Patent Publication Number: US-8971157-B2

Title: Display apparatus and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2012-030616, filed Feb. 15, 2012, the entire contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display apparatus used in a device, such as a timepiece and calendar apparatus or an instrument meter, and an electronic device equipped with the display apparatus. 
     2. Description of the Related Art 
     For example, as described in Japanese Patent Application Laid-Open (Kokai) Publication No. 54-024674 (corresponding to U.S. Pat. No. 4,276,628), an electronic watch is known. In this watch, when a motor serving as a driving section rotates in the forward direction, a date wheel and a month wheel are not rotated even when a time gear train rotates in the forward direction and moves the hands. When the motor rotates in the reverse direction, the date wheel and the month wheel are rotated via the time gear train, whereby date and month displays are changed and updated. 
     In this type of display apparatus of an electronic watch, dates, from the 1st to the 31st, are displayed on the date wheel. Therefore, when the 31st day is displayed at the end of the “small month” (consisting of 30 days, i.e., smaller by one day than 31 days) the 31st day needs to be detected by a calendar detector mechanism, whereby a control circuit controls so that the date is changed once more by feeding the date wheel. Thus, the display apparatus of the electronic watch includes a restricting lever that restricts the rotation of the month wheel, a conductive pin that is provided in a position where the date wheel displays the 31st, and a switch spring that has an insulated portion and comes in and out of contact with the conductive pin. As a result of this configuration, the 31st day which should not be included in the small month is detected. 
     In this type of display apparatus of an electronic watch, when the month wheel displays “large month” (consisting of 31 days), the restricting lever outwardly pushes up the insulated portion of the switch spring, whereby the switch spring does not come in contact with the conductive pin. When the month wheel displays a “small month”, the restricting lever does not push the insulated portion of the switch spring, whereby the switch spring comes in contact with the conductive pin. As a result, the 31st day which should not be included in the small month is detected. 
     However, to detect the 31st day which should not be included in the small month, this type of display apparatus for an electronic watch requires various components, such as the restricting lever that restricts the rotation of the month wheel, the conductive pin that is provided in the position where the date wheel displays the 31st, and the switch spring that has the insulated portion and comes in and out of contact with the conductive pin. As a result, the large number of components makes the display apparatus complicated to assemble and easily leads to malfunctions. 
     An object of the present invention is to provide a display apparatus having a simple structure that can easily and appropriately change a plurality of displays by forward rotation and reverse rotation of a driving section, and an electronic device including the display apparatus. 
     SUMMARY OF THE INVENTION 
     In order to achieve the above-described object, in accordance with one aspect of the invention, there is provided a display apparatus includes: a first display wheel which has a first display section; a second display wheel which has a second display section; a driving section which rotates in a forward direction and a reverse direction, and rotates the first display wheel in the forward direction and the reverse direction; and a rotating section which rotates only the first display wheel in the forward direction when the first display wheel is rotated in the forward direction, and rotates the second display wheel in the reverse direction together with the first display wheel when the first display wheel is rotated in the reverse direction. 
     The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an enlarged front view of a first embodiment in which the present invention is applied to an electronic wristwatch; 
         FIG. 2  is an enlarged front view of main sections of a calendar mechanism section in a timepiece module of the electronic wristwatch shown in  FIG. 1 . 
