Patent Publication Number: US-2011051564-A1

Title: Windup portable timepiece and method of operating crown with which this timepiece is equipped

Description:
FIELD OF THE INVENTION 
     The present invention relates to a portable timepiece such as a windup diver&#39;s watch equipped with a crown locked so as to prevent inadvertent rotation while it is being carried about, and a method of operating the crown with which this timepiece is equipped. 
     BACKGROUND OF THE INVENTION 
     There is conventionally known a portable timepiece equipped with a lock structure to prevent inadvertent rotation of a crown through utilization of mesh engagement of gear portions (See, for example, JP-A-2005-127816 (paragraphs 0011-0055 and FIGS. 1 through 5)). 
     In this conventional lock structure, the crown is equipped with a crown shaft interlocked with a winding stem, and a crown head for rotating this shaft. A shaft end portion of the crown shaft is arranged outside a winding stem pipe fixed to a case band containing a movement. At the same time, an odd-form torque receiving portion is formed in the periphery of the shaft end portion, and a crown head is provided with a female screw portion and an odd-form torque transmitting portion. The torque transmitting portion is of a larger diameter than the female screw portion, and is formed so as to be continuous with the female screw portion. The torque transmitting portion is detachable with respect to the torque receiving portion, and the torque transmitting portion and the torque receiving portion constitute a kind of dog clutch serving to effect the transmission of power or the releasing thereof between the crown head and the crown shaft. 
     In this portable timepiece, a male screw portion of the winding stem pipe is situated outside the case band, and the female screw portion of the crown is detachably in mesh with this male screw portion. Through this mesh engagement, there is attained a lock state in which an engagement end surface of the crown is held in contact with a lock surface formed on the outer peripheral portion of the case band, whereby it is possible to maintain the crown free from inadvertent rotation. In the state in which the crown is thus locked, the torque transmitting portion is spaced apart from the torque receiving portion, and the dog clutch is in a state in which the transmission of torque is off. 
     In the state in which the female screw portion and the male screw portion have been placed out of mesh engagement with each other, that is, in the state in which the lock state of the crown has been released, the crown head is moved away from the case band by the urging force of an elastic member. As a result of this movement, the torque transmitting portion is fit-engaged with the torque receiving portion, and the dog clutch is engaged and placed in a state in which the transmission of torque is possible. Thus, when the crown head is rotated with the lock released, rotation is transmitted via the torque transmitting portion and the torque receiving portion fit-engaged with each other to the crown shaft, making it possible to rotate the winding stem. 
     SUMMARY OF THE INVENTION 
     In the portable timepiece of Patent Document 1, when performing the rotating operation to mesh-engage the female screw portion of the crown head with the male screw portion of the pipe to place the crown in the lock state, there is no fear of the winding stem being rotated in synchronization therewith. Thus, in the case of a windup portable timepiece whose movement has a mainspring as the power source thereof, it is advantageously possible to lighten the operation of locking the crown without being affected by the mainspring. 
     However, when releasing the lock state of the crown, between the moment that the mesh engagement of the female screw portion and the male screw portion is released and the moment that the torque transmitting portion is engaged with the torque receiving portion, the crown head is not supported, and there is a possibility of its becoming loose. Thus, the operation of the crown becomes rather unstable, and the torque transmitting portion may be incapable of being smoothly engaged with the torque receiving portion. That is, in some cases, it is impossible to attain satisfactory operability in placing the dog clutch composed of the torque transmitting portion and the torque receiving portion in the “engaged (connected)” state. 
     Further, in Patent Document 1, there is no description regarding the rotating direction of the crown when the mainspring is wound up, and the rotating direction of the crown when the lock state is released. Generally speaking, however, the winding-up of the mainspring is effected by rotating the crown to the right (clockwise). On the other hand, to release the engagement of the male screw portion and the female screw portion, the crown is rotated to the left (counterclockwise). 
