Abstract:
A crown lock structure for a timepiece has a crown having an inner surface provided with a threaded section and a connecting assembly for removably connecting the crown to a case of the timepiece. The connecting assembly comprises a tubular member for integral connection to the timepiece case and a tubular insert removably connected to the tubular member. The tubular member has a first tubular portion for insertion into a through-hole of the timepiece case and a second tubular portion integral with the first tubular portion and removably connected to the tubular insert so as to prevent relative rotation between the tubular member and the tubular insert. The tubular insert has a threaded section for threaded engagement with the threaded section of the crown to removably connect the crown to the timepiece case.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to timepieces and, more specifically, to a crown structure for a timepiece, such as a portable watch, which prevents the crown from being accidentally rotated. 
   2. Description of the Prior Art 
   In a portable watch exemplified by a divers watch, adopted is the structure in which a crown is locked utilizing a screw engagement (such a structure is referred to as a screw lock in this specification) to prevent the crown from accidentally rotating when the portable watch is carried around. 
   The screw lock structure is the structure in which a case including a watch movement is attached with a winding stem pipe, and to a male screw section formed to the outer rim of an extracase end section of the pipe, a female screw section locating at a crown main section to be fit to the extracase end section is screwed. With such a structure, under normal circumstances, the crown main section is screwed into the outer rim of the extracase end section so that the crown is locked. In order to operate the watch movement, the crown main section is unscrewed from the male screw section, and after pulling out the crown, a winding stem locating inside of the winding stem pipe can be operated for rotation. 
   With the conventional portable watch of such a screw lock structure, generally, a winding-stem-pipe-attachment section can be made waterproof by brazing the winding stem pipe to the case (see JP-A-57-4681 (from 8th line, right column, page 1 to 7th line, left column, page 2, FIGS. 1 and 2) as an example). 
   Other than the above, also known is another portable watch of a type aiming for waterproof capability of the winding-stem-pipe-attachment section. Therein, in the middle part of the winding stem pipe in the axial direction, a male screw section is provided separately from another male screw section to which a crown is screwed together so that the male screw section is screwed into the pipe-attachment hole of the case, and after this screwing is completed, a waterproof gasket is sandwiched between the case and the winding stem pipe. 
   In a portable watch with the screw lock structure, repeatedly operating the crown for rotation will cause both the screwed-together female screw section of the crown and the male screw section of the winding stem pipe to be worn out or chipped, resultantly reducing the screw lock capability. 
   In such a case, the portable watch of JP-A-57-46181 in which the case is brazed with the winding stem pipe does not allow exchange of components locating close to the crown if requiring removal of the winding stem pipe from the case. There is thus no choice to exchange the watch exterior assembly including the case. As such, there has been a demand for improvement thereof. 
   With a watch having a winding stem pipe screwed into a case, it has been considered that, in principle, exchange is possible for components including the winding stem pipe, locating close to the crown. Even with such a structure, however, the winding stem pipe receives rotation forces every time the crown is screwed into the winding stem pipe or every time this screwing is unscrewed. Accordingly, the screwing of the winding stem pipe into the case becomes loose, resultantly possibly causing the waterproof capability achieved by a waterproof gasket to be reduced. 
   As measures against that, adhesive filling is sometimes done to the section at where the winding stem pipe and the case are screwed together. If adhesive is used for attachment as such, the winding stem pipe becomes difficult to be removed from the case, and in practical sense, exchange of components locating close to the crown becomes impossible. As a result, there has been no choice to exchange the watch exterior assembly including the case if the screw lock capability is reduced. As such, there has been a demand for improvement thereof. 
   An object to be achieved by the present invention is to provide a portable watch capable of exchange of components locating close to the crown when the screw lock capability is reduced. 
   SUMMARY OF THE INVENTION 
   In order to achieve the above object, the present invention is characterized in that a winding stem pipe fixed to a case for screw locking a crown is provided with: a winding stem pipe body inserted into a pipe-attachment hole of the case to be fixed to the case to be watertight; and an exterior pipe whose outer rim plane is formed with a male screw section to be screwed together with a female screw section of the crown in a removable manner, and to the outer rim of an extracase end section of the winding stem pipe body to be arranged outside of the case, the exterior pipe is prevented from rotating and fit thereto in a removable manner. 
