Patent Publication Number: US-11022940-B2

Title: Timepiece movement and timepiece

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a timepiece movement and a timepiece. 
     2. Related Art 
     Timepieces that have a 24-hour hand in addition to an hour hand, minute hand, and secondhand are known from the literature. See, for example, JP-A-2016-57269. 
     In the timepiece described in JP-A-2016-57269, the hour hand, minute hand, second hand, and 24-hour hand are attached to coaxially disposed arbors. The second hand arbor to which the second hand is disposed is guided on the outside by a tubular center wheel and pinion. The center wheel and pinion is guided by a second bridge and main plate, and the minute hand arbor (cannon pinion), to which the minute hand is attached, is attached to the center wheel and pinion. The hour hand arbor is guided on the inside by the minute hand arbor, and is guided on the outside by a tubular center pipe. The 24-hour arbor to which the 24-hour hand is attached is guided on the inside by the center pipe. 
     However, when the individual arbors turn in the timepiece configuration described in JP-A-2016-57269, the second hand arbor and minute hand arbor, and the minute hand arbor and the hour hand arbor, may contact each other. There is also backlash in the wheels turning the minute hand arbor and hour hand arbor. 
     As a result, when the second hand arbor and minute hand arbor are in contact, rotation of the second hand arbor, which turns faster than the minute hand arbor, may cause the minute hand arbor to turn. In addition, when the minute hand arbor and hour hand arbor are touching, rotation of the minute hand arbor, which turns faster than the hour hand arbor, may cause the hour hand arbor to turn. 
     Lubricant may also be injected between the arbors to reduce friction and wear. In this case, even if the second hand arbor and minute hand arbor are not touching, the viscosity of the lubricant may cause the minute hand arbor to turn when the second hand arbor turns. Likewise, even if the minute hand arbor and hour hand arbor are not touching, the viscosity of the lubricant may cause the hour hand arbor to turn when the minute hand arbor turns. 
     When gravity works in the opposite direction as the direction of rotation of the minute hand arbor and hour hand arbor, the minute hand arbor and hour hand arbor turned by the rotation of the second hand arbor and minute hand arbor, respectively, backlash may be caused by the weight of each arbor in the opposite direction as the direction of rotation. In this case, the minute hand and hour hand may waver, and give the user the impression of low precision. 
     SUMMARY 
     An object of the present invention is to provide a timepiece movement and a timepiece able to one arbor from turning in conjunction with rotation of another arbor. 
     A timepiece movement according to a preferred aspect of the invention has: a second hand wheel with a second hand arbor to which a second hand attaches; a minute hand wheel with a minute hand arbor to which a minute hand attaches; an hour hand wheel with an hour hand arbor to which an hour hand attaches; a 24-hour hand wheel with a 24-hour hand arbor to which a 24-hour hand attaches; and a first guide, a second guide, and a third guide each configured to guide an arbor to which a hand attaches. The minute hand arbor, the hour hand arbor, and the 24-hour hand arbor have a tubular configuration and are disposed coaxially to the second hand arbor. The minute hand arbor has a diameter greater than the secondhand arbor, the hour hand arbor has a diameter greater than the minute hand arbor, and the 24-hour hand arbor has a diameter greater than the hour hand arbor. The first guide is disposed between the second hand arbor and the minute hand arbor, the second guide is disposed between the minute hand arbor and the hour hand arbor, and the third guide is disposed between the hour hand arbor and the 24-hour hand arbor. 
     Because the first guide is disposed between the secondhand arbor and minute hand arbor in this configuration, contact between the second hand arbor and minute hand arbor can be suppressed, and rotation of the minute hand arbor in conjunction with rotation of the second hand arbor can be suppressed. Rotation of the minute hand arbor in conjunction with rotation of the second hand arbor due to the lubricant can also be suppressed. 
     Furthermore, because the second guide is disposed between the minute hand arbor and hour hand arbor, this configuration can suppress contact between the minute hand arbor and the hour hand arbor, and can suppress rotation of the hour hand arbor in conjunction with rotation of the minute hand arbor. Rotation of the hour hand arbor in conjunction with rotation of the minute hand arbor due to the lubricant can also be suppressed. 
     Furthermore, because the third guide is disposed between the hour hand arbor and the 24-hour hand arbor, this configuration can suppress contact between the hour hand arbor and the 24-hour hand arbor, and can suppress rotation of the 24-hour hand arbor in conjunction with rotation of the hour hand arbor. Rotation of the 24-hour hand arbor in conjunction with rotation of the hour hand arbor due to the lubricant can also be suppressed. 
     This configuration of the invention can therefore suppress rotation of one arbor or pivot in conjunction with rotation of another arbor or pivot. 
     The timepiece movement preferably also has a date indicator, and a date indicator bridge holding the date indicator. The third guide is configured by part of the date indicator bridge. 
     Because the third guide in this configuration is configured by part of the date indicator bridge, there is no need for another part embodying the third guide, and the parts count can be reduced. 
     The timepiece movement preferably also has an hour hand ring, and the hour hand ring is disposed between the hour hand wheel and the date indicator bridge. 
     Because the third guide disposed between the hour hand arbor and the 24-hour hand arbor is configured by part of the date indicator bridge, the date indicator bridge can be located near the hour hand wheel, and the hour hand ring can be disposed between the hour hand wheel and the date indicator bridge. The hour hand ring in this configuration can therefore limit movement of the hour hand wheel in the axial direction. 
     In a timepiece movement according to another aspect of the invention, at least part of the part of the second guide that guides the hour hand arbor, and the part where the hour hand arbor and the hour hand ring contact, are on a same plane perpendicular to an axial direction. 
     This configuration can prevent the hour hand wheel from tilting, and the hour hand ring can limit movement of the hour hand wheel in the axial direction. 
     A timepiece movement according to another aspect of the invention preferably also has a minute wheel bridge; and the first guide is disposed to the minute wheel bridge. 
     This configuration does not require a separate member to hold the first guide, and the parts count can therefore be reduced. 
     A timepiece movement according to another aspect of the invention preferably also has a wheel train bridge superimposed in the axial direction on the minute wheel bridge; and the second hand arbor is guided by the wheel train bridge and the first guide. 
     Because the second hand arbor in this configuration is guided by a first guide disposed to the minute wheel bridge, the second hand arbor can be guided without the second hand wheel tilting. 
     A timepiece movement according to another aspect of the invention preferably also has a main plate; and the second guide is disposed to the main plate. 
     This configuration does not require a separate member to hold the second guide, and the parts count can therefore be reduced. 
     Another aspect of the invention is a timepiece including the timepiece movement described above; a dial; and a 24-hour hand ring; and the 24-hour hand ring is disposed between the 24-hour hand wheel and the dial. 
     This configuration can limit movement of the 24-hour wheel in the axial direction by the 24-hour hand ring. 
