Abstract:
A battery holding structure for an electronic timepiece has a battery frame having an opening for receiving a battery. The battery frame has a plurality of fittings each having a tapered overhang extending toward the opening for holding the battery in the opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national stage application of copending International Application Ser. No. PCT/JP01/02373, filed Mar. 23, 2001 claiming a priority date of Apr. 6, 2000, and published in a non-English language. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to battery holding structures and, more specifically, to a battery holding structure for holding a battery in an electronic timepiece. 
     2. Background Information 
     Conventionally, in an electronic timepiece of a digital display type or an analog display type, a battery is used as a drive source. Conventionally, as a method of attaching a battery to a timepiece main body, the battery is integrated to the timepiece main body and thereafter, the battery is held by using a separate member for holding the battery such as a battery holder. 
     FIG.  6  and  FIG. 7  show a battery holding structure of a conventional electronic timepiece using a battery holder.  FIG. 6  is a plane view of a periphery of a battery holding structure, and  FIG. 7  is a front sectional view along a line D—D in FIG.  6  and the same notations are attached to the same portions. 
     In FIG.  6  and  FIG. 7 , numeral  401  designates a battery, numeral  402  designates a battery frame made of resin having an opening portion having a diameter slightly larger than that of the battery  401 , numeral  403  designates a battery holder made of a metal constituted by a member separate from that of the battery frame  402 , numeral  404  designates an eaves portion integrally formed with the battery frame  402 , and numeral  405  designates a positive electrode terminal. When the battery  401  is attached to inside of the battery frame  402 , the battery  401  is attached to inside the battery frame  402 , the battery  401  is contained in the opening portion of the battery frame  402  to dispose on a lower side of the eaves portion  404  and, thereafter, the battery holder  403  is attached to the battery frame  402  from an upper side of the battery  401 . By this construction, a positional shift of the battery  401  in a plane direction is prevented by the battery frame  402 . Furthermore, since the battery  401  is sandwiched by the battery frame  402 , the battery holder  403  and teh eaves portion  404 , a positional shift in a sectional direction and detachment of the battery  401  are prevented. Further, the battery  401  is also held in a state of being brought into electrical contact with the positive electrode terminal  405  and a negative electrode terminal (not illustrated). 
     As described above, by using the battery holder  403 , the battery  401  can be held. 
     However, according to the above-described conventional battery holding structure, in order to prevent the battery  401  from moving in the sectional direction, the battery holder  403  must be a part separate from the battery frame  402 , thereby increasing number of integrating steps and resulting in a complicated and expensive battery holding structure. Further, another problem is that a thickness of the electronic timepiece is increased since the battery holder  403  is arranged to overlap the battery  401 . 
     It is an object of the invention to provide a battery holding structure of an electronic timepiece which is inexpensive to manufacture and has a simple constitution. Further, it is another object of the invention to provide a battery holding structure which allows the thickness of an electronic timepiece to be reduced. Further, it is another object of the invention to provide a battery holding structure capable of holding a battery firmly such that the battery is not positionally shifted even when an electronic timepiece is dropped. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a battery holding structure as described below which achieves foregoing aspects. 
     That is, according to an aspect of the invention, there is provided a battery holding structure of an electronic timepiece characterized in comprising a battery frame having an opening portion for holding a battery, wherein the battery frame is provided with engaging portions projected to a side of the opening portion and having eaves portions provided with tapers. The battery is inserted into the opening portion and is held by the eaves portions of the engaging portions. 
     Here, there may be constructed a constitution in which a plurality of the engaging portions are provided and the eaves portions of the engaging portions are provided with the tapers in shapes by which when the battery is attached, the battery is brought into contact with narrow width portions of the eaves portions and thereafter brought into contact with wide width portions thereof. 
     Further, there may be constructed a constitution in which the engaging portions are constituted by the eaves portions and arm portions having an elasticity for attaching the eaves portions to the battery frame. 
     Further, there may be constructed a constitution in which the battery frame and the engaging portions are integrally molded by an insulating resin. 