   In the present invention, the winding stem pipe is fixed to the case not to be separated therefrom. On the other hand, the exterior pipe screwed together with the female screw section of the crown for screw locking the crown is removable from the extracase end section of the winding stem pipe body. With such a structure, if the screw lock capability is reduced responding to the crown operation for exerting or releasing the screw lock capability, the crown and the exterior pipe can be separately exchanged with the winding stem pipe body fixed to the case. In a preferred embodiment of the present invention, each of the winding stem pipe body and the exterior pipe is made of a different material. Thus, it is considered superior in the respect that the design flexibility can be improved by allowing the winding stem pipe body and the exterior pipe to be made of any appropriate material corresponding to their own capabilities. 
   In the preferred embodiment of the present invention, the exterior pipe is made of a material better in abrasion resistance than that of the winding stem pipe body. Accordingly, with no limitation on the material of the winding stem pipe body, it is considered superior in that the screw lock structure can be improved in durability. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred form of the present invention is illustrated in the accompanying drawings in which: 
       FIG. 1  is a front view of a divers watch according to an embodiment of the present invention; 
       FIG. 2  is a cross-sectional view cut along an F 2 -F 2  line in  FIG. 1  with a crown screw locked; 
       FIG. 3  is a front view of a winding-stem-pipe-attachment section with the crown of the divers watch of  FIG. 1  removed; 
       FIG. 4  is a perspective view of a winding stem pipe of the divers watch of  FIG. 1 ; and 
       FIG. 5  is an exploded perspective view of a winding stem pipe of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description, an embodiment of the present invention will be described with reference to  FIGS. 1 to 5 . 
   A reference numeral  11  in  FIG. 1  shows a divers watch as a portable watch equipped with the screw lock structure for a crown. This watch  11  accommodates a watch movement, and the like, that is not shown in a watch exterior assembly  12 . The type of watch movement is not restrictive, and may be of a type whose power source is a small-sized battery or a spring, a self-winding type, of a type equipped for a digital watch displaying time or other information in digital form on a dial using a quartz oscillator module, or a type which combines a digital watch with one or more other types of watch movements. 
   The watch exterior assembly  12  is so formed that a cover glass  14  is attached to be watertight over the surface of an annular metallic case  13  in the thickness direction, and a case back  15  (refer to  FIG. 2 ) made of metal, and the like, is attached to be watertight over the back plane of the case  13 . A dial  16  and other components can be seen through the cover glass  14 , and the case back  15  can be removable. 
   As shown in  FIG. 2 , the case  13  has, at a part thereof, a through-hole in the form of a pipe-attachment hole  17  going through the case  13  in the radius direction. One end of the pipe-attachment hole  17  opens to an interior surface of the case  13  at an intracase side, that is, to inside of the watch exterior assembly  12 . The other end of the pipe-attachment hole  17  opens to an exterior surface  13   a  of the case  13  at an extracase side, that is, to outside of the watch exterior assembly  12 . The exterior surface or extracase plane  13   a  of the case  13  includes an accommodation groove  18 . This accommodation groove  18  is made larger in diameter than the pipe-attachment hole  17 , and goes through the opening made on the extracase side of the hole  17  and is provided concentrically with the opening.  18  is made larger in diameter than the pipe-attachment hole  17 , and goes through the opening made on the extracase side of the hole  17  and is provided concentrically with the opening. 
   To the case  13 , a connecting assembly comprised of a winding stem pipe  21  is fixed from the extracase side to be watertight by extending through the pipe-attachment hole  17 . 
   In detail, as shown in  FIGS. 2 ,  4 , and  5 , the winding stem pipe  21  is comprised of a tubular member defining a winding stem pipe body  22  and a tubular insert comprising an exterior pipe  26  slidably inserted over the winding stem pipe body  22 . 