     Preferably in a timepiece according to another aspect of the invention, at least part of the part of the third guide that guides the 24-hour arbor, and the part where the 24-hour hand wheel and the 24-hour hand ring contact, are on a same plane perpendicular to an axial direction. 
     The 24-hour hand ring in this configuration can limit movement of the 24-hour wheel in the axial direction while also suppressing tilting of the 24-hour hand wheel. 
     Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a timepiece according to the invention. 
         FIG. 2  is a section view of the movement according to a preferred embodiment of the invention. 
         FIG. 3  is a section view of the movement according to a preferred embodiment of the invention. 
         FIG. 4  is an enlarged view of part of  FIG. 3 . 
         FIG. 5  is an oblique view of the hour wheel (not including the hour wheel body) according to a preferred embodiment of the invention. 
         FIG. 6  is a plan view of the movement according to a preferred embodiment of the invention. 
         FIG. 7  is a plan view of the movement (not including the date indicator) according to a preferred embodiment of the invention. 
         FIG. 8  is an oblique view of the date change mechanism from the face side of the timepiece according to a preferred embodiment of the invention. 
         FIG. 9  is an oblique view of the date change mechanism from the back cover side of the timepiece according to a preferred embodiment of the invention. 
         FIG. 10  illustrates the date change operation of a preferred embodiment of the invention. 
         FIG. 11  illustrates the date change operation of a preferred embodiment of the invention. 
         FIG. 12  is a graph of the load torque of the hour wheel body according to a preferred embodiment of the invention. 
         FIG. 13  illustrates the date change operation in another embodiment of the invention. 
         FIG. 14  illustrates the date change operation in another embodiment of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A preferred embodiment of the present invention is described below with reference to the accompanying figures. 
     Timepiece Configuration 
       FIG. 1  is a plan view of an electronic timepiece  1  according to the invention. 
     The timepiece  1  has a round external case  11 , and a round dial  12  disposed inside the external case  11 . Of the two open sides of the external case  11 , the opening on the face side of the timepiece (referred to below as simply the face side) is closed by a crystal  14  held by a round bezel  13 , and the opening on the back side of the timepiece (referred to below as simply the back side) is closed by a back cover not shown. The external case  11  and back cover embody the case of the timepiece  1 . 
     Inside the case the timepiece  1  also includes a movement  2  (see  FIG. 2 ,  FIG. 3 ), second hand  21 , minute hand  22 , hour hand  23 , 24-hour hand  24 , and date indicator  25  as a calendar wheel. The hands  21  to  24  are attached to coaxially disposed arbors (pivots)  411 ,  421 ,  741 ,  451  (see  FIG. 4 ) that are included in the movement  2  and driven by the movement  2 . 
     By the 24-hour hand  24  pointing to a 24-hour marker disposed to the bezel  13 , this timepiece  1  can indicate the hour of a time in a different time zone than the time zone of the time indicated by the hour hand  23 . For example, when travelling to a foreign country, the hour of the local time in the current time zone may be indicated by the hour hand  23  while the hour of the time in Japan is indicated by the 24-hour hand  24 . 
     The dial  12  also has a date window  12 A, and numbers on the date indicator  25  can be seen through the date window  12 A. The numbers on the date indicator  25  indicate the day value of the year-month-day date. 
     On the side of the external case  11  is disposed a crown  15 , which is attached to the winding stem  39  (see  FIG. 6 ) of the movement  2  and is operated to adjust the time and date. 
     Configuration of the Movement 
       FIG. 2  and  FIG. 3  are section views of the movement  2 , and  FIG. 4  is an enlarged view of part of  FIG. 2 . 
     As shown in  FIG. 2  and  FIG. 3 , the movement  2 , which is a timepiece movement, has in order from the dial  12  to the back cover, a calendar plate  31 , main plate  32 , center wheel bridge  33  (minute wheel bridge), and wheel train bridge  34 . 
     The winding stem  39  to which the crown  15  is attached is also incorporated in the movement  2 . The winding stem  39  can be pulled out in the axial direction to two stops from the zero stop position (the position when pushed all the way in). 
     The movement  2  also includes a wheel train mechanism  40  for indicating the time (hour, minute, second), a date change mechanism  50  for displaying the date, and a time difference correction mechanism  60  for adjusting the time difference of the hour hand  23 . 
     Configuration of the Wheel Train Mechanism 
     The wheel train mechanism  40  includes a fifth wheel (not shown in the figure), fourth wheel and pinion  41 , third wheel and pinion (not shown in the figure), center wheel and pinion  42 , minute wheel and pinion  43 , hour wheel and pinion  70 , 24-hour intermediate wheel and pinion  44 , and 24-hour wheel and pinion  45 . 
     Fourth Wheel and Pinion 
     As shown in  FIG. 4 , the fourth wheel and pinion  41  (second hand wheel and pinion) has a center pivot  411  (second hand pivot) to which the second hand  21  is attached, a fourth wheel  412  disposed to the center (fourth) pivot  411 , and a fourth pinion  413 . The fourth wheel  412  engages the fifth wheel, and the fourth pinion  413  engages the third wheel. 
     The back cover end of the center pivot  411  is guided by a hole stone  341  disposed to the wheel train bridge  34 . 
     The crystal-side end of the center pivot  411  is between the crystal and the dial  12 . A protruding part  411 A that protrudes to the outside is disposed to the center pivot  411  at a position between the crystal and the dial  12 . 
     A second arbor  331  (first guide) is disposed to the center wheel bridge  33 . The second arbor  331  is tubular, and is disposed coaxially to the axis O 1  of the center pivot  411 . The crystal-side end of the second arbor  331  is located between the crystal and the dial  12 , and has a guide member  331 A that protrudes to both the inside and the outside. Another guide member  331 B that protrudes to the outside is disposed to the second arbor  331  on the back cover side of the surface of the main plate  32 . 
     The center pivot  411  is inserted to the second arbor  331 , and the protruding part  411 A of the center pivot  411  is guided by the guide member  331 A of the second arbor  331 . As a result, the center pivot  411  is guided (supported) by the second arbor  331 . 
     The fourth wheel  412  and fourth pinion  413  are disposed between the wheel train bridge  34  and the center wheel bridge  33 . 
     Center Wheel and Pinion Configuration 
     The center wheel and pinion  42  (minute hand wheel) includes an arbor  421  (minute hand pivot) to which the minute hand  22  is attached, and a second wheel  422  and second pinion  423  disposed to the arbor  421 . The second wheel  422  engages the third wheel, and the second pinion  423  engages the minute wheel and pinion  43 . 
     The arbor  421  is tubular with a diameter greater than the center pivot  411 , and is disposed coaxially to the axis O 1 . The end of the arbor  421  on the back cover side is disposed between the center wheel bridge  33  and main plate  32  in the axial direction, and the end toward the crystal is between the crystal and the dial  12 . 
