Patent Publication Number: US-7591582-B2

Title: Watch and crown used in this watch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a watch equipped with a structure for holding the crown to prevent it from being inadvertently rotated and to a crown used in such a watch. 
     2. Description of the Prior Art 
     In some watches such as wristwatches, the crown is locked by making use of threaded engagement to prevent inadvertent rotation of the crown when carrying the watch (the structure or function is referred to as threadedly locking, threadedly locking structure, or threadedly locking function in the present specification). 
     In the threadedly locking structure, a stempipe is mounted to a barrel in which a watch movement is incorporated. The internal thread of the crown which is fitted over a barrel outside protruding portion is threadedly engaged to an external thread formed on the outer surface of the barrel outside protruding portion of this pipe. In this way, during normal times, the crown is threadedly engaged to the outer surface of the barrel outside protruding portion. Thus, threadedly locking is achieved, preventing inadvertent rotation of the crown. Also, when the watch movement is manipulated, the crown is threadedly disengaged from the external thread and then the crown is pulled and moved. Under this condition, the stem located inside the stem pipe can be rotationally manipulated via the crown. 
     The crown of the conventional watch equipped with such a threadedly locking structure consists of a single part. In particular, it is composed of an inner cylindrical body and an outer cylindrical body integral with it. The inner cylindrical body is a portion inserted into a stem pipe mounted to a barrel from outside of the barrel. The outer cylindrical body is shorter than the inner cylindrical body and covers an end part of this inner cylindrical body. An inner thread portion is formed in the inner surface of this outer cylindrical body. The crown is threadedly locked by bringing this inner thread into threaded engagement with an external thread formed on the outer surface of a barrel outside protruding portion of the stem pipe and bringing an end surface of the outer cylindrical body into abutment with a barrel outer surface (see, for example, Japanese Utility Model Application No. 7-26792). 
     The crown of the integrated structure described in Japanese Utility Model Application No. 7-26792 has a wall portion connecting its outer cylindrical body and inner cylindrical body integrally. This wall portion hinders insertion of a tapping tool beyond a certain extent when an internal thread is machined on the outer cylindrical body using the tapping tool such as a tap. 
     In this way, in threading machining for forming an internal thread on the outer cylindrical body of a crown, a care needs to be taken to prevent the tapping tool from striking the wall portion. Therefore, it is difficult to machine the crown. Consequently, this machining is disadvantageous in terms of cost. 
     Since the workability (machinability) of the threading machining is poor as described above, the accuracy at which internal threads are machined varies widely. As a result, there may occur a combination in which the accuracy of threaded engagement between the external thread of the stem pipe and the internal thread of the crown is low. In this case, as the crown is rotationally manipulated, the life of the threadedly engaging portion may be shortened. 
     Furthermore, because of the size of the crown that is a small part, 3 to 4 thread ridges can be formed at maximum on the internal thread formed on the outer cylindrical body. During manufacturing, the tapping tool makes the internal thread without passing through the outer cylindrical body. Therefore, those portions of this internal thread which are close to the wall portion are incompletely threaded portions. Consequently, as threadedly locking is done by bringing the external thread of the stem pipe and the internal thread of the crown into mesh each other, the incompletely threaded portions of the internal thread portion deform the external thread. This may lead to a decrease in the life of the threadedly engaging portion. 
     It is an object of the present invention to provide a watch which is capable of improving the life of the threadedly engaging portion between a stem pipe and a crown and which permits easy and accurate machining of an internal thread on the crown, as well as the crown used in this watch. 
     SUMMARY OF THE INVENTION 
     To solve the foregoing problem, a watch according to the present invention comprises a barrel; a stem pipe disposed outside the barrel and having a barrel outside protruding portion provided with an external thread, the stem pipe being mounted to the barrel; and a crown ring having a crown shaft and an internal thread removably threaded to the external thread. The crown shaft has a barrel insertion cylindrical portion inserted in the stem pipe and a ring connection portion mounted integrally with the cylindrical portion, the barrel insertion cylindrical portion being smaller in diameter than the crown ring. The ring connection portion is connected to an end portion of the crown ring. 