   The winding stem pipe body  22  is made of metal, and a preferable exemplary usage option therefor is stainless steel. This winding stem pipe body  22  is provided with an inner insertion section  23  at one end thereof, and an outer or extracase end section  24  at the other end thereof. The insertion section  23  is the part to be inserted into the pipe-attachment hole  17  with a, press-fit from the extracase side, and at the outer rim of the tip part thereof, a taper plane  23   a  in tapered form is provided. The outer or extracase end section  24  is the part to be arranged outside of the case  13 , and is made to be square- or hexagon-shaped, for example. The diameter of this extracase end section  24  is larger than the outer diameter of the insertion section  23  and the diameter of the accommodation groove  18 . To the end part locating opposite to the side abutting to the extracase plane  13   a  of the extracase end section  24 , a stopper-attachment section, for example, an annular groove  24   b  as shown in  FIG. 5  is formed. 
   The winding stem body  22  is inserted into the pipe-attachment hole  17  until the extracase end section  24  abuts the extracase plane  13   a . At the same time, it is fixed to the case  13  not to be separated therefrom by a metallic brazing material  25  filled to the accommodation groove  18 . The brazing material  25  used for fixation functions also to provide a waterproof seal between the case  13  and the winding stem pipe body  22 . 
   In the present embodiment, although the insertion section  23  extends through the pipe-attachment hole  17 , it may have a length so as to not extend through the attachment hole  17 . Further, as to the insertion section  23 , the major diameter thereof may be the base side part closer to the extracase end section than the tip side part thereof, and corresponding thereto, the accommodation groove  18  may be so formed as to be deep enough to accept the base part, and the brazing material  25  is filled into between the step height part formed by the tip side part and the base part and the further set part of the accommodation groove  18  for fixing the winding stem pipe body  22  to the pipe-attachment hole  17  to be watertight. Alternatively, instead of the brazing, to achieve watertight fixation, a rubber waterproof gasket may be sandwiched between the case  13  and the winding stem pipe body  22  to screw the insertion section  23  into the pipe-attachment hole  17 , and the pipe-attachment hole  17  and the insertion section  23  may be attached together using an adhesive. 
   As shown in  FIG. 5 , inner rim planes or flat sections  26   a  of the exterior pipe  26  define a hole corresponding to the shape of complementary outer rim planes or flat sections  24   a  of the extracase end section  24 . This exterior pipe  26  is fit to the extracase end section  24  in a removable manner. The inner rim planes or flat sections  26   a  of the exterior pipe  26  and the complementary outer rim planes or flat sections  24   a  of the extracase end section  24  are configured to abut each other. With such a structure, the exterior pipe  26  is prevented from rotating in the circumferential direction with respect to the extracase end section  24 . 
   Therefore, the outer rim planes  24   a  of the extracase end section  24  and the inner rim planes  26   a  of of the exterior pipe  26  form polygon shapes and define rotation-stop means for the exterior pipe  26 . It is understood, however, that the structure of the rotation-stop means is not limited to the foregoing structure. For example, the rotation-stop means can be structured by, for example, one or more keys extending in the axial direction of the pipe and a key groove(s) to be fit thereinto to freely swing, or may be structured by achieving fixation utilizing serration. 
   To the annular groove  24   b  of the extracase end section  24 , for example, a stopper member comprised of an E-shaped stopper  27  shown in  FIGS. 2 to 4  is attached. In the present embodiment, the annular groove  24   b  protrudes to the side outer than the end plane of the exterior pipe  26  when the exterior pipe  26  is fit into the extracase end section  24 . And the end plane of the exterior pipe  26  is formed to such a position as to be pressed by the stopper  27 . The stopper  27  can be attached or removed to/from the annular groove  24   b  by changing in shape due to its elasticity using a tool, which is not shown. The outer diameter of this stopper  27  is made smaller than the trough diameter of a threaded or a male screw section  28 , which will be described later, to avoid any interference with a female screw section  35  of the crown, which will be described later. The stopper  27  is used as stopper means for pressing the end plane of the exterior pipe  26 , and for preventing the exterior pipe  26  from being disengaged in the axial direction with respect to the extracase end section  24 . Here, this not restrictive, and a possible option for the stopper means may be a board nut for pressing the end plane of the exterior pipe  26  by being screwed together in a removable manner with a screw section provided to the part out of the region of the extracase end section  24  to which the exterior pipe  26  is fitted, for example. 