     The center pivot  411  and second arbor  331  are inserted inside the arbor  421 , and guide member  331 A and guide member  331 B of the second arbor  331  guide the inside surface of the arbor  421 . The arbor  421  is thus guided by the second arbor  331 . 
     The second wheel  422  and second pinion  423  are disposed between the center wheel bridge  33  and main plate  32 . 
     Hour Wheel and Pinion Configuration 
       FIG. 5  is an oblique view of the hour wheel and pinion  70  (hour hand wheel). Note that the hour wheel body  74  is not shown in  FIG. 5 . 
     As shown in  FIG. 4  and  FIG. 5 , the hour wheel and pinion  70  includes, disposed on the face side of the main plate  32 , the hour wheel  71 , hour jumper  72 , hour jumper pinion  73 , and hour wheel body  74  (first date change intermediate wheel). 
     As shown in  FIG. 4 , the hour wheel body  74  has an arbor  741  that is cylindrical with a greater diameter than arbor  421  and is disposed coaxially to the axis O 1 , and a hour wheel body pinion  742  formed integrally to the arbor  741 . 
     As shown in  FIG. 4  and  FIG. 5 , the hour jumper pinion  73  is cylindrical with a diameter greater than the arbor  421  of the center wheel and pinion  42 , and is disposed coaxially to the axis O 1 . The hour jumper pinion  73  is fit to the hour wheel body  74  from the back cover side, and rotates in unison with the hour wheel body  74 . More specifically, the arbor  741  and hour jumper pinion  73  form the pivot (hour hand pivot) of the hour wheel and pinion  70 . Twelve teeth  731  are disposed circumferentially around the outside surface of the hour jumper pinion  73 . The hour jumper pinion  73  may also referred to as a star wheel. 
     The hour wheel  71  has an annular shape around the outside surface of the hour jumper pinion  73 , and teeth  711  that mesh with the minute wheel and pinion  43  and the 24-hour intermediate wheel and pinion  44  (see  FIG. 3 ) are formed around the outside surface of the hour wheel  71 . An arc member  712 , which forms an arc when seen from the face side, is disposed protruding from the inside circumference edge to the face side of the hour wheel  71 . The arc member  712  encloses at least half of the outside circumference of the hour jumper pinion  73 . 
     The hour jumper  72  is disposed to the face side of the hour wheel  71 . More specifically, as described further below, to increase the torque of the hour jumper  72 , the hour jumper  72  comprises two hour jumper members  721 ,  722  stacked together in the axial direction. The hour jumper members  721 ,  722  in this example are formed in a stamping process. 
     Hour jumper member  721  forms an arc centered on the axis O 1  when seen from the face side, and comprises an hour jumper member body  721 A, and a flexible pawl arm  721 B extending from the circumferential end of the hour jumper member body  721 A. A pawl  721 C that engages the teeth  731  of the hour jumper pinion  73  is disposed to the distal end of the pawl arm  721 B, and the pawl arm  721 B flexes in the direction away from the hour jumper pinion  73 . 
     Hour jumper member  722  has the same shape as hour jumper member  721  in plan view, and the same size and thickness, and like hour jumper member  721  has an hour jumper member body  722 A that is guided by the arc member  712 , and a pawl arm  722 B with a pawl  722 C that engages the teeth  731  of the hour jumper pinion  73 . 
     When seem from the face side, hour jumper member  722  is disposed to the same rotational position as hour jumper member  721 , and is coincident with the hour jumper member  721 . 
     Hour jumper member bodies  721 A,  722 A are fastened to the hour wheel  71  by two fastener pins  723 , and the hour jumper  72  turns in unison with the hour wheel  71 . Note that the fastener pins  723  may be formed in unison with the hour wheel  71 . 
     As shown in  FIG. 4 , a center pipe  321  (second guide) is disposed to the main plate  32 . The center pipe  321  is tubular, and disposed coaxially to the axis O 1 . The center pivot  411  of the fourth wheel and pinion  41 , second arbor  331 , and the arbor  421  of the center wheel and pinion  42  are inserted to the center pipe  321 . The crystal-side end of the center pipe  321  is positioned between the crystal and the back cover side of the date indicator bridge  35  described below. The crystal side end of the center pipe  321  forms a guide  321 A extending toward the outside. Another guide  321 B extending toward the outside is disposed to the back cover side of the center pipe  321  from the guide  321 A. 
     The center pivot  411 , second arbor  331 , arbor  421 , and center pipe  321  are inserted to the arbor  741  of the hour wheel body  74  and the hour jumper pinion  73 , the guide  321 A of the center pipe  321  guides the inside surface of the arbor  741 , and the guide  321 B of the center pipe  321  guides the inside surface of the hour jumper pinion  73 . The hour wheel and pinion  70  is thus guided by the center pipe  321 . 
     When the minute wheel and pinion  43  turns in conjunction with rotation of the rotor, the hour wheel  71  and hour jumper  72  of the hour wheel and pinion  70  configured as described above also turn in conjunction with the minute wheel and pinion  43 . Because the pawls  721 C,  722 C push against the hour jumper pinion  73  at this time, the pawls  721 C,  722 C engage the teeth  731  of the hour jumper pinion  73  and the hour jumper pinion  73  turns in conjunction with the hour jumper  72 . The hour wheel body  74  also turns in unison with the hour jumper pinion  73 . 
     When the hour wheel body  74  is turned by the time difference correction mechanism  60  described below, the hour jumper pinion  73  also turns in unison with the hour wheel body  74 . Because rotation of the hour jumper  72  is limited by the minute wheel and pinion  43  meshed with the hour wheel  71  at this time, the pawl arms  721 B,  722 B are pushed by the teeth  731  of the hour jumper pinion  73  and flex, and the pawls  721 C,  722 C and teeth  731  separate. As a result, the hour wheel body  74  can be turned while the hour jumper  72  remains stationary. 
     As shown in  FIG. 6 , the movement  2  has a date indicator bridge  35  that restricts circumferential movement of the date indicator  25 .  FIG. 6  is a plan view of the movement  2  from the face side. 
     As shown in  FIG. 4 , the date indicator bridge  35  is closer to the face than the hour wheel body pinion  742 . The date indicator bridge  35  includes a round opening  351  coaxial to the axis O 1 , and a tubular portion  352  (third guide) extending toward the face from the outside edge of the opening  351 . The tubular portion  352  is also coaxial to the axis O 1 . The center pivot  411 , second arbor  331 , arbor  421 , and arbor  741  are inserted to the tubular portion  352 . The distal end of the opening  351  is between the crystal and the back cover side of the dial  12 . 
     An annular dial washer  36  (hour hand ring) is disposed between the hour wheel body pinion  742  and the date indicator bridge  35 . The hour wheel and pinion  70  is urged to the main plate  32  by the dial washer  36 . 
     In this embodiment of the invention, the part of the guide  321 A that guides the hour wheel body  74  in the center pipe  321 , and contact between the hour wheel body pinion  742  and the dial washer  36 , are on the same plane perpendicular to the axial direction. As a result, the dial washer  36  urges the hour wheel and pinion  70  while also suppressing tilting of the hour wheel and pinion  70 . 