     Thus, to release the lock state of the crown, and then wind up the mainspring, it is necessary to first rotate the crown to the left to release the lock state of the crown, and then rotate the crown to the right to wind up the mainspring. In these procedures, it is necessary to check as to whether the lock of the crown has been released or not; further, based on this checking, the crown is rotated in the reverse direction, so that it is impossible to perform the series of procedures from the releasing of the lock state of the crown to the winding-up of the mainspring through an operation similar to a one-stroke operation, resulting in a rather poor operability. 
     It is an object of the present invention to provide a windup portable timepiece in which it is possible to improve the operability of the crown when placing the crown in a lock state and when releasing the lock state of the crown to wind up the mainspring, and a method of operating the crown with which this timepiece is equipped. 
     To solve the above problem, there is provided, according to the present invention, a portable timepiece comprising: a movement having a mainspring, and a one-way clutch which transmits rotation to wind up this mainspring to the mainspring and which operates so as to prevent rotation to rewind the mainspring from being transmitted to the mainspring; a winding stem transmitting rotation to this movement; a timepiece exterior assembly having a case band with a lock surface formed in an outer peripheral portion thereof and containing the movement and the winding stem; a winding stem pipe having a male screw portion arranged outside the case band and fixed to the case band; and a crown which has a crown head arranged outside the case band, the crown head having a female screw portion detachably and threadedly engaged with the male screw portion and an engagement end surface moving toward and away from the lock surface, and which is rotated in a direction opposite to the direction in which the mainspring is wound up when bringing the engagement end surface into contact with the lock surface to maintain a lock state, and is rotated in the same direction as the direction in which the mainspring is wound up when releasing the lock state and winding up the mainspring. 
     In the present invention, although no dog clutch is provided in the crown, when placing the crown in the lock state, a state is attained in which the one-way clutch of the movement cuts off power transmission as the crown is rotated in a direction opposite to the direction in which the crown is rotated when winding up the mainspring. Thus, it is possible to place the crown in the lock state without receiving the winding-up load of the mainspring, and, if, at this time, the mainspring has been wound up, there is no fear of this mainspring being further wound up, so that the rotation of the crown when placing the crown in the lock state does not become heavy. Further, when the lock state of the crown is released and the mainspring is wound up, the direction in which the crown is rotated to release the lock state of the crown and the direction in which the crown is rotated to subsequently wind up the mainspring, are the same. Thus, it is possible to attain continuity in the rotating operation without having to mind the rotating direction of the crown, thereby making it possible to improve the operability of the crown. 
     A preferred mode of the portable timepiece of the present invention is characterized in that the male screw portion and the female screw portion are formed such that when the crown is rotated in a direction opposite to the direction in which the mainspring is wound up, the crown is moved so as to bring the engagement end surface into contact with the lock surface. 
     In this preferred mode, the male screw portion of the winding stem pipe and the female screw portion of the crown are held in mesh with each other, and the crown is rotated in a direction opposite to the direction in which the mainspring is wound up, whereby the crown is moved to the case band side and the engagement end surface thereof is brought into contact with the lock surface of the case band, thereby maintaining the crown in the lock state. At the same time, when the lock state is released and the mainspring is wound up, the crown is rotated in the same direction as the winding-up direction of the mainspring, so that, by forming the male screw portion and the female screw portion in conformity with the mainspring winding-up direction of the movement, it is possible to solve the problem of the present invention while adopting the same construction as that of the prior art for the remaining portions. 
     A preferred mode of the portable timepiece of the present invention is characterized in that the mainspring is wound up when the crown is rotated to the right, and that the crown is arranged in the lock state when the crown is rotated to the left. 
     In this preferred mode, to wind up the mainspring, the crown is rotated to the right, i.e., in the same crown rotating direction as generally adopted in the prior art, so that no sense of incongruity is involved in the operation of winding up the mainspring. At the same time, the lock state of the crown can be realized by rotating the crown to the left, so that, by forming the male screw portion and the female screw portion so as to enable them to rotate to the right and to the left, it is possible to solve the problem of the present invention while adopting the same construction as that of the prior art for the remaining portions. 