     In the present invention, the crown does not have an integrated structure consisting of a single part but has a structure having two parts, i.e., a crown ring and a crown shaft. Therefore, an internal thread for threadedly locking can be machined by passing a tapping tool through inside of the ring when the crown ring is in a single state. Consequently, threading machining can be performed easily. Concomitantly, the machining accuracy can be enhanced. In addition, the whole internal thread can be made a completely threaded portion. Accordingly, by using a crown fabricated by connecting the crown ring and the crown shaft passed through inside it, the accuracy of the threaded engagement between the internal thread of the crown and the external thread of the barrel outside protruding portion of the stem pipe can be enhanced. In addition, as the crown is rotationally manipulated, damage to the threadedly engaging portion between the internal thread of the crown and the external thread of the barrel outside protruding portion can be suppressed. 
     In a preferred embodiment of the watch of the present invention, the crown shaft and the crown ring are made of dissimilar materials. 
     In this preferred embodiment, the crown ring having the internal thread can be fabricated from a material adapted for threaded engagement such as a wear-resistant material without being restricted by the material of the crown shaft. 
     Furthermore, in a preferred embodiment of the watch of the present invention, the crown ring and the crown shaft are made different in color. 
     In this preferred embodiment, various color variations are adapted to be given to the crown according to the design required for the crown, instead of a single color tone. 
     In this case, the crown ring and the crown shaft may be made of dissimilar materials having different color tones. Alternatively, if they are made of the same material, a color layer formed by surface treatment such as plating may be formed on at least one of them and practiced. Where the color layer is formed by plating, the corresponding crown ring or the like may be plated with a metal while it is in a single state. At this time, it is not necessary to mask the other crown shaft. Consequently, the color layer can be formed easily. 
     In addition, in a preferred embodiment of the watch of the present invention, the crown ring is provided with a coupling hole having a diameter larger than that of the internal thread. The ring connection portion has a connecting internal thread portion threaded into a part of the external thread and a press-fitted portion press fitted in the coupling hole by threaded engagement between the connection external thread portion and the internal thread. 
     In this preferred embodiment, the crown shaft and the crown ring can be connected by bringing the connecting external thread portion of the crown shaft into mesh with a part of the internal thread of the crown ring. In addition, because of the threaded engagement, the press-fitted portion of the crown shaft is pulled into the coupling hole in the crown ring and press fitted into this coupling hole. Therefore, the crown shaft and the crown ring can be connected even in this engaging portion. Consequently, the crown shaft and the crown ring are connected more reliably. As the crown is manipulated, the danger that the threadedly engaged portion between the crown shaft and the crown ring loosens can be eliminated. 
     In addition, to solve the foregoing problem, a crown for a watch of the present invention comprises a crown shaft and a crown ring having an internal thread in its inner surface. The crown shaft has a barrel insertion cylindrical portion of a diameter smaller than that of the crown ring and a ring connection portion mounted integrally with this cylindrical portion and connected to an end portion of the crown ring. 
     The crown of the present invention consists of two parts, i.e., a crown ring and a crown shaft, instead of a single part. An internal thread for threadedly locking can be machined by passing a tapping tool through inside of this ring when the crown ring is in a single state. In consequence, threading machining can be simply performed. Concomitantly, the machining accuracy can be enhanced. In addition, the whole internal thread can be made a completely threaded portion. Accordingly, the crown fabricated by connecting this crown ring and the crown shaft passed through inside thereof is used as a crown for threadedly locking in a watch. This can enhance the accuracy of threaded engagement between the internal thread of this crown and the external thread of the barrel outside protruding portion of the stem pipe. As the crown is rotationally manipulated, damage to the threadedly engaged portion between the internal thread of the crown and the external thread of the barrel outside protruding portion can be suppressed. 
    
    
     
       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 front elevation showing a wristwatch associated with one embodiment of the present invention; 
         FIG. 2  is a cross-sectional view shown along the line Z-Z through  FIG. 1  in a state in which the crown has been threadedly locked; 
         FIG. 3  is a cross-sectional view shown along the line Z-Z through  FIG. 1  in a state in which the crown has been threadedly unlocked; 
         FIG. 4  is an exploded perspective view of the crown of a wristwatch associated with one embodiment; and 
         FIG. 5  is a perspective view showing the crown of a wristwatch associated with one embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the present invention is described by referring to  FIGS. 1-5 . 
     In  FIG. 1 , symbol  11  indicates a watch equipped with a function of threadedly locking the crown such as a wristwatch. The wristwatch  11  incorporates a watch movement (not shown) or the like in a watch outer assembly  12 . The watch movement may be any one of a movement powered by a small-sized battery or spring, an automatically wound movement, a movement corresponding to a digital watch that uses a quartz oscillation module and digitally displays the time and so forth on a dial, and a combination of a movement corresponding to a digital watch with others. 
