attaching portion has stress applied thereto for rotating the strap in a direction of a rear face thereof, a large gap is produced at a portion of coupling the case and the strap, or the strap is rotated. 
   Further, in order to prevent the rotation, there is a method of setting positions of a spring rod pin hole of a case and a spring rod hole of a strap and attaching the case and the strap by a spring rod  3  constituting a connecting member in a shaft-like shape penetrating the case and the strap such that the strap is pressed to attach to the case as much as possible by utilizing elasticity of the strap. However, the method has a problem in that repulsive force produced by pressing the strap to the case is always applied to the spring rod pin hole for holding the shaft-like connecting member of the case shown in  FIG. 4  respectively in a horizontal direction f 1  and a vertical direction f 2  and therefore, the case is deformed by the repulsive force. When the repulsive force is strong, a crack can occur. When the shape of a surrounding of the spring rod pin hole  55  is deformed, the spring rod cannot be held and the strap is detached from the case. 
   SUMMARY OF THE INVENTION 
   According to a timepiece of the invention, in a timepiece including a case formed with a strap attaching portion roof at a strap attaching portion thereof, a strap attached to the case, and a spring rod holding the strap to the case by penetrating the case and the strap, the case includes a roof rear face recessed portion formed by recessing a portion of the roof rear face of the strap attaching portion, the strap includes a rotation stop projection at a rotation stop face of the strap and prevents rotation of the strap by engaging the rotation stop projection and the roof rear face recessed portion. 
   The roof rear face recessed portion is formed at the roof rear face of the strap attaching portion of the case, the rotation stop projection is formed at the rotation stop face of the strap opposed to the recessed portion and the recessed portion and the projected portion are respectively engaged with each other to thereby stop rotation of the strap in view of its structure. 
   A band according to the invention includes a rotation stop face provided with a stepped difference from an outer shape thereof in an inner direction and the rotation stop face includes a rotation stop projection extended in a direction of the outer shape. 
   Further, the band according to the invention further includes a spring rod hole for inserting a connecting member to be attached to other member and the rotation stop projection is disposed upward from the spring rod hole. 
   A case according to the invention is a case including a strap attaching roof for attaching a strap, and a strap attaching portion for inserting the strap to a rear face of the strap attaching roof and the strap attaching portion includes a roof rear face recessed portion for stopping rotation of the strap. 
   Further, a timepiece according to the invention includes the strap, the case, and a connecting member for attaching the strap to the case and prevents rotation of the strap by engaging the rotation stop projection and the roof rear face recessed portion of the case with each other when the strap is assembled to the case. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     A preferred form of the present invention is illustrated in the accompanying drawings in which: 
       FIG. 1  is a partially sectional view showing a state of attaching a strap according to the invention; 
       FIG. 2  is a partially sectional view showing portions of a timepiece case and a strap according to the invention corresponding to the invention; 
       FIG. 3  is a partially sectional view showing a state of attaching a conventional strap; 
       FIG. 4  is a partially sectional view showing portions of a conventional timepiece and a conventional strap corresponding to the invention; and 
       FIG. 5  shows a spring rod of a shaft-like connecting member. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A roof rear face recessed portion  14  is formed at a roof rear face  13  of a strap attaching portion  11  of a timepiece case  1 , a rotation stop projection  24  is formed at a rotation stop face  23  of a strap opposed to the recessed portion, and the recessed portion  13  and projected portion  24  are respectively engaged with each other to thereby prevent rotation of the strap. This structure eliminates the need for attaching the band to press to the timepiece case as much as possible by utilizing elasticity of the strap as a method of reducing danger of rotation and prevents stress from being applied to the spring rod pin hole  55  for holding the spring rod  3  of a shaft-like connecting member of the timepiece case, as shown in  FIG. 4 , in f 1  and f 2  directions which causes with the elapse of time, a surrounding of the spring rod pin hole  55  of the timepiece case  5  to be deformed by delayed fracture by stress applied to the synthetic resin. 
   EXAMPLES 
   A detailed description will be given of an embodiment of the invention in reference to FIG.  1  and FIG.  2 .  FIG. 1  is a sectional view showing a state of attaching a strap according to the invention and  FIG. 2  is a sectional view of a timepiece case and a strap according to the invention. 
   According to a specific embodiment, there is formed a roof rear face recessed portion  14  at a roof rear face  13  of a strap attaching portion roof  12  constituting a strap attaching portion  11  of a timepiece case  1  of synthetic resin (generally, ABS resin). The depth of the recessed portion  14  is set to about 2 mm. A strap  2  has a case attaching portion comprised of a rotation stop face  23  on a front surface thereof. The rotation stop face  23  has a stepped shape which defines a rotation strap projection  24  to be engaged with the roof rear face recessed portion  14 . The strap  2  is made of polyurethane constituting an elastic material attached to the timepiece case  1 . 
   The timepiece case  1  and the strap  2  constituted in this way are attached by inserting a connecting member into a spring rod hole  25  of the strap  2  and spring rod pin holes  15  of the timepiece case  1 . The connecting member is preferably a spring rod  3  as shown in FIG.  5 . 
   According to the strap attached in this way, a rotation stop tongue  27  of the strap  2  is brought into contact with a case back  17  of the timepiece case  1  to thereby assist in preventing rotation of the strap  2  and at the same time, there can be resolved the conventional problem that when applied with a stress of rotating the strap  6  in a lower direction (see FIGS.  3 - 4 ), the rotation stop face  63  of the strap  6  is elastically deformed and slid on the roof rear face  53  of the timepiece case  5  to detach from the roof rear face  53 , by engaging the roof rear face recessed portion  14  of the timepiece case  1  and the rotation stop projection  24  of the strap  2 . 
   According to the invention, rotation of the strap which is easy to rotate, can firmly be prevented and the gap produced at the portion of coupling the timepiece case and strap can be made to be very small. Further, there can be resolved stresses in the horizontal and the vertical directions generated at the spring rod pin hole for holding the shaft-like connecting member. Thereby, the spring rod pin hole can be prevented from being deformed and the strap can be prevented from being detached. Particularly, although according to a timepiece case using synthetic resin, there is also a case of causing delayed fracture by stress, by resolving the stress, the delayed fracture of the case can also be prevented.