     A preferred mode of the portable timepiece of the present invention is characterized in that a sign indicating the rotating direction of the crown when placing the crown in the lock state is provided on a front side of a crown head. 
     In this preferred mode, by rotating the crown according to the sign on the crown head, it is possible to suppress an error in the crown rotating direction in placing the crown in the lock state. 
     In the method of operating the crown with which the portable timepiece of the present invention is equipped, there is adopted as a prerequisite a portable timepiece comprising: a movement having a mainspring, and a one-way clutch which transmits rotation to windup this mainspring to the mainspring and which operates so as to prevent rotation to rewind the mainspring from being transmitted to the mainspring; a winding stem transmitting rotation to this movement; a timepiece exterior assembly having a case band with a lock surface formed in an outer peripheral portion thereof and containing the winding stem; a winding stem pipe having a male screw portion arranged outside the case band and fixed to the case band; and a crown which has a crown head arranged outside the case band and having a female screw portion detachably and threadedly engaged with the male screw portion and an engagement end surface moving toward and away from the lock surface, and which is maintained in a lock state by bringing the engagement end surface into contact with the lock surface. 
     And, to solve the above problem, there is provided, according to the present invention, a method of operating a crown characterized in that, when placing the crown in the lock state, the crown is rotated in a direction opposite to the direction in which the mainspring is wound up, and that, when winding up the mainspring from the lock state, the crown is rotated in the same direction as the winding-up direction of the mainspring to release the lock, and continue, subsequent to this releasing, the rotation of the crown in the same direction. 
     In this crown operating method, in the operation of rotating the crown when placing the crown in the lock state, the one-way clutch cuts off power transmission as the crown is rotated in a direction opposite to the crown rotating direction when winding up the mainspring, so that it is possible to lock the crown without receiving the winding-up load of the mainspring; further, at this time, even if the mainspring has been wound up, there is no fear of this mainspring being further wound up, so that the crown rotating operation when locking the crown does not become heavy, thereby improving the operability of the crown. Further, when releasing the lock state of the crown and winding up the mainspring, the rotating direction of the crown when releasing the lock of the crown and the rotating direction for the subsequent winding-up of the mainspring are the same, and it is possible to achieve continuity in the rotating operation without having to mind the rotating direction of the crown, so that it is possible to improve the operability of the crown. 
     According to the present invention, it is possible to improve the operability of the crown when placing the crown in the lock state and when releasing the lock state of the crown to wind up the mainspring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a windup wristwatch according to an embodiment of the present invention with the crown thereof locked. 
         FIG. 2  is a sectional view taken along the line F 2 -F 2  of  FIG. 1 . 
         FIG. 3  is a front view of a wristwatch according to an embodiment with the lock of the crown thereof released. 
         FIG. 4  is a sectional view taken along the line F 4 -F 4  of  FIG. 3 . 
         FIG. 5  is a side view of the portion of a wristwatch according to an embodiment around the crown thereof. 
         FIG. 6  is a perspective view showing a part of a movement with which a wristwatch according to an embodiment is equipped along with a winding stem. 
         FIG. 7  is a perspective view showing the portion of a movement with which a wristwatch according to an embodiment is equipped around a one-way clutch thereof. 
         FIG. 8  is a diagram showing the relationship between a movement barrel of a movement with which a wristwatch according to an embodiment is equipped and a mainspring accommodated therein prior to the winding-up of the mainspring. 
         FIG. 9  is a diagram showing the relationship between a movement barrel of a movement with which a wristwatch according to an embodiment is equipped and a mainspring accommodated therein with the mainspring wound up. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, an embodiment of the present invention will be described in detail with reference to  FIGS. 1 through 9 . 