     Configuration of the 24-Hour Wheel and Pinion 
     As shown in  FIG. 4 , the 24-hour wheel and pinion  45  (24-hour hand wheel) is tubular, and includes an arbor  451  (24-hour hand pivot) disposed coaxially to the axis O 1 , and a 24-hour wheel  452  formed in unison with the arbor  451 . The 24-hour wheel  452  engages the 24-hour intermediate wheel and pinion  44  (see  FIG. 3 ), and turns in conjunction with the hour wheel and pinion  70 . The 24-hour wheel  452  turns one-half revolution for each revolution of the hour wheel and pinion  70 . 
     The arbor  451  has a first tube  451 A formed with a first diameter, and a second tube  451 B disposed on the crystal side of the first tube  451 A and having a second diameter that is smaller than the first diameter. 
     Inside the first tube  451 A are inserted the center pivot  411  of the fourth wheel and pinion  41 , the second arbor  331 , the arbor  421  of the center wheel and pinion  42 , the arbor  741  of the hour wheel body  74 , and the tubular portion  352  of the date indicator bridge  35 ; and part of the tubular portion  352  (guide portion) guides the inside surface of the first tube  451 A. The arbor  451  is thus guided by the tubular portion  352 . Inside the second tube  451 B are inserted the center pivot  411 , the second arbor  331 , arbor  421 , and arbor  741 . 
     The 24-hour wheel  452  is disposed between the date indicator bridge  35  and the dial  12 . 
     An annular dial washer  37  (24-hour hand ring) is disposed between the 24-hour wheel  452  and dial  12 . The 24-hour wheel and pinion  45  is urged to the date indicator bridge  35  by the dial washer  37 . 
     In this embodiment, the part of the tubular portion  352  of the date indicator bridge  35  that guides the 24-hour wheel and pinion  45 , and the point of contact between the 24-hour wheel  452  and the dial washer  37 , are on the same plane perpendicular to the axial direction. As a result, the dial washer  37  urges the 24-hour wheel and pinion  45  while suppressing tilting of the 24-hour wheel and pinion  45 . 
     Configuration of the Date Change Mechanism  50   
       FIG. 7  is a plan view from the face side of the movement  2  without the date indicator bridge  35 , the date indicator guide, the date indicator  25 , and the 24-hour wheel and pinion  45 . 
     As shown in  FIG. 7 , the date change mechanism  50 , also referred to as a calendar change mechanism, includes, disposed on the face side of the calendar plate  31  (see  FIG. 2 ), a setting wheel  51 , second date change intermediate wheel  52 , and date indicator driver  80 . 
     The setting wheel  51  engages the hour wheel body pinion  742  of the hour wheel body  74 , and turns in conjunction with the hour wheel body  74 . The second date change intermediate wheel  52  engages the setting wheel  51 , and turns in conjunction with the setting wheel  51 . The setting wheel  51  and second date change intermediate wheel  52  form an intermediate wheel train. 
     Configuration of the Date Change Mechanism 
       FIG. 8  is an oblique view from the face side of the date indicator driver  80 .  FIG. 9  is an oblique view of the date indicator driver  80  from the back cover side. 
     As shown in  FIG. 2 ,  FIG. 8 , and  FIG. 9 , the date indicator driver  80  includes a support  85  disposed to the calendar plate  31 , an arbor  86  supported by the support  85 , a date change wheel  81  attached rotatably to the arbor  86 , a date change pawl disc  82  supported by and rotating in unison with the arbor  86 , a date change cam  83 , and a date change lever  84  that engages the date change cam  83 . The date change lever  84  is axially supported on a pin  322  disposed to the main plate  32  (see  FIG. 7 ), and positioned in the thickness direction by the calendar plate  31 . 
     The date change wheel  81 , also called a calendar change wheel, engages the second date change intermediate wheel  52 , and rotates in unison with the second date change intermediate wheel  52 . An arc-shaped opening  811  (see  FIG. 10 ) centered on the arbor  86  is formed in the date change wheel  81 . 
     Note that in this embodiment when the setting wheel  51 , second date change intermediate wheel  52 , and date change wheel  81  turn in the forward direction, force works in the direction releasing engagement of the date change wheel  81 , and when these wheels turn in the reverse direction, force works in the direction engaging the date change wheel  81 . 
     The date change pawl disc  82 , or calendar change pawl, is disposed on the face side of the date change wheel  81 , and is substantially disc shaped. The date change pawl disc  82  includes a pawl  821  protruding from the outside surface, and an engagement hole  822 . 
     As shown in  FIG. 6 , the date indicator  25  has 31 teeth  251  on the inside circumference side, and with each revolution of the date change pawl disc  82 , the pawl  821  advances the teeth  251  one tooth. As a result, the date indicator  25  turns the amount of one day, and the number on the date indicator  25  visible through the date window  12 A advances one. 
     The date change cam  83 , or calendar change cam, is disposed to the back cover side of the date change wheel  81 , and is formed in a fan shape centered on the arbor  86 . The date change cam  83  has a stud  831  protruding from face side, and the stud  831  is inserted through the arc-shaped opening  811  in the date change wheel  81 , engaging the engagement hole  822  in the date change pawl disc  82 . 
     The date change lever  84 , or calendar change lever, is flexible and pivotably disposed to the pin  322  of the main plate  32  (see  FIG. 7 ). The distal end  841  of the date change lever  84  (see  FIG. 9 ) contacts the side of the date change cam  83 , and has two protrusions  842 ,  843  on the side that contacts the date change cam  83 . 
     Date Change Operation 
       FIG. 10  and  FIG. 11  are state diagrams illustrating the date change operation. Note that the date change pawl disc  82  is not shown in  FIG. 10 . 
     Before the date is advanced, protrusion  842  of the date change lever  84  is in contact with the arc  832  of the outside surface of the date change cam  83  as shown in state  1  in  FIG. 10  and  FIG. 11 . At this time, the pawl  821  of the date change pawl disc  82  is not touching the teeth  251  of the date indicator  25 . 
     When the date change wheel  81  then turns counterclockwise in conjunction with the second date change intermediate wheel  52 , the stud  831  of the date change cam  83  is pushed by the inside surface of the arc-shaped opening  811  in the date change wheel  81 , and the date change cam  83  turns. As a result, the arc  832  of the date change cam  83  pushes protrusion  842  of the date change lever  84 , causing the date change lever  84  to gradually flex. The date change pawl disc  82  also turns counterclockwise in unison with the date change cam  83 . The date change wheel  81  causes the date change lever  84  to flex for approximately one revolution. 