     Furthermore, there may be constructed a constitution in which the eaves portions are integrally formed with projected portions which are brought into contact with a case back in a state of being mounted with the case back. 
     Further, there may be constructed a constitution in which at least portions of the projected portions are constituted to project to the side of the opening portion more than inner wall faces of the engaging portions and are brought into contact with the case back at positions projected to the side of the opening portion more than the inner wall faces. 
     Further, the battery may be a button battery. 
     Further, the electronic timepiece may be an electronic wristwatch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plane view showing a specific example of a battery holding structure of an electronic timepiece according to the invention. 
         FIG. 2  is a partial front sectional view showing the specific example of the battery holding structure of the electronic timepiece according to the invention. 
         FIG. 3  is a front sectional view showing a mode of use of the specific example of the battery holding structure of the electronic timepiece according to the invention. 
         FIG. 4  is a plane view showing another specific example of a battery holding structure of an electronic timepiece according to the invention. 
         FIG. 5  is a partial front sectional view showing the other specific example of the battery holding structure of the electronic timepiece according to the invention. 
         FIG. 6  is a plane view showing a battery holding structure of a conventional electronic timepiece. 
         FIG. 7  is a partial front sectional view showing the battery holding structure of the conventional electronic timepiece. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A detailed explanation will be given of specific examples of battery holding structures of an electronic timepiece according to the invention with reference to the drawings as follows. 
       FIG. 1  is a plane view showing a specific example of a battery holding structure of an electronic timepiece according to the invention, showing an example of an electronic wristwatch. Further,  FIG. 2  is a front sectional view taken along a line A—A of FIG.  1 . Further, in FIG.  1  and  FIG. 2 , there is shown a state of holding a battery in a battery frame and the same portions are attached with the same notations. 
     In FIG.  1  and  FIG. 2 , numeral  101  designates a button battery which is a kind of battery, numeral  102  designates a battery frame made of insulating resin having an openign portion  113  having a diameter slightly larger than that of the battery  101 , numerals  103  through  109  designate a plurality of fittings or engaging portions constituted by molding insulating resin integrally with the battery frame  102 , numeral  110  designates a positive electrode terminal, numeral  111  designates a negative electrode terminal having elasticity urged to project from a hole  112  formed at a bottom portion of the battery frame  102  and numeral  114  designates a winding stem. 
     The engaging portions  103  through  109  have overhang or eave portions  103   a  through  109   a , respectively, projected to sides of the opening portion  113  for preventing a positional shift in a sectional direction or detachment of the battery  101 , and arm portions  103   b  through  109   b , respectively connecting the eave portions  103   a  through  109   a  to the battery frame  102  and having elasticity for restricting a positional shift of the battery  101  in a plane direction. 
     The eaves portion  105   a  through  108   a  of the plurality of engaging portions  105  through  108 , are provided with tapers in shapes by which when the battery  101  is attached, the battery  101  is brought into contact with narrow width portions  105   c  through  108   c  of the eaves portion  105   a  through  108   a  and thereafter brought into contact with wide width portions  105   d  through  108   d  thereof. 
     Further, the eaves portion  109   a  of the engaging portion  109  is not provided with taper. Further, although the eaves portion  103   a  and  104   a  of the engaging portions  103  and  104  are provided with tapers and respectively formed with narrow width portions  103   c  and  104   c  and wide width portions  103   d  and  104   d , at an initial stage of attaching the battery  101 , one end portion of the battery  101  is inserted into lower sides of the eaves portion  103   a  and  104   a  and therefore, it is not necessarily needed to provide the tapers to the eaves portions  103   a  and  104   a.    
       FIG. 3  is a front sectional view showing a mode of use when the battery  101  is attached to inside of the battery frame  102 , showing a sectional view in correspondence with a B—B section of the battery frame  102  in FIG.  1 . 
     A detailed explanation will be given of the specific example in reference to FIG.  1  through  FIG. 3  as follows. 