     In  FIGS. 1 through 4 , numeral  10  indicates a windup portable timepiece such as a windup wristwatch. As shown in  FIGS. 2 and 4 , a timepiece exterior assembly  11  of the wristwatch  10  contains a time indication plate  12  and a movement  13 , and, as shown in  FIGS. 1 through 4 , a crown  35  is mounted to the peripheral portion of the timepiece exterior assembly  11 . 
     As shown in  FIGS. 2 and 4 , the timepiece exterior assembly  11  is equipped with a case band  14 , a cover glass  16 , and a case back  18 . The case band  14  is formed of metal in an annular configuration. The case band  14  has a glass support member  14   a  attached to the front side thereof. The glass support member  14   a  is formed of metal in an annular configuration. Instead of being formed as separate members as described above, the glass support member  14   a,  and the portion of the case band  14  other than that, that is, the case band main portion, may also be formed integrally. 
     A groove  14   b  is formed in the outer peripheral portion of the case band  14 , more specifically, in the outer peripheral portion of the case band main portion. The groove  14   b  is provided in correspondence with the time indication of  3  o&#39;clock on the time indication plate  12 , and is open on the front side, on the back side, and sideways in the timepiece exterior assembly  11 . The case band  14  has a lock surface  14   c  parallel to the thickness direction thereof, and the lock surface  14   c  is formed by the bottom surface of the groove  14   b.    
     The peripheral portion of the cover glass  16  is connected to the glass support member  14   a  in a liquid-tight fashion; it is attached thereto so as to cover the front side consisting of one surface in the thickness direction of the case band  14 . The case back  18  is formed of metal or the like, and is threadedly attached to the case band  14  while covering in a liquid-tight fashion the back surface consisting of the other surface in the thickness direction of the case band  14 . 
     The portion of the case band  14  other than the glass support member  14   a,  that is, the case band main portion, has a pipe mounting hole  15  extending radially through the case band  14 . One end of the pipe mounting hole  15  is open to an in-case-band space  14 d surrounded by the case band  14 . The other end of the pipe mounting hole  15  is open to the lock surface  14   c.    
     The movement  13  arranged in the in-case-band space  14 d is of a mechanical type using as a power source a mainspring  28  (See  FIGS. 8 and 9 ) wound up through manual operation of the crown  35 . The movement  13  is, for example, of a general conventional type; as shown in  FIG. 6 , to wind up the mainspring  28 , it is equipped with a clutch wheel  20 , a winding pinion  21 , a one-way clutch  22 , a crown wheel  23 , a crown operating wheel  24 , a rock wheel  25 , a ratchet wheel  26 , a movement barrel  27 , etc. 
     The clutch wheel  20  is connected to a winding stem  45  described below. The clutch wheel  20  has a square shaft portion (not shown), and this square shaft portion is inserted for connection into a square hole (not shown) of the winding stem  45 . Thus, the clutch wheel  20  is rotated in synchronization with the rotation of the winding stem  45 , and the winding stem  45  can move in the axial direction along the square shaft portion of the clutch wheel  20 ; through this movement, the winding stem  45  and the crown  35  are moved to the positions of “0th step,” “1st step,” and “2nd step.” At the position of the “1st step, ” the power transmission between the clutch wheel  20  and the winding pinion  21  is released, and the clutch wheel is connected to a calendar corrector wheel row (not shown); at the position of the “2nd step, ” it is connected to a time corrector wheel row (not shown). 
     The outer periphery of the clutch wheel side end portion of the winding stem  45  is formed in a round configuration, and the winding pinion  21  is fit-engaged with this outer periphery so as to be rotatable and incapable of moving in the axial direction of the winding stem  45 . The one-way clutch  22  serves to effect and release the power transmission between the clutch wheel  20  and the winding pinion  21 ; for example, as shown in  FIG. 7 , there is employed a dog clutch equipped with a pair of clutch members  22   a,    22   b  having a plurality of claw portions with inclined surfaces. The clutch member  22   a  is formed integrally with the clutch wheel  20 , and the clutch member  22   b  is formed integrally with the winding pinion  21  moved together with the winding stem  45 . When the winding stem  45  is rotated to the right (clockwise), the one-way clutch  22  maintains the engagement of the clutch members  22   a,    22   b,  and transmits power from the clutch wheel  20  to the winding pinion  21 . Conversely, when the winding pinion  45  is rotated to the left (counterclockwise), the one-way clutch  22  releases the engagement of the clutch members  22   a,    22   b,  releasing the transmission of power from the clutch wheel  20  to the winding pinion  21 . 