     The watch outer assembly  12  has a watch case in the form of an annular barrel  13  made of a metal, such as stainless steel or titanium, or synthetic resin. A cover glass  14  is mounted to the whole surface of the barrel in the direction of thickness in a liquidtight manner. A rear cover  15  (see  FIGS. 2 and 3 ) made of a metal or the like is mounted to the rear surface of the barrel  13  in the direction of thickness in a liquidtight manner. It is possible to see through the dial  16  and so on via the cover glass  14 . The rear cover  15  can be removed. 
     As shown in  FIGS. 2 and 3 , a pipe installation hole  17  extending radially through the barrel  13  is formed in a part of the barrel  13 . One end of the pipe installation hole  17  opens into the barrel, i.e., into the inside of the watch outer assembly  12 . The other end of the pipe installation hole  17  opens to the outside of the barrel, i.e., outside of the watch outer assembly  12 . 
     A stem pipe  21  inserted into the pipe installation hole  17  from outside of the barrel is fixed to the barrel  13  in a liquidtight manner. A metal such as stainless steel can be preferably used as the stem pipe  21 . The stem pipe  21  has an insertion portion  21   a  at one end side and a barrel outside protruding portion  21   b  at the other end side. The insertion portion  21   a  is inserted and fixed in the pipe installation hole  17  from outside of the barrel. In the present embodiment, the insertion portion  21   a  is inseparably fixed to the barrel  13  using a metallic brazing material  22 . The brazing material  22  assuming the function of the fixing also acts as a member for maintaining the liquidtightness to provide waterproofness between the barrel  13  and the stem pipe  21 . 
     Instead of this, the insertion portion may be fixed in a watertight manner by forming an internal thread in the pipe installation hole  17 , forming an external thread upon the insertion portion, bringing these threaded portions into mesh with each other, and providing waterproof packing at a position where the brazing material is applied. Furthermore, the stem pipe  21  can also be fixed to the barrel  13  by other fixing means. The insertion portion  21   a  may have a length sufficient to extend through the pipe installation hole  17 . 
     The barrel outside protruding portion  21   b  is a portion located outside the barrel  13  and is larger in diameter than the insertion portion  21   a . An external thread  23  is formed on the outer surface of the barrel outside protruding portion  21   b . The end surface of the barrel outside protruding portion  21   b  on the insertion portion side is in abutment with a barrel outer surface  13   a.    
     A crown indicated by symbol  31  in  FIGS. 1 to 5  is fabricated by connecting a crown shaft  32  and a crown ring  33 . The crown shaft  32  and the crown ring  33  are made of similar or dissimilar metal materials. Examples of the used metals include stainless steel and titanium. Of the crown shaft.  32  and the crown ring  33 , at least the crown ring  33  has a color layer formed by surface treatment such as metal plating treatment and can be made different in color from the barrel  13  or crown shaft  32 . 
     As shown in  FIGS. 2-4 , the crown shaft  32  has a barrel insertion cylindrical portion  32   a  and a ring connection portion  32   b . The diameter of the barrel insertion cylindrical portion  32   a  is smaller than the inside diameter of the crown ring  33 . Its one end in the axial direction is open. The ring connection portion  32   b  is larger in diameter than the barrel insertion cylindrical portion  32   a  but smaller than the outside diameter of the crown ring  33 . This ring connection portion  32   b  is mounted integrally with the other end of the barrel insertion cylindrical portion  32   a  in the axial direction. 
     The ring connection portion  32   b  has a connection threaded portion  34  in the form of external thread and a press-fitted portion  35  on its outer surface. This ring connection portion  32   b functions as a closing end portion for closing off one end portion of the crown ring  33 . The connection threaded portion  34  is totally made of a completely threaded portion. This connection threaded portion  34  is mounted in a position closer to the barrel insertion cylindrical portion  32   a  than the press-fitted portion  35 . The press-fitted portion  35  is mounted in a position further from the barrel insertion cylindrical portion  32   a  than the connection threaded portion  34 . The press-fitted portion  35  is larger in diameter than the connection external threaded portion  34 , is circular as shown in  FIG. 4 , and forms a maximum diametrical portion of the ring connection portion  32   b . 