     As the date change cam  83  continues turning, as shown in state  2  in  FIG. 10  and  FIG. 11 , the arc  832  of the date change cam  83  stops contacting the protrusion  842  of the date change lever  84 , the urging force of the date change lever  84  then causes the protrusion  842  of the date change lever  84  to push the outside radial face  833  of the date change cam  83 , and the date change cam  83  jumps rotationally in the counterclockwise direction. More specifically, the date change cam  83  turns at a faster speed than the date change wheel  81 . Because the stud  831  of the date change cam  83  moves inside the arc-shaped opening  811  of the date change wheel  81  at this time, rotation of the date change cam  83  is not restricted by the date change wheel  81 . The date change pawl disc  82  also turns quickly counterclockwise in unison with the date change cam  83 . 
     When the date change cam  83  turns a specific angle, as shown in state  3  in  FIG. 10  and  FIG. 11 , the pawl  821  contacts the teeth  251  of the date indicator  25 , the date indicator  25  is pushed by the pawl  821  and turns counterclockwise one tooth, and the date visible from the date window  12 A in the dial  12  is advanced one. 
     As the date change cam  83  continues turning, as shown in state  4  in  FIG. 10  and  FIG. 11 , the stud  831  of the date change cam  83  contacts the inside face on the opposite side of the arc-shaped opening  811  in the date change wheel  81 , and rotation of the date change cam  83  stops. Because the date change cam  83  contacts protrusion  843  of the date change lever  84  at this time, rotation of the date change cam  83  is also stopped by the date change lever  84 . 
     By being advanced by the date change pawl disc  82 , the date indicator  25  wants to continue turning counterclockwise due to inertia even after the date indicator  25  loses contact with the pawl  821  of the date change pawl disc  82 , but the date indicator  25  is prevented from turning more than one day by the tooth  251  clockwise adjacent to the tooth  251  of the date indicator  25  that is advanced by the pawl  821  of the date change pawl disc  82 . 
     In this way, the date indicator driver  80  can instantly advance the date indicator  25  one day from state  2  to state  4  in  FIG. 10  and  FIG. 11  due to the restoring force of the date change lever  84  turning the date change cam  83 . More specifically, the number on the date indicator  25  visible from the date window  12 A changes instantly. 
     The date change mechanism  50  may therefore also be called an instant date change mechanism. As a result, the user can reliably see the date on the date indicator  25  in the date window  12 A immediately before and after the date changes at 12:00 p.m. 
     Configuration of the Time Difference Correction Mechanism 
     As shown in  FIG. 3  and  FIG. 7 , the time difference correction mechanism  60  includes a sliding pinion  62  (see  FIG. 3 ) disposed to the winding stem  39 ; a first intermediate setting wheel  63  (see  FIG. 3 ) that turns in conjunction with the sliding pinion  62  when the winding stem  39  is set to the first stop; a second intermediate setting wheel  64  that turns in conjunction with the first intermediate setting wheel  63 ; and a setting wheel  51  that turns in conjunction with the second intermediate setting wheel  64 . 
     The sliding pinion  62 , first intermediate setting wheel  63 , second intermediate setting wheel  64 , and setting wheel  51  thus embody a time difference correction train that turns in conjunction with the winding stem  39 . 
     When the winding stem  39  is pulled out to the first stop and turned axially, the first intermediate setting wheel  63 , second intermediate setting wheel  64 , and setting wheel  51  turn in conjunction with the sliding pinion  62 . As a result, the hour wheel body  74  turns and the hour indicated by the hour hand  23  changes. 
     The hour jumper pinion  73  turns in unison with the hour wheel body  74  at this time, but as described above, because rotation of the hour jumper  72  is restricted by the minute wheel and pinion  43  engaged with the hour wheel  71 , the pawl arms  721 B,  722 B flex, and engagement of the teeth  731  of the hour jumper pinion  73  with the pawls  721 C,  722 C is released. The hour wheel body  74  therefore turns while the hour jumper  72  and hour wheel  71  remain stationary. As a result, of the second hand  21 , minute hand  22 , hour hand  23 , and 24-hour hand  24 , the hour indicated by the hour hand  23  can be changed. 
     Note that because the teeth  731  of the hour jumper pinion  73  are disposed at 12 equal intervals, the hour wheel body  74  can be turned a 1-hour distance each time the winding stem  39  is turned and the teeth  731  and pawls  721 C,  722 C are disengaged. More specifically, the time indicated by the hour hand  23  can be changed in 1-hour increments. 
     Torque of the Hour Jumper 
     Because the date change lever  84  of the date change mechanism  50  must be advanced by rotation of the hour wheel body  74 , greater torque is required to turn the hour wheel body  74  than in a conventional date change mechanism that does not have a date change lever  84 . 
       FIG. 12  is a graph showing the torque required to turn the hour wheel body  74  (load torque) in relation to the time. Dot-dot-dash line P 1  shows the maximum load torque (forward rotation) of the date change mechanism  50 , and solid line P 2  shows the average load torque (forward rotation) of the date change mechanism  50 . Dot-dash line P 3  shows the maximum load torque (reverse rotation) of the date change mechanism  50 , and solid line P 4  shows the average load torque (reverse rotation) of the date change mechanism  50 . 
     Dotted line P 5  shows the maximum load torque (forward rotation) of the date jumper  87  (see  FIG. 6 ,  FIG. 7 ), and solid line P 6  shows the average load torque (forward rotation) of the date jumper  87 . Solid line P 7  shows the maximum load torque (reverse rotation) of the date jumper  87 , and dotted line P 8  shows the average load torque (reverse rotation) of the date jumper  87 . 
     Dot-dash line P 9  shows the total load torque. Note that  FIG. 12  is a graph for when the hour jumper  72  comprises a single hour jumper member. Torque is doubled when the hour jumper  72  comprises two hour jumper members. 
     As will be understood from  FIG. 12 , the date change mechanism  50  is configured so that forward rotation requires less torque than reverse rotation. 
     The dotted line P 10  in  FIG. 12  shows the minimum torque of the hour jumper  72 , and the dot-dash line P 11  shows the average torque of the hour jumper  72 . The torque of the hour jumper  72  is used to turn the hour wheel body  74 , and must therefore be greater than the load torque of the hour wheel body  74 . More specifically, the spring force (urging force) of the hour jumper  72  must be greater than the load torque of the hour wheel body  74 . As a result, in this embodiment as described above, the hour jumper  72  comprises two hour jumper members  721 ,  722  to increase the torque, and the minimum torque of the hour jumper  72  indicated by the dotted line P 10  is greater than the load torque of the hour wheel body  74  indicated by the lines P 1  to P 9 . 
     Note that in this embodiment the thickness of the hour jumper  72  (the dimension in the direction aligned with the hand pivots) is set to 1.5 times (or 2 times) or greater than the thickness of the fourth wheel  412 , second wheel  422 , the hour wheel  71 , the hour wheel body pinion  742 , and the date change wheel  81 . 