     As shown in  FIG. 6 , the crown wheel  23  is arranged so as to be perpendicular to the winding pinion  21 , and is in mesh with the winding pinion  21 . The crown operating wheel  24  is in mesh with the crown wheel  23 , and the rock wheel  25  is in mesh with the crown operating wheel  24 . Further, the ratchet wheel  26  is in mesh with the rock wheel  25 . The ratchet wheel  26  is provided on a side surface of the movement barrel  27 . Thus, when the rotation of the winding stem  45  is transmitted to the winding pinion  21 , the movement barrel  27  is rotated via the wheel row formed by the crown wheel  23 , the crown operating wheel  24 , the rock wheel  25 , and the ratchet wheel  26 . 
     As shown in  FIGS. 8 and 9 , a mainspring  28  is accommodated in the movement barrel  27 . Portion A of a winding-end end portion  28   a  of the mainspring  28  is welded to a mainspring catch piece member  29 . The mainspring catch piece member  29  is caught by a groove  27   a  open to the peripheral wall inner surface of the movement barrel  27 . A winding-start end portion  28   b  of the mainspring  28  is fixed at the center of the movement barrel  27 . The mainspring  28  is constructed such that when the crown  35  described below is rotated, for example, to the right (clockwise), the movement barrel  27  is rotated to the right to thereby wind up the mainspring.  FIG. 9  shows a state in which the mainspring  28  has been wound up, and  FIG. 8  shows a state in which the mainspring  28  has been rewound. The movement  13  is driven by the force with which the mainspring  28  is rewound. 
     As shown in  FIGS. 2 and 4 , a metal winding stem pipe  31  is mounted to the case band  14 . The winding stem pipe  31  is inserted into the pipe mounting hole  15  from the outside of the case band  14 , and brazed to the case band  14 . The winding stem pipe  31  is formed as a cylinder whose axial ends are open, and is equipped with a pipe end portion  31   a  arranged outside the case band  14 . The pipe end portion  31   a  protrudes sidewise perpendicularly with respect to the lock surface  14   c.    
     The pipe end portion  31   a  has on the outer peripheral portion thereof a male screw portion  32 . The male screw portion  32  is formed by a screw portion having a thread ridge wound in a direction opposite to the winding-up direction of the mainspring  28  so that the one-way clutch  22  may be disengaged (the power transmission may be cut off) with the rotation of the crown  35  to place the crown  35  described below in the lock state. Further, the male screw portion  32  is formed such that when the crown  35  described below is rotated in a direction opposite to the winding-up direction of the mainspring  28 , the crown  35  is moved so as to bring an engagement end surface  37   a  described below into contact with the lock surface  14   c.  Thus, in this embodiment, the male screw portion  32  is formed, for example, by a left-handed screw. 
     The metal crown  35  has a crown shaft  36 , and a crown head  37  formed by an integral protrusion extending from the central portion of the crown shaft  36 . The crown shaft  36  is formed as a round pipe whose forward end is open. Annular waterproof packing  38  formed of an elastic material such as rubber or elastomer is attached to the outer periphery of the forward end portion of the crown shaft  36 . Further, a connection ring  39  is fixed to the inner side of the forward end portion of the crown shaft  36 . The center hole of the connection ring  39  is a square hole. 