   As described in the foregoing, to the outer rim plane of the exterior pipe  26 , which is fit in a removable manner to the outer rim of the extracase end section  24  for preventing rotation, there is provided the male screw section  28  for screw locking. 
   The exterior pipe  26  is made of the same material as for the winding stem pipe body  22  or from different material. When the exterior pipe  26  is made of the same material (e.g., stainless steel) as that of the winding stem pipe body  22 , it is considered superior in the respect that no electrical rust occurs as in the case where metals of different types abut one another. When the exterior pipe  26  is made of a different material from that of the winding stem pipe body  22 , the winding stem pipe body  22  and the exterior pipe  26  can be made of any appropriate material corresponding to their own capabilities. As such, it is considered superior in the respect that the design flexibility can be improved. What is more, if any different material is used, the exterior pipe  26  may be made of a material better in abrasion resistance than the winding stem pipe body  22  without being restricted by the material of the winding stem pipe body  22 . As such, there is no need to make the winding stem pipe  21  in its entirety with any material between in abrasion resistance, and thus it is considered superior in the respect that the screw lock structure durability can be improved with low cost. 
   The winding stem pipe  21  structured as above is attached to the case  13  by, as described in the foregoing, inserting the insertion section  23  of the winding stem pipe body  22  into the pipe-attachment hole  17  of the case  13  for brazing with the extracase end section  24  of the winding stem pipe body  22  attached in advance with the exterior pipe  26  and the stopper  27  as shown in  FIG. 4 . Alternatively, attachment to the case  13  can be done by inserting only the winging stem pipe body  22  to the pipe-attachment hole  17  of the case  13  for brazing, the exterior pipe  26  is fitted to the extracase end section  24  arranged outside of the case  13 , and then the annular groove  24   b  is attached with the stopper  27 . 
   A crown denoted by a reference numeral  31  in  FIG. 1  is made of metal, and as shown in  FIG. 2 , is provided with a crown main section  32  and a crown tube section  33  extending in its entirety in the axial direction from the middle section thereof. To the crown main section  32 , an annular clearance groove  34  is provided to enclose the base section of the crown tube section  33 . A threaded or female screw section  35  is formed to the inner rim plane of the groove  34  for screw locking. The clearance groove  34  is a part into which the extracase end section  24  and the exterior pipe  26  of the winding stem pipe  21  are inserted. The female screw section  35  is screwed together with the male screw section  28  of the exterior pipe  26  in a removable manner. Through such screwing, provided is the capability for the screw lock not to allow the crown  31  to accidentally rotate when the watch  11  is carried around. 
   The crown tube section  33  is inserted into the winding stem pipe  21  from the extracase side. To an annular gasket attachment groove formed to the outer rim of the tube section  33 , a waterproof member comprised of an annular waterproof rubber gasket  36  is attached. The waterproof gasket  36  is sandwiched between the inner rim plane of the winding stem pipe  21  and the outer rim plane of the crown tube section  33  by changing in shape due to its elasticity through compression, for the purpose of achieving waterproof therebetween. The crown tube section  33  receives a winding stem  37  of the watch movement from the interacase side, and accommodates a coil spring  39  for biasing the winding stem  37  in the axial direction via a spring bearing  38 . The watch movement rotates in relation with the rotation operation of the crown  31  with the female screw section  35  being disengaged from the second male screw section  28 , in other words, with the screw lock released. In such a manner, time adjustment and other functions are carried out. 
   Herein, as to the crown  31 , the crown tube section  33  thereof is inserted into the winding stem pipe  21  from the extracase side with the winding stem  37  connected thereto, and the female screw section  35  of the crown main section  32  is screwed and clamped with the male screw section  28  of the exterior pipe  26 . In this manner, attachment is done. When the crown  31  is screwed into the male screw section  28  to the furtherest point, the position of the crown main section  32  is defined when it abuts the extracase plane  13   a  of the case  13  as shown in  FIG. 2  so that the extracase plane  13   a  of the case  13  as shown in  FIG. 2  so that the exterior pipe  26  is entirely covered. Here, after such a procedure is complete, the winding stem  37  and the watch movement are connected together. 