     Operating Effect 
     In a timepiece  1  according to this embodiment, because the second arbor  331  is disposed between the center pivot  411  of the fourth wheel and pinion  41  and the arbor  421  of the center wheel and pinion  42 , contact between the center pivot  411  and the arbor  421  can be suppressed, and rotation of the arbor  421  in conjunction with rotation of the center pivot  411  can be suppressed. In addition, rotation of the arbor  421  in conjunction with rotation of the center pivot  411  due to the lubricant injected between the center pivot  411  and arbor  421  can be suppressed. 
     Furthermore, because the center pipe  321  is disposed in this timepiece  1  between the arbor  421  and the arbor  741  of the hour wheel body  74  and the hour jumper pinion  73 , contact between the arbor  421  and the arbor  741  and hour jumper pinion  73  can be suppressed, and rotation of the arbor  741  and hour jumper pinion  73  in conjunction with rotation of the arbor  421  can be suppressed. In addition, rotation of the arbor  741  and hour jumper pinion  73  in conjunction with rotation of the arbor  421  due to the lubricant injected between the arbor  421  and the arbor  741  and hour jumper pinion  73  can be suppressed. 
     In addition, rotation of the arbor  421  of the center wheel and pinion  42 , and the arbor  451  of the 24-hour wheel and pinion  45 , in conjunction with rotation of the arbor  741  of the hour wheel body  74  when correcting the time difference can be suppressed. 
     Furthermore, because the tubular portion  352  of the date indicator bridge  35  is disposed between the arbor  741  and the arbor  451  of the 24-hour wheel and pinion  45  in this timepiece  1 , contact between the arbor  741  and arbor  451  can be suppressed, and rotation of the arbor  451  in conjunction with rotation of the arbor  741  can be suppressed. Rotation of the arbor  451  in conjunction with rotation of the arbor  741  due to the lubricant injected between the arbors can be suppressed. 
     Rotation of one arbor due in conjunction with rotation of another arbor can thus be suppressed in a timepiece  1  according to this embodiment of the invention. 
     In this timepiece  1 , the guide disposed between the arbor  741  of the hour wheel body  74  and the arbor  451  of the 24-hour wheel and pinion  45  is embodied by a tubular portion  352 , which is part of the date indicator bridge  35 , there is no need to provide a another part to configure the guide, and the parts count can be reduced. 
     Furthermore, because this guide is configured by a part of the date indicator bridge  35 , the date indicator bridge  35  can be disposed to a position near the hour wheel body  74 , and a dial washer  36  can be disposed between the hour wheel body  74  and date indicator bridge  35 . This configuration enables suppressing, by means of the dial washer  36 , movement of the hour wheel and pinion  70  in the axial direction. 
     In addition, because the part of the guide  321 A that guides the hour wheel body  74  in the center pipe  321 , and contact between the hour wheel body pinion  742  and dial washer  36 , are on the same plane perpendicular to the axial direction, the hour wheel and pinion  70  can be prevented from tilting while the dial washer  36  suppresses movement of the hour wheel and pinion  70  in the axial direction. 
     Because the second arbor  331  is disposed to the center wheel bridge  33  in this timepiece  1 , another part is not needed to hold the second arbor  331 . In addition, because the center pipe  321  is disposed to the main plate  32 , there is no need to provide a separate part to hold the center pipe  321 . As a result, the parts count can be reduced. 
     In this timepiece  1 , the center pivot  411  of the fourth wheel and pinion  41  is guided by the wheel train bridge  34  and the second arbor  331  disposed to the center wheel bridge  33 . As a result, the center pivot  411  can be guided without the fourth wheel and pinion  41  tilting. 
     Because a dial washer  37  is disposed between the 24-hour wheel  452  and dial  12  in this timepiece  1 , movement of the 24-hour wheel and pinion  45  in the axial direction can be suppressed by the dial washer  37 . Furthermore, because the part of the tubular portion  352  of the date indicator bridge  35  that guides the 24-hour wheel and pinion  45 , and the point of contact between the 24-hour wheel  452  and the dial washer  37 , are on the same plane perpendicular to the axial direction, the 24-hour wheel and pinion  45  can be prevented from tilting while the dial washer  37  suppresses movement of the 24-hour wheel and pinion  45  in the axial direction. 
     In the timepiece  1  described above, the hour jumper  72  is configured from multiple hour jumper members  721 ,  722 . As a result, the torque, that is, the spring force, of the hour jumper  72  can be made greater than when the hour jumper  72  is made from a single hour jumper member. 
     Even if the hour jumper  72  is made from a single hour jumper member, the spring force can be increased by increasing the thickness of the single hour jumper member. However, if the ratio of the thickness to the width of the pawl arm of the hour jumper member increases, forming the hour jumper member by stamping becomes difficult, and easily manufacturing the hour jumper member may not be possible. However, because there is no need to increase the thickness of the individual hour jumper members  721 ,  722  in the timepiece  1  according to this embodiment, the hour jumper members  721 ,  722  can be easily made by stamping, and the hour jumper  72  can be easily manufactured. 
     In another example, spring force can be increased by changing the plane shape of the single hour jumper member. In this case, however, the force per unit area of the hour jumper pinion  73  increases, wear resistance decreases, and the hour jumper member must be redesigned. In contrast, because the timepiece  1  according to this embodiment maintains wear resistance without changing the force per unit area on the hour jumper pinion  73 , and does not require changing the shape of the hour jumper members  721 ,  722 , less time is required to design the hour jumper  72 . 
     Because the timepiece  1  according to this embodiment enables easily increasing the torque of the hour jumper  72 , the types of mechanisms that can be driven by the hour wheel body  74  can be increased, and different types of timepieces can be easily manufactured. 
     The hour jumper members  721 ,  722  of this timepiece  1  have the same plane shape, size, and thickness. As a result, there is no need to manufacture multiple types of hour jumper members, and the manufacturing process and parts management can be simplified. 
     The stop position of the hour wheel body  74  when correcting the time difference is determined by the teeth  731  of the hour jumper pinion  73 . Therefore, by fixing the hour jumper pinion  73  to the hour wheel body  74 , and the hour wheel body  74  turning in unison with the hour jumper pinion  73 , the stop position of the hour wheel body  74  can be prevented from shifting more reliably than when the hour wheel body  74  is affixed to the hour jumper  72 , and the hour jumper pinion  73  is affixed to the hour wheel  71 . As a result, shifting of the position indicated by the hour hand  23  when adjusting the time difference can be reduced. 
     In the timepiece  1  according to this embodiment, the hour jumper member bodies  721 A,  722 A of the hour jumper members  721 ,  722  are guided by the arc member  712  disposed to the hour wheel  71 . As a result, the hour jumper members  721 ,  722  can be reliably positioned by the arc member  712 , and the position of the hour jumper members  721 ,  722  shifting and the torque of the hour jumper  72  changing can be suppressed. 