     The crown head  37  is shorter and of a larger diameter than the crown shaft  36 , and a round clearance groove  41  surrounding the outer periphery of the proximal portion of the crown shaft  36  is formed between them. A pipe end portion  31   a  can be inserted and extracted into and from the clearance groove  41  as the crown  35  is attached and detached to and from the winding stem pipe  31 . The crown head  37  has a round engagement end surface  37   a  continuous with the open end of the clearance groove  41 . The engagement end surface  37   a  is parallel to a plane orthogonal to the axial direction of the crown shaft  36 . An outer peripheral surface  37   b  of the crown head  37  is formed as a knurled asperity surface so that the fingers of the user turning the crown  35  may not be easily allowed to slip thereon. 
     Further, the crown head  37  has in the inner peripheral portion thereof a female screw portion  42  detachably and threadedly engaged with the male screw portion  32  of the winding stem pipe  31 . Like the male screw portion  32 , the female screw portion  42  is formed by a screw portion having a thread ridge wound in a direction opposite to the winding-up direction of the mainspring  28  so that the one-way clutch  22  may be disengaged with the rotation of the crown  35  when placing the crown  35  in the lock state. Further, the female screw portion  42  is formed such that when the crown  35  described below is rotated in a direction opposite to the winding-up direction of the mainspring  28 , the crown  35  is moved so as to bring the engagement end surface  37   a  described below into contact with the lock surface  14   c.  Thus, in this embodiment, as in the case, for example, of the male screw portion  32 , the female screw portion  42  is formed as a left-handed screw. 
     As shown in  FIG. 5 , a sign  40  is provided on the front surface of the crown head  37 . The sign  40  indicates the rotating direction of the crown  35  when placing the crown  35  in the lock state; it consists of an arrow and a row of characters such as “LOCK.” 
     The crown shaft  36  of the crown  35  is inserted into the winding stem pipe  31  from the outside of the case band  14 . Waterproof packing  38  for waterproofness with respect to the in-case-band space  14   d  is slidalby held in contact with the inner peripheral surface of the winding stem pipe  31 . At the same time, the female screw portion  42  of the crown  35  is threadedly engaged with the male screw portion  32  of the winding stem pipe  31 , and the crown  35  is detachably mounted to the winding stem pipe  31 . 
     The metal winding stem  45  for transmitting the rotation of the crown  35  or the like to the movement  13  is connected to the crown  35 . That is, one end portion of the winding stem  45  arranged inside the in-case-band space  14   d  is connected to the movement  13 , and the other end portion of the winding stem  45  arranged on the crown  35  side is inserted into the crown shaft  36  through a forward end opening thereof. The other end portion of the winding stem  45  is of a square-shaft configuration (not shown) corresponding to the central hole of the connection ring  39 , and this square-shaft-shaped portion is slidably inserted into the central hole. Through fit-engagement between the central hole and the other end portion (square-shaft-shaped portion) of the winding stem  45 , the rotation of the crown  35  is transmitted to the winding stem  45 . 
     Further, a snap ring  46  arranged inside the crown shaft  36  is mounted to the other end portion of the winding stem  45 . The snap ring  46  is held so as to be incapable of moving in the axial direction of the winding stem  45 . A coil spring  47  using the snap ring  46  as a spring shoe is accommodated in the crown shaft  36 , and the crown  35  is urged away from the lock surface  14   c  of the case band  14  by the spring force of this coil spring  47 . 
       FIG. 2  shows a state in which the crown  35  is locked so as not to inadvertently rotate in the wristwatch  10  constructed as described above. In this lock state, the female screw portion  42  of the crown  35  is in mesh (threadedly engaged) with the male screw portion  32  of the winding stem pipe  31 , and the engagement end surface  37   a  of the crown  35  is held in contact with the lock surface  14   c  of the case band  14 . Thus, using the lock surface  14   c  as a stopper, positioning is effected on the crown  35  such that it cannot be further rotated in the direction indicated by the sign  40 . 