     When the battery  101  is attached to inside of the battery frame  102 , first, in a previously determined direction of inserting the battery  101 , that is, along an arrow mark C direction, one end edge portion of the battery  101  is inserted into an interval between the negative electrode terminal  111  and the eaves portion  103   a  and  104   a  of the engaging portions  103  and  104  and is brought into contact with an inner peripheral edge of the battery frame  102  (refer to FIG.  3 ). 
     Under the state, the battery  101  is depressed from above such that other end edge portion of the battery  101  is disposed on a lower side of the eaves portion  109   a  of the engaging portion  109 . The battery  101  is successively brought into contact with the narrow width portions  105   c  through  108   c  of the eaves portions  105   a  through  108   a  of the engaging portions  105  through  108  and the wide width portions  105   d  through  108   d , when the battery  101  is further depressed, as shown by broken lines of  FIG. 2 , at inside of the battery frame  102 , the battery  101  is brought to lower sides of the eaves portions  103   a  through  109   a  of the engaging portions  103  through  109  and the battery  101  is contained and held at inside of the opening portion  113  of the battery frame  102 . 
     At this occasion, since the eaves portions  105   a  through  108   a  are provided with the tapers, when the battery  101  is contained and held at inside of the opening portion  113  as described above, by successively bringing a peripheral edge of the battery  101  into contact with the eaves portions  105   a  through  108   a , as shown by bold lines of  FIG. 2 , the arm portions  105   b  through  108   b  having elasticity are successively bent to expand and the eaves portions  105   a  through  108   a  are also expanded. Thereby, the battery  101  can easily be contained at a holding portion thereof of FIG.  1  and FIG.  2 . The battery  101  is contained and held at inside of the opening portion  113  of the battery frame  102  and a positive electrode and a negative electrode of the battery  101  are respectively held in a state of being brought into electrical contact with the positive electrode terminal  110  and the negative electrode terminal  111 . 
     When the battery  101  is held at inside of the opening portion  113  of the battery frame  102  in this way, the battery  101  is prevented from being positionally shifted in the plane direction by a peripheral wall portion of the battery frame  102  and the arm portions  103   b  through  109   b  of the engaging portions  103  through  109  and prevented from being positionally shifted in the sectional direction or detached by the eaves portions  103   a  through  109   a . Further, when the battery  101  is interchanged, the battery  101  can easily be removed by using a tool of tweezers or the like. 
     As has been described above, the battery holding structure of an electronic timepiece according to the specific example of the invention is characterized particularly in having the battery frame  102  having the opening portion  113  for inserting and holding the battery  101  such as the button battery, in which the battery frame  102  is formed with the engaging portions  105  through  108  having the eaves portions  105   a  through  108   a  projected to the side of the opening portion  113  and provided with the tapers. 
     Therefore, the battery  101  can be held without detachment even when impact such as dropping occurs without using a separate member for restricting movement of the battery  101  in the sectional direction, further, there is achieved an effect that the mountability of the battery  101  to the eaves portions  103   a  through  109   a  projected long to the side of the opening portion  113 , is excellent. 
     Further, the structure can be simplified by reducing a number of parts, further, since a number of integrating steps can be reduced, shortening of a time period of integration and therefore, a reduction in cost can be achieved. 
     Further, it is not necessary to arrange a part such as a battery holder to laminate on the battery  101  and therefore, the electronic timepiece can be thinned. 
     Furthermore, by integrally molding the battery frame  102  and the eaves portions  103  through  109  by insulating resin, an insulating plate or the like is dispensed with. 
     Further, although according to the specific example, the button battery  101  is used as the battery  101 , a battery having other shape may be used. Further, although an explanation has been given of the example of the electronic wristwatch, the invention is applicable not only to the electronic wristwatch of a digital display type or an analog display type but also to various electronic timepieces of a battery drive type such as a-wall type electronic timepiece, a desk-top type electronic timepiece and so on. 
       FIG. 4  is a plane view showing other specific example of a battery holding structure of an electronic timepiece according to the invention and  FIG. 5  is a front sectional view taken along a line E—E of FIG.  4 . Further, in both of the drawings, the same portions are attached with the same notations and portions the same as those of FIG.  1  through  FIG. 3  are attached with the same notations. Further,  FIG. 4  shows a drawing omitting a case back. 