     When the winding stem  39  is operated and the time difference correction train turned in this timepiece  1 , the hour jumper  72  and hour jumper pinion  73  disengage, and the hour wheel body  74  turns while the hour wheel  71  remains stationary. As a result, the hour indicated by the hour hand  23  can be corrected without changing the hour indicated by the 24-hour hand  24  attached to the 24-hour wheel and pinion  45 , which moves in conjunction with the hour wheel  71 . 
     In this timepiece  1 , the date change wheel  81  turns in conjunction with the hour wheel body  74 , the date change cam  83  turns in conjunction with the date change wheel  81 , and the date change lever  84  gradually bends. When the date change cam  83  turns to a specific rotational position, the spring force of the flexed date change lever  84  causes the date change cam  83  to rotate instantly, and the date change pawl disc  82  that turns in unison with the date change cam  83  advances the date indicator  25 . As a result, the date can be advanced instantly in a timepiece  1  having this time difference correction function. 
     Furthermore, because the date change wheel  81  turns in conjunction with the hour wheel body  74  in this timepiece  1 , by operating the winding stem  39  to turn the time difference correction train and turn the hour wheel body  74 , the date can be adjusted simultaneously to the hour indicated by the hour hand  23 , and convenience can be improved compared with a configuration in which adjusting the hour and adjusting the date are done by separate operations. 
     The thickness of the hour jumper  72  in this timepiece  1  is greater (1.5 times to 2 times greater in this embodiment) than the thickness of the hour wheel  71 , for example. This configuration suppresses bending of the hour jumper  72  in the direction perpendicular (the direction aligned with the axial direction of the hour wheel and pinion  70 ) to the flexing direction of the hour jumper  72  better than in a configuration in which the thickness of the hour jumper  72  is the same as the thickness of the hour wheel  71 . More specifically, twisting of the hour jumper  72  can be suppressed. As a result, spring force in the flexing direction of the hour jumper  72  can be stabilized, and the torque of the hour jumper  72  can be stabilized. 
     By making the thickness of the hour jumper  72  greater than the thickness of the hour wheel  71 , the size of the part where the hour jumper  72  and hour jumper pinion  73  engage (the dimension in the axial direction of the hour jumper pinion  73 ) can be made greater than half the combined thickness of the hour wheel  71  and hour jumper  72 . As a result, tilting of the hour jumper  72  and hour wheel  71  when adjusting the time difference can be suppressed better than when the hour jumper  72  and hour wheel  71  are the same thickness. 
     In this timepiece  1 , the date change wheel  81  turns in conjunction with the hour wheel body  74  through the intermediate wheel train (the setting wheel  51  and second date change intermediate wheel  52 ). Compared with a configuration in which the hour wheel body  74  meshes directly with the date change wheel  81 , this configuration increases the number of meshing teeth, and can therefore more easily absorb the force of impact when a sudden shock is applied to the movement  2 , for example. As a result, the positions of the hour wheel body  74  and date change wheel  81  shifting when such a force is applied can be suppressed. In addition, the direction of rotation of the date change wheel  81  relative to the direction of rotation of the hour wheel body  74 , and the position of the date change wheel  81  relative to the hour wheel body  74 , can be adjusted. 
     In this timepiece  1 , the setting wheel  51  is used in the time difference correction train and is also used in the intermediate wheel train of the date change mechanism  50 . More specifically, one wheel in the time difference correction train, and one wheel in the intermediate wheel train, are the same wheel. As a result, compared with a configuration in which all wheels of the intermediate wheel train, and all wheels of the time difference correction train, are separate wheels, the number of wheels can be reduced and the parts count can be reduced. 
     Note that the number of common wheels may also be two or more. 
     In this timepiece  1 , the hour wheel and pinion  70  is disposed on the face side of the main plate  32 , and the setting wheel  51 , second date change intermediate wheel  52 , and date indicator driver  80  are disposed on the face side of the calendar plate  31 . In other words, the position of the hour wheel and pinion  70  in the axial direction is determined by the main plate  32 , and the positions of the setting wheel  51 , second date change intermediate wheel  52 , and date indicator driver  80  are determined by the calendar plate  31 . 
     Compared with a configuration in which the setting wheel  51 , second date change intermediate wheel  52 , and date indicator driver  80  are disposed to the face side of the main plate  32  like the hour wheel and pinion  70 , the configuration of this embodiment simplifies positioning the setting wheel  51 , second date change intermediate wheel  52 , and date indicator driver  80  in the axial direction, and suppresses variation in the position in the axial direction. 
     Furthermore, because the setting wheel  51 , second date change intermediate wheel  52 , and date change wheel  81  can be positioned on substantially the same plane, tilting of the wheels can be suppressed when force is applied to the wheels while adjusting the time difference. As a result, by increasing the torque of the hour jumper  72 , the force required to turn the hour wheel body  74  when adjusting the time difference is increased, and the time difference can be appropriately adjusted even if the force applied to the wheels increases. 
     Other Embodiments 
     The invention is not limited to the embodiments described above, and can be modified and improved in many ways without departing from the scope of the accompanying claims. 
     Variation 1 
     In the embodiment described above the date change mechanism  50  turns the date indicator  25 , but the invention is not so limited. For example, when the timepiece  1  has a day wheel, the day wheel may be turned by the date change mechanism.  FIG. 13  and  FIG. 14  are state diagrams illustrating the date change operation in this variation. Note that the date change pawl disc  82  is not shown in  FIG. 13 . 
     As shown in state  1  in  FIG. 14 , the date change pawl disc  82 A of the date change mechanism  50 A in this variation has, in addition to pawl  821 , two pawls  823 ,  824  for advancing the teeth  261  of a day wheel  26  disposed to a day indicator. The day wheel  26  has 14 teeth  261 . As a result, the day is advanced one day when the day wheel  26  is advanced two teeth. 
     As described in the foregoing embodiment, before the day is advanced, the date change cam  83  turns counterclockwise in conjunction with the date change wheel  81 , and the arc  832  of the date change cam  83  pushes the protrusion  842  of the date change lever  84 , gradually causing the date change lever  84  to flex. 
     As the date change cam  83  continues turning, as shown in state  1  in  FIG. 13 , the arc  832  of the date change cam  83  stops contacting the protrusion  842  of the date change lever  84 , the restoring force of the date change lever  84  then causes the protrusion  842  of the date change lever  84  to push the outside radial face  833  of the date change cam  83 , and the date change cam  83  jumps rotationally in the counterclockwise direction. 
     Because the stud  831  of the date change cam  83  moves inside the arc-shaped opening  811  of the date change wheel  81  at this time, rotation of the date change cam  83  is not restricted by the date change wheel  81 . The date change pawl disc  82  also turns quickly counterclockwise in unison with the date change cam  83 . 
     When the date change cam  83  turns a specific angle, as shown in state  2  in  FIG. 13  and  FIG. 14 , pawl  823  contacts a tooth  261  of the day wheel  26 , the day wheel  26  is pushed by the pawl  823  and turns counterclockwise one tooth. 