     The crown ring  33  is shorter in length than the crown shaft  32 . An internal thread  36  for threadedly locking is formed on the inner surface of the crown ring  33 . A coupling hole  37  larger in diameter than the inside diameter of the crown ring  33  is formed in the crown ring  33 . As shown in  FIG. 4 , the coupling hole  37  is in the form of an annular groove and has a deep surface  37   a  continuous with one end of the internal thread  36  and is open to one end of the crown ring  33 . Unevenness is formed on the outer surface of the crown ring  33  to prevent the user&#39;s finger from slipping when the crown is manipulated. 
     The crown shaft  32  and the crown ring  33  are connected by passing the crown shaft  32  through inside of the crown ring  33 , bringing the connection threaded portion  34  into mesh with one end portion of the internal thread  36  to thereby pull the press-fitted portion  35  into the coupling hole  37 , and press fitting the press-fitted portion into the hole. In this manner, the crown ring  33  is positioned circumferentially around and connected to the outer end portion of the crown shaft  32 . 
     In this assembly, the threaded engagement between the connection threaded portion  34  and the internal thread  36  and the engagement between the press-fitted portion  35  and the coupling hole  37  ensure the connection between the crown shaft  32  and the crown ring  33 , thus assembling the crown  31 . Therefore, it is possible to eliminate the danger that the threadedly engaged portion between the crown shaft  32  and the crown ring  33  is loosened as the crown is manipulated as described later. 
     For further prevention of loosening, adhesive is permitted to be supplementarily entered between the press-fitted portion  35  and the coupling hole  37  to fix them together. Furthermore, in the present invention, in a case where the crown shaft  32  and the crown ring  33  are made of the same metal, the connection threaded portion  34  of the crown shaft  32  may be omitted, and the engaging portions of the press-fitted portion  35  and the coupling hole  37  may be welded together. Where the crown shaft  32  and the crown ring  33  are made of the same metal, the connection threaded portion  34  of the crown shaft  32  may be omitted, and the engaging portions of the press-fitted portion  35  and the coupling hole  37  may be fixed together with adhesive. 
     As described so far, the crown  31  is not a single part but is fabricated by connecting two parts, or the crown shaft  32  and the crown ring  33 . Therefore, the internal thread  36  for threadedly locking can be machined by inserting a tapping tool (not shown) such as a tap into the inner surface of the crown ring  33  when the crown ring  33  is in a single state. 
     In this case, the tapping tool can be passed through the crown ring  33  in the axial direction. Accordingly, it is not necessary to take care to subtly control the insertion depth of the tapping tool. Therefore, the machinability with which the internal thread  36  is formed on the crown  31  is improved. In consequence, the internal thread  36  can be machined at low cost. Furthermore, as the machinability is improved in this way, dimensional variations of the internal thread  36  are suppressed, and the machining accuracy can be improved. In addition, a tapping tool is passed through the crown ring  33  during the manufacturing process as described previously to machine the internal thread  36 . Consequently, the internal thread  36  free of incompletely threaded portions, i.e., the internal thread  36  formed from completely threaded portions from the beginning to the end of the threading, can be machined. 
     The crown  31  assembled as shown in  FIGS. 2 and 3  is provided with an annular groove  38  permitting insertion of the barrel outside protruding portion  21   b  between the crown ring  33  and the inside crown shaft  32 . The crown shaft  32  of this crown  31  is inserted inside the stem pipe  21  such that the shaft is movable back and forth in the axial direction. Annular waterproof packing  39  made of a resilient material having resilience such as rubber is mounted in an annular packing installation groove  32   c  (see  FIGS. 4 and 5 ) formed in the outer surface of the crown shaft  32 . The waterproof packing  39  is resiliently deformed into a compressed state between the inner surface of the stem pipe  21  and the outer surface of the crown shaft  32 , thus providing waterproofness between them. 
     The internal thread  36  of the crown  31  is removably threaded to the external thread  23  of the stem pipe  21 . In this case, the internal thread  36  can be more threaded into the external thread  23  by putting a finger on the crown ring  33  of the crown  31  and rotating the crown  31  in the direction to tighten it. Conversely, the threaded engagement can be released by rotating the crown  31  in the direction to loosen it as shown in  FIG. 3 . The end surface of the crown ring  33  is brought into abutment with the barrel outer surface  13   a  of the barrel  13  as shown in  FIG. 2  by rotating the crown  31  to tighten it. Thus, the threadedly locking function is exhibited to prevent inadvertent rotation of the crown  31  during carriage of the wristwatch  11 . 