   With such assembly completed, the waterproof capability can be exerted and retained under high pressure. That is, a waterproof seal between the winding stem pipe  21  and the case  13  can be secured thanks to the brazing material  25  used for their fixation, and a waterproof seal between the winding stem pipe  21  and the crown tube section  33  internally inserted thereinto can be secured thanks to the waterproof gasket  36  sandwiched therebetween by changing in shape due to its elasticity through compression. 
   In the divers watch  11  assembled as shown in  FIG. 2 , the crown  31  is engaged with the male screw section  28  of the winding stem pipe  21  for screw lock. This prevents the crown  31  from accidentally rotating when carried around, whereby time display and others do not change. For time adjustment, for example, the crown  31  is rotated in the reverse direction so as to disengage the crown main section  32  from the male screw section  28 . Thus, for the purpose, the crown  31  is pulled out against the spring forces of the coil spring  39 . 
   Responding to the operation of the crown  31 , if the screw lock capability of the crown  31  is reduced due to damage or wear-out of the male screw section  28  and the female screw section  35  screwed thereinto, it can be dealt with as follows. 
   That is, the stopper  27  can be removed from the annular groove  24   b  of the extracase end section  24  of the winding stem pipe body  22 , and through removal as such, the exterior pipe  26  having fitted to the extracase end section  24  becomes able to be removed from the extracase end section  24  by being pulled out along the axial direction of the winding stem pipe body  22  brazed to the case  13 . Therefore, when the screw lock capability is reduced, the exterior pipe  26  including the male screw section  28  of the winding stem pipe  21  and the crown  31  attachable or removal thereto/therefrom can be separately exchanged. 
   Accordingly, during a repairing operation, there is no need to exchange the watch exterior assembly  12  including the case  13 , and the like, even if the screw lock capability is reduced. Thus, only the damaged component needs to be exchanged, thereby favorably reducing costs. 
   As described in the foregoing, with the winding stem pipe body  22  fixed to the case  13 , the exterior pipe  26  of the winding stem pipe  21  can be exchanged. For exchange, as exchange components, a plurality of types of exterior pipes having the same inner rim plane shape but varying in the diameter, pitch, the number of threads, and others of the male screw section  28  may be prepared in advance. Also, the crown  31  including the female screw section each corresponding to these male screw sections  28  may be prepared for a plurality of types. In such a case, exchange is not restrictive to those of the same type as the exterior pipe  26  and the crown  31  which is damaged and discarded after use. However, exchange to any new exterior pipe  26  and crown  31  of the same type arbitrarily selected among the plurality of types is possible. This eases component management for manufacturers because there is no more need to store the exchange components for a long period of time. 
   The present invention is not restricted to the above embodiment. For example, it can be applied to portable watches such as normal wrist watches or pocket watches that do not require waterproof capability under high pressure. 
   In the present invention, with respect to an extracase end section of a winding stem pipe body fixed to a case to be watertight not to be separated therefrom, an exterior pipe for screw locking a crown through screwing with a female screw section is prevented from rotation, thereby rendering it removable. Thus, according to the present invention, when the screw lock capability is reduced responding to the crown operation, provided is a portable watch capable of exchanging separately components around the crown, that is, the crown and the exterior pipe for screw locking it with the winding stem pipe body fixed to the case. 
   According to the present invention in which a winding stem pipe and an exterior pipe are each made of a different material, provided is a portable watch with which the design flexibility can be improved by allowing the winding stem pipe body and the exterior pipe to be made of any appropriate material corresponding to their own capabilities. 
   According to the present invention in which an exterior pipe is made of a material better in abrasion resistance than a winding stem pipe body, provided is a portable watch capable of improving the durability of the screw lock structure with no limitation on the material of the winding stem pipe body.