         FIG. 3  is an enlarged cross-sectional view of the main sections of the calendar mechanism section shown in  FIG. 2 , taken along line A-A; 
         FIG. 4A  and  FIG. 4B  are diagrams of a first display wheel of the calendar mechanism section shown in  FIG. 2 , in which  FIG. 4A  is an enlarged front view thereof and  FIG. 4B  is an enlarged cross-sectional view thereof taken along line B-B; 
         FIG. 5A ,  FIG. 5B , and  FIG. 5C  are diagrams of a second display wheel of the calendar mechanism section shown in  FIG. 2 , in which  FIG. 5A  is an enlarged front view thereof,  FIG. 5B  is an enlarged cross-sectional view thereof taken along line C-C, and  FIG. 5C  is an enlarged cross-sectional view of main sections thereof taken along line D-D; 
         FIG. 6A  and  FIG. 6B  are diagrams of a brake member of the calendar mechanism section shown in  FIG. 3 , in which  FIG. 6A  is an enlarged front view thereof and  FIG. 6B  is an enlarged cross-sectional view of main sections thereof taken along line E-E; 
         FIG. 7  is an enlarged front view of a portion where first clutch teeth of the first display wheel and second clutch teeth of the second display wheel are meshed in the calendar mechanism section shown in  FIG. 2 ; 
         FIG. 8  is an enlarged cross-sectional view of main sections of the portion where the first clutch teeth of the first display wheel and the second clutch teeth of the second display wheel are meshed shown in  FIG. 7 , taken along line F-F; 
         FIG. 9A ,  FIG. 9B , and  FIG. 9C  are diagrams of a correspondence relationship between a sloped recessing section of the second display wheel and a flat spring section of the brake member shown in  FIG. 3 , in which  FIG. 9A  is an enlarged cross-sectional view of main sections in a state where the flat spring section of the brake member is engaged with the sloped recessing section of the second display wheel,  FIG. 9B  is an enlarged cross-sectional view of main sections in a state where, when the second display wheel idles, the flat spring section of the brake member is engaged with the sloped recessing section of the second display wheel and then pressed downward, thereby being resiliently deformed, and  FIG. 9C  is an enlarged cross-sectional view of main sections in a state where, when the second display wheel rotates in response to the reverse rotation of the first display wheel, the flat spring section of the brake member is disengaged from the sloped recessing section of the second display wheel; 
         FIG. 10A ,  FIG. 10B  and  FIG. 10C , are diagrams of the calendar mechanism section shown in  FIG. 2  showing operating states of a portion where the first clutch teeth of the first display wheel and the second clutch teeth of the second display wheel become unmeshed when the first display wheel rotates in the forward direction, in which  FIG. 10A  is an enlarged front view of main sections when the first display wheel rotates in the forward direction,  FIG. 10B  is an enlarged cross-sectional view of main sections in a state where the first clutch teeth and the second clutch teeth slide against each other and whereby the second display wheel idles, and  FIG. 10C  is an enlarged cross-sectional view of main sections in a state where the flat spring section of the brake member is engaged with the sloped recessing section of the second display wheel and then pressed downward, thereby being resiliently deformed; 
         FIG. 11A ,  FIG. 11B , and  FIG. 11C  are diagrams of the calendar mechanism section shown in  FIG. 2  showing operating states of a portion where the first clutch teeth of the first display wheel and the second clutch teeth of the second display wheel are meshed when the first display wheel rotates in the reverse direction, in which  FIG. 11A  is an enlarged front view of main sections when the first display wheel  5  rotates in the reverse direction,  FIG. 11B  is an enlarged cross-sectional view of main sections in a state where the first clutch teeth and the second clutch teeth are meshed and the second display wheel is rotated together with the first display wheel, and  FIG. 11C  is an enlarged cross-sectional view of main sections in a state where the fiat spring section of the brake member is disengaged from the sloped recessing section of the second display wheel in response to the rotation of the second display wheel; 
         FIG. 12  is a block diagram of a circuit configuration of the timepiece module in the electronic wristwatch shown in  FIG. 1 ; 
         FIG. 13  is an operation flow of control processing for driving a timepiece and driving a calendar performed by a CPU of a control section in the circuit configuration shown in  FIG. 12 ; 
         FIG. 14  is a diagram of an operation flow of date change processing of the calendar mechanism section performed in the control processing shown in  FIG. 13 ; 
         FIG. 15A ,  FIG. 15B , and  FIG. 15C  are diagrams of date changing states at the end of the month in the date change processing shown in  FIG. 14 , in which  FIG. 15A  is a diagram of a date display state at 23:59:50 at the end of the month,  FIG. 15B  is a diagram of a state where the first display wheel rotates in the reverse direction from the display state shown in  FIG. 15A  and whereby display of a second digit is changed from the date display state shown in  FIG. 15A  to the display state shown as a second digit of the following day, and  FIG. 15C  is a diagram of a state where the first display wheel rotates in the forward direction from the display state shown in  FIG. 15B  and whereby display of a first digit is changed from the date display state shown in  FIG. 15B  to the display state shown as a first digit of the following day and whereby the date is updated; 