     In this lock state, with the insertion depth of the crown shaft  36  with respect to the winding stem pipe  31  being maximum, the coil spring  47  is in a firmly compressed state, and the crown  35  is strongly urged away from the case band  14 . In spite of this, the crown  35  is not moved away from the case band  14  through the above-mentioned mesh engagement. 
     When releasing the lock state of the crown  35 , it is only necessary to rotate the crown  35  to the right (clockwise). As a result, the state of engagement between the male screw portion  32  and the female screw portion  42  is changed, and the crown  35  is moved such that the engagement end surface  37   a  is moved away from the lock surface  14   c  of the case band  14 , so that the lock state is released, and, soon, the mesh engagement of the female screw portion  42  with the male screw portion  32  is released. At the same time, due to the spring force of the coil spring  47 , the crown  35  is pushed out until the connection ring  39  abuts the snap ring  46 .  FIGS. 3 and 4  show this lock-released state. 
     As described above, with the lock being released and the crown  35  pushed out, that is, in the “0th step” state, the crown  35  is continuously rotated to the right (clockwise), whereby it is possible to wind up the mainspring  28  of the movement  13 . In this case, the crown  35  is rotated such that the one-way clutch  22  of the movement  13  is “engaged,” or, in other words, placed in the connected state, so that the rotation of the crown  35  is transmitted to the movement  13  via the winding stem  45 , and the mainspring  28  is wound up. 
     As described above, the rotating direction of the crown  35  when releasing the lock state of the crown  35  and the rotating direction of the crown  35  when winding up the mainspring  28  subsequent thereto are the same. Thus, when releasing the lock state of the crown  35  and winding up the mainspring  28 , there is no need to check whether the lock state of the crown  35  has been released or not, and there is no need to take the trouble to rotate the crown  35  in the reverse direction based on this checking. 
     That is, through the easy operation of simply continuing the rotation to release the lock state of the crown  35  even after the lock state has been released, it is possible to successively perform the releasing of the lock state of the crown  35  and the winding-up of the mainspring  28  without having to mind the rotating direction, etc. of the crown  35 . When thus releasing the lock state of the crown  35  and winding up the mainspring  28 , the rotating direction of the crown  35  remains the same, and it is only necessary to continuously rotate the crown  35 , so that it is possible to improve the operability of the crown  35 . It is possible to perceive the completion of the winding-up of the mainspring  28  as the rotation of the crown  35  becomes heavier due to the load of the mainspring  28  abruptly increased through the winding-up of the mainspring  28 . 
     Further, when performing date setting in the state of  FIGS. 3 and 4 , in which the winding-up of the mainspring  28  is possible, the crown  35  is pulled further away from the lock surface  14   c,  and is arranged at the date setting position, that is, the “1st step” position, and then the crown  35  is rotated. Further, when performing time setting, the crown  35  is further pulled from the “1st step” position to the time setting position, that is, the “2nd step” position, and then the crown  35  is rotated, thereby making it possible to effect time setting. 
     When the crown  35  is arranged at one of these two positions, the engagement of the one-way clutch  22  is released (in other words, the one-way clutch  22  is disengaged), so that the mainspring  28  does not constitute a load in rotating the crown  35  for date setting or time setting. 
     To restore the crown  35  to the lock state after each of the above operations, the crown  35  is pushed back toward the case band  14  side against the coil spring  47 , and then the crown  35  is rotated to threadedly engage the female screw portion  42  thereof with the male screw portion  32  of the winding stem pipe  31 . In this case, the crown  35  is rotated according to the sign  40  of the crown head  37 . As a result, in placing the crown  35  in the lock state, it is possible to suppress an error in the rotating direction of the crown  35 . 