     As shown in  FIGS. 2 and 3 , a watch stem  41  of the watch movement is slidably inserted in the barrel insertion cylindrical portion  32   a  from inside of the barrel  13  toward the outside, i.e., the watch stem  41  is slidably attached to an inner end portion of the crown shaft  32 . A biasing body such as a coil spring  43  for biasing the crown  31  outwardly of the barrel  13  via a spring receiver  42  while supported by the stem  41  is also accommodated. The watch movement is rotated interlockingly with rotational manipulations of the crown  31  under the condition where the internal thread  36  has been disengaged from the external thread  23  (in other words, the threadedly locking has been released (see  FIG. 3 )) . Consequently, the watch time function can be set. 
     After manipulation of the crown, the crown  31  is mounted to the barrel outside protruding portion  21   b  and threadedly locked. For this purpose, the internal thread  36  of the crown ring  33  is threaded into the external thread  23  of the barrel outside protruding portion  21   b  while being pushed into the stem pipe  21  from outside of the barrel  13  while the stem  41  is kept connected with the crown shaft  32 , and then the internal thread is tightened. The crown ring  33  is abutted against the barrel outer surface  13   a  under the condition where the crown  31  has been most deeply threaded into the external thread  23 . The crown  31  covers and hides the barrel outside protruding portion  21   b.    
     When this wristwatch  11  is being carried, the crown  31  is threadedly locked. Therefore, the displayed time can be prevented from varying due to inadvertent rotation of the crown  31 . When the watch is set, the crown  31  is rotated in the direction opposite to the direction used when threadedly locking is done, disengaging the internal thread  36  from the external thread  23 . The crown  31  is pulled out against the spring force of the coil spring  43 . Under this condition, the setting of the time function can be done. 
     Decrease in the life of the threadedly engaged portion between the internal thread  36  of the crown  31  and the external thread  23  of the stem pipe  21  as the crown is manipulated as described so far can be suppressed for the following reasons. 
     First, as the accuracy at which the internal thread  36  of the crown  31  is machined is improved as described previously, the accuracy at which the internal thread  36  and the external thread  23  of the stem pipe  21  mesh with each other is improved. Therefore, the smoothness of the threaded engagement between the external thread  23  and the internal thread  36  is assured. Damage to the threadedly engaged portion due to defect in the threaded engagement is suppressed. As a result, decrease in the life of the threadedly engaged portion can be suppressed. 
     Secondly, the internal thread  36  of the whole crown  31  is totally made of a completely threaded portion and does not have any incompletely threaded portion as described above. Therefore, as the crown  31  is rotationally manipulated, it is unlikely that the external thread  23  of the stempipe  21  is deformed by an incompletely threaded portion. Hence, decrease in the life of the threadedly engaged portion can be suppressed. 
     Furthermore, the crown ring  33  of the above-described structure forms an outer cylindrical portion of the crown  31 . Since the dimension of the wall thickness between the inner surface consisting of the internal thread  36  of this outer cylindrical portion and the outer surface consisting of an uneven surface can secure a minimum thickness dimension necessary for the crown  31 , the outer diameter of the crown  31  is prevented from increasing with desirable results. Incidentally, a structure is conceivable in which the outer cylindrical portion of the crown is composed of an outer cylindrical portion integral with a crown shaft and an outer cylindrical ring fixed to the inner surface of this portion using an adhesive, and in which an internal thread is machined in the inner surface of this ring. With this structure, however, this outer cylindrical portion needs some extent of thickness to secure mechanical strength for the outer cylindrical portion. In addition, the thickness of the outer cylindrical ring having some degree of thickness permitting machining of the internal thread and the thickness of the adhesive layer are added to this outer cylindrical portion. Therefore, the wall thickness of the outer cylindrical portion of this crown is urged to be increased. This increases the outer diameter of this crown. 
     The present invention is not limited to the above-described one embodiment. The invention can also be applied to wristwatches required to have high-pressure waterproof performance such as divers watches. In addition, the invention can also be applied to watches not required to have such high-pressure waterproof performance such as normal wristwatches, pocket watches, and necklace hanging watches. 
     According to the present invention, a watch can be provided which is capable of improving the life of the threadedly engaging portion between a stem pipe and a crown and which permits easy and accurate machining of an internal thread on the crown, as well as the crown used in this watch.