     As the date change pawl disc  82 A turns further, as shown in state  3  in  FIG. 13  and  FIG. 14 , pawl  821  contacts the teeth  251  of the date indicator  25 , the date indicator  25  is pushed by the pawl  821  and turns counterclockwise one tooth (one day). 
     As the date change pawl disc  82 A turns further, as shown in state  4  in  FIG. 13  and  FIG. 14 , pawl  824  contacts a tooth  261  of the day wheel  26 , the day wheel  26  is pushed by the pawl  824  and turns counterclockwise one tooth. As a result, the day changes one day. 
     As the date change pawl disc  82 A continues turning, as shown in state  5  in  FIG. 13  and  FIG. 14 , the stud  831  of the date change cam  83  contacts the inside face on the opposite side of the arc-shaped opening  811  in the date change wheel  81 , and rotation of the date change cam  83  stops. Because the date change cam  83  contacts protrusion  843  of the date change lever  84  at this time, rotation of the date change cam  83  is also stopped by the date change lever  84 . 
     In this way, as shown by state  2  to state  4  in  FIG. 13  and  FIG. 14 , the date change mechanism  50 A can instantly advance the date indicator  25  and the day wheel  26  one day by turning the date change cam  83  by the spring force of the date change lever  84 . 
     Note that the date change mechanism in this first variation describes changing both the date indicator  25  and a day wheel, but the date change mechanism may be configured to turn only a day wheel. 
     Variation 2 
     In the embodiment described above, the guide disposed between the arbor  741  of the hour wheel body  74  and the arbor  451  of the 24-hour wheel and pinion  45  is embodied by tubular portion  352 , which is part of the date indicator bridge  35 , but the invention is not so limited. 
     For example, the guide may be embodied by part of a date indicator guide bridge that guides the date indicator  25 , or by the center pipe or other separately provided part. 
     Variation 3 
     In the embodiment described above, the second arbor  331  is disposed to the center wheel bridge  33 , and the center pipe  321  is disposed to the main plate  32 , but the invention is not so limited. 
     For example, the second arbor  331  and center pipe  321  may be disposed to a support bridge of the movement  2 . 
     Variation 4 
     In the embodiment described above the hour jumper  72  is made from two hour jumper members  721 ,  722 , but the invention is not so limited. 
     More specifically, the hour jumper  72  may be made from three or more hour jumper members according to the torque required to turn the hour wheel body  74 . In this case, by making the hour jumper members of the hour jumper  72  to the same plane shape, size, and thickness, the torque of the hour jumper  72  can be increased to 2, 3, 4, or more times the torque of a single hour jumper member by simply increasing the number of hour jumper members, and the torque of the hour jumper  72  can be easily adjusted. 
     The hour jumper  72  may also be made from a single hour jumper member with greater thickness. If the ratio of the width to the thickness of the pawl arm of the hour jumper member is in the range 0.2 to 0.5, the hour jumper member can be manufactured by a laser or wire cutting process, for example. 
     The number of hour jumper members in the hour jumper  72  may also differ according to one or more of the plane shape, size, and thickness of each hour jumper member. 
     For example, by changing at least one of the plane shape, size, and thickness of the pawl arm of each hour jumper member, the torque of the individual hour jumper member can be changed. As a result, the torque of the hour jumper  72  can be adjusted with greater precision than when the plane shape, size, and thickness of the pawl arms are the same. 
     Furthermore, by changing at least one of the plane shape, size, and thickness of the hour jumper member body of each hour jumper member, the configuration (fastening structure) for attaching the hour jumper member to the hour wheel  71  can be set individually for each hour jumper member. 
     Variation 5 
     In the embodiment described above, the hour jumper members  721 ,  722  of the hour jumper  72  are fastened at the same position when seen from the face side, but the invention is not so limited. 
     More specifically, the hour jumper members  721 ,  722  may be secured at different pivot points. In other words, the pawls  721 C,  722 C may be configured to engage mutually different teeth  731  of the hour jumper pinion  73 . For example, hour jumper members  721 ,  722  may be fastened at pivot points 180 degrees apart. In this case, the center of gravity of the hour jumper  72  can be superimposed with the center of gravity of the hour wheel  71 , and tilting of the hour wheel  71  can be suppressed. 
     The part of the hour jumper pinion  73  that is pushed by the pawls  721 C,  722 C may also be separated circumferentially. In addition, because the spring force of pawl  721 C and the spring force of pawl  722 C work in directions cancelling each other, tilting of the hour wheel  71  can be suppressed. 
     Variation 6 
     In the embodiment described above, the hour wheel body  74  and the hour jumper pinion  73  are attached, and the hour wheel  71  and hour jumper  72  are attached, but the invention is not so limited. 
     For example, in another configuration the hour wheel body  74  and the hour jumper  72  may be attached, and the hour wheel  71  and the hour jumper pinion  73  may be attached. 
     In this case, however, the size of the hour wheel body  74  must be matched to the size of the hour jumper  72 , and the size of the hour wheel body  74  increases accordingly. In addition, the size of the date change wheel  81 , which turns at half the speed of the hour wheel body  74 , must be increased, and the size of the movement  2  increases according. 
     Furthermore, the hour wheel body  74  is preferably nonmetallic because the hour hand  23  is attached. In this case, welding cannot be used to fasten the hour wheel body  74  and hour jumper  72 . 
     Furthermore, because the hour wheel body  74  is not fastened to the hour jumper pinion  73  that determines the stop position of the hour wheel body  74  in the time difference correction operation, the stop position of the hour wheel body  74  can shift when adjusting the time difference. 
     For the foregoing reasons, the hour wheel body  74  is attached to the hour jumper pinion  73 , and the hour wheel  71  is attached to the hour jumper  72 , in the embodiment described above. 
     Variation 7 
     In the embodiment described above, the second date change intermediate wheel  52  turns in conjunction with the hour wheel body pinion  742  of the hour wheel body  74  through the setting wheel  51 , which is part of the time difference correction train, but the invention is not so limited. For example, a configuration in which the second date change intermediate wheel  52  turns in conjunction with the hour wheel body pinion  742  through a separate wheel is conceivable. 
     Variation 8 
     In the embodiment described above, the date change wheel  81  turns in conjunction with the hour wheel body pinion  742  through an intermediate wheel train (setting wheel  51  and second date change intermediate wheel  52 ), but the invention is not so limited. For example, the date change wheel  81  may mesh directly with the hour wheel body pinion  742 . In this configuration, the torque required to turn the date change wheel  81  can be reduced. 
     Variation 9 
     The embodiment described above describes an example applying the invention to an electronic timepiece, but the invention can obviously also be applied to a mechanical timepiece. 
     The invention being thus described, it will be obvious that it may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
     The entire disclosure of Japanese Patent Application No. 2017-184151, filed Sep. 25, 2017 is expressly incorporated by reference herein.