     A difference between the specific example and the specific example shown in FIG.  1  through  FIG. 3 , resides in forming projected portions  501  through  507  integrally with the respective eaves portions  103   a  through  109   a  in order to firmly prevent positional shift in the sectional direction or detachment of the battery  101 , the method of inserting and holding the battery  101  and the like stays the same and therefore, an explanation will mainly be given of the plurality of projected portions  501  through  507  as follows. 
     In FIG.  4  and  FIG. 5 , the respective projected portions  501  through  507  are molded by insulating resin and molded integrally with the respective eaves portions  103   a  through  109   a  on sides of a cover member or case back  601  of the respective eaves portions  103   a  through  109   a . Front end portions of the projected portions  501  through  507  are constituted to project to the side of the openign portion  113  more than inner wall faces  602  of the arm portions  103   b  through  109   b  of the engaging portion  103  through  109  and are constituted to be brought into contact with the case back  601  at positions projected to the side of the opening portion  113  more than the inner wall faces  602 . Further, there is constructed a constitution in which in a state of completing the electronic timepiece by mounting the case back  601  of the electronic timepiece, the case back  601  is brought into contact with the projected portions  501  through  507 . 
     According to the above-described constitution, when the case back  601  is mounted to a main body of the electronic timepiece in a state in which the battery  101  is contained and held at inside of the opening portion  113  of the battery frame  102 , first, the case back  601  is brought into contact with the projected portions  501  through  507 . Under the state, when the case back  601  is mounted to the main body of the electronic timepiece, the case back  601  is mounted to the main body of the electronic timepiece in a state of pressing the projected portions  501  through  507 . At this occasion, the projected portions  501  through  507  are brought into contact with the case back  601  at the positions projected to the side of the opening portion  113  more than the inner wall faces  602  and therefore, the eaves portions  103   a  through  109   a  are bent in the direction of the battery  101  by press force of the case back  601 . The battery  101  is solidly held in the state of being pressed by the eaves portions  103   a  through  109   a  at inside of the opening portion  113  of the battery frame  102 . 
     Therefore, the specific example not only achieves an effect similar to that of the above-described specific example but also movement of the battery  101  in the sectional direction can firmly be restricted by the eaves portions  103   a  through  109   a  and therefore, even when the electronic timepiece undergoes impact as in the case of dropping the electronic timepiece, the battery  101  can further firmly be prevented from being shifted positionally or detached. 
     Further, the projected portions  501  through  507  are brought into contact with the case back  601  at the positions projected to the side of the opening portion  113  more than the inner wall faces  602  and therefore, the eaves portions  103   a  through  109   a  can firmly be pressed to the side of the battery  101  and the battery  101  can be held further firmly. Therefore, an electronic timepiece excellent in impact resistance can be constituted. 
     Further, it is not necessarily needed to provide the projected portions  501  through  507  at all of the eaves portions  103   a  through  109   a  but at least three of the projected portions may be arranged with excellent balance. Further, pluralities of the projected portions  501  through  507  may be arranged at the respective eaves portions  103   a  through  109   a . Further, it is also possible to construct a constitution such that the projected portions  501  through  507  are not projected to the side of the opening portion  113  more than the inner wall faces  602  and are brought into contact with the case back  601  at positions at which the projected portions  501  through  507  are not projected to the side of the opening portion  113  from the inner wall faces  602 . Also in this case, the arm portions  103   b  through  109   b  are bent by press force of the case back  601  to thereby press the eaves portions  103   a  through  109   a  to the battery  101 , thereby, the positional shift of the battery  101  in the sectional direction is prevented. 
     INDUSTRIAL APPLICABILITY 
     As described above, the battery holding structure of the electronic timepiece according to the invention is applicable not only to the electronic wristwatch of a digital display type or an analog display type but also to various electronic timepieces of a battery drive type such as a wall type electronic timepiece, a disk-top type electronic timepiece and so on.