     When restoring the crown  35  to the lock state by the above procedures, the crown  35  is rotated in a direction opposite to the winding-up direction of the mainspring  28 . More specifically, the crown  35  is rotated to the left. Through the resultant change in the mesh engagement between the female screw portion  42  and the male screw portion  32 , the crown  35  is moved toward the lock surface  14   c  of the case band  14 , and, soon, the engagement end surface  37   a  of the crown  35  abuts the lock surface  14   c.  Thus, through this contact, it is possible to maintain the crown  35  in the lock state so that the crown  35  may not be unnecessarily rotated while, for example, the wristwatch  10  is being carried about. 
     When thus placing the crown  35  in the lock state, the crown  35  is rotated, as described above, in a direction opposite to the winding-up direction of the mainspring  28 , and, at the same time, the winding stem  45  is rotated in the same direction as the crown  35 . The rotating direction of the winding stem  45  at this time is such that the one-way clutch  22  is placed in the “disengaged” state, so that the driving side clutch member  22   a  of the one-way clutch  22  idles on the receiving side clutch member  22   b  so as to slip thereon. As a result, the rotation of the crown  35  rotated to the left so as to rewind the mainspring  28  is not transmitted to the winding pinion  21  via the one-way clutch  22 . 
     When thus placing the crown  35  in the lock state, the crown  35  and the mainspring  28  are not connected to each other via the winding stem  45  and the one-way clutch  22 , so that the mainspring  28  does not constitute a load with respect to the rotation of the crown  35 . Thus, even in the state in which the mainspring  28  has been sufficiently wound up, the rotating operation of the crown  35  when placing the crown  35  in the lock state does not become heavier due to the mainspring  28 . In this way, it is possible to attain the lock state through rotation of the crown  35  without receiving the winding-up load of the mainspring  28 , so that it is possible to improve the operability of the crown  35 . 
     Further, in the portable timepiece  10  constructed as described above, by utilizing the one-way clutch  22  of the movement  13  as described above, it is possible to perform the rotation of the crown  35  when placing the crown  35  without receiving the winding-up load of the mainspring  28 . Thus, there is no need to provide a dedicated clutch for preventing reception of the winding-up load of the mainspring  28  when maintaining the lock state through rotation of the crown  35 . That is, there is no need, as in the prior art, to contrive to divide the crown into the crown head and the crown shaft and to provide therebetween a dog clutch on the inner side of the crown head  37 , and the crown shaft  36  and the crown head  37  can be integrated to form the crown  35 , so that it is possible to achieve a simple construction for the crown  35  and to prevent an increase in the thickness of the crown head  37  of the crown  35 . 
     Further, in this embodiment, the mainspring  28  is wound up when the crown  35  is rotated to the right, and the crown  35  is arranged in the lock state when the crown  35  is rotated to the left. Thus, to wind up the mainspring  28 , the crown  35  is rotated to the right in the same crown rotating direction as in an ordinary windup portable timepiece, so that there is involved no sense of incongruity in the operation of winding up the mainspring  28 . At the same time, the lock state of the crown  35  can be realized by rotating the crown  35  to the left. Thus, by forming the male screw portion  32  and the female screw portion  42  so as to enable such rotating operation, the construction of the other portions such as the movement  13  may be the same as that in the prior art, which means the embodiment can be easily carried out. 
     In the above embodiment, when the crown  35  is rotated to the right, the lock state of the crown  35  is released, and the mainspring  28  is wound up; conversely, when the crown  35  is rotated to the left, the crown  35  is threadedly engaged in the lock state, and the one-way clutch  22  is disengaged so that the rotation of the crown  35  may not be transmitted to the mainspring  28 ; however, it is also possible for the present invention to be carried out in a fashion reverse to the above. That is, the present invention can also be carried out through a construction in which when the crown  35  is rotated to the left, the lock state of the crown  35  is released, and the mainspring  28  is wound up; when, conversely, the crown  35  is rotated to the right, the crown  35  is threadedly engaged in the lock state, and the one-way clutch  22  is disengaged so that the rotation of the crown  35  may not be transmitted to the mainspring  28 . 
     The present invention can also be applied to a portable timepiece other than a wristwatch, for example, a pocket watch.