         FIG. 16  is an enlarged front view of main sections of a calendar mechanism section of a second embodiment where the present invention is applied to an electronic wristwatch; 
         FIG. 17  is an enlarged cross-sectional view of main sections of the calendar mechanism section shown in  FIG. 16 , taken along line G-G; 
         FIG. 18A ,  FIG. 18B , and  FIG. 18C  are diagrams of a portion where first clutch teeth of a first display wheel and second clutch teeth of a second display wheel are meshed in the calendar mechanism section shown in  FIG. 16 , in which  FIG. 18A  is an enlarged front view of main sections thereof  18 B is an enlarged cross-sectional view of main sections taken along line H-H, and  FIG. 18C  is an enlarged cross-sectional view of main sections showing an engaging state where a sloped recessing section of the second display wheel and a flat spring section of a brake member engage; 
         FIG. 19A ,  FIG. 19B , and  FIG. 19C  are diagrams of the calendar mechanism section shown in  FIG. 18A ,  FIG. 18B , and  FIG. 18C , showing operating states of a portion where the first clutch teeth of the first display wheel and the second clutch teeth of the second display wheel become unmeshed when the first display wheel rotates in the forward direction, in which  FIG. 19A  is an enlarged front view of main sections when the first display wheel rotates in the forward direction,  FIG. 19B  is an enlarged cross-sectional view of main sections in a state where the first clutch teeth and the second clutch teeth slide against each other and whereby the second display wheel idles, and  FIG. 19C  is an enlarged cross-sectional view of main sections in a state where the flat spring section of the brake member is engaged with the sloped recessing section of the second display wheel and then pressed downward, thereby being resiliently deformed; 
         FIG. 20A ,  FIG. 20B , and  FIG. 20C  are diagrams of the calendar mechanism section shown in  FIG. 18A ,  FIG. 18B , and  FIG. 18C , showing operating states of a portion where the first clutch teeth of the first display wheel and the second clutch teeth of the second display wheel are meshed when the first display wheel rotates in the reverse direction, in which  FIG. 20A  is an enlarged front view of main sections when the first display wheel  5  rotates in the reverse direction,  FIG. 20B  is an enlarged cross-sectional view of main sections in a state where the first clutch teeth and the second clutch teeth are meshed and the second display wheel rotates together with the first display wheel, and  FIG. 20C  is an enlarged cross-sectional view of main sections in a state where the flat spring section of the brake member is disengaged from the sloped recessing section of the second display wheel in response to the rotation of the second display wheel; 
         FIG. 21  is an enlarged front view of main sections of a calendar mechanism section of a third embodiment where the present invention is applied to an electronic wristwatch; 
         FIG. 22  is an enlarged cross-sectional view of main sections of the calendar mechanism section shown in  FIG. 21 , taken along line I-I; 
         FIG. 23  is an enlarged front view of a brake member of the calendar mechanism section shown in  FIG. 21 ; 
         FIG. 24A  and  FIG. 24B  are diagrams of braking states where the brake member of the calendar mechanism section shown in  FIG. 21  applies a brake on the rotation of a second display wheel, in which  FIG. 24A  is an enlarged front view of main sections in a state where second saw teeth of the second display wheel are meshed with first saw teeth of the brake member, and the position of the second display wheel is restricted, and whereby the second display wheel idles when a first display wheel rotates in the forward direction, and  FIG. 24B  is an enlarged front view of the main sections in a state where the meshing between the second saw teeth of the second display wheel and the first saw teeth of the brake member becomes unmeshed, and whereby the second display wheel is rotated together with the first display wheel when the first display wheel rotates in the reverse direction; 
         FIG. 25  is an enlarged front view of main sections of a variation example of the calendar mechanism section using the brake member of the third embodiment of the present invention; 
         FIG. 26  is an enlarged front view of main sections of a variation example of the calendar display of the calendar mechanism section according to the first embodiment and the third embodiment of the present invention; 
         FIG. 27  is an enlarged front view of main sections of another variation example of the calendar display of the calendar mechanism section according to the second embodiment of the present invention; 
         FIG. 28  is an enlarged front view of main sections of a calendar mechanism section of a fourth embodiment where the present invention is applied to an electronic wristwatch; 
         FIG. 29  is an enlarged cross-sectional view of main sections of the calendar mechanism section shown in  FIG. 28 , taken along time J-J; 
         FIG. 30  is an enlarged front view of a first display wheel of the calendar mechanism section shown in  FIG. 28 ; 
         FIG. 31  is an enlarged front view of a second display wheel of the calendar mechanism section shown in  FIG. 28 ; 
         FIG. 32  is an enlarged front view of a variation example of the second display wheel according to the fourth embodiment of the present invention; 
         FIG. 33  is an enlarged front view of main sections in a variation example of the calendar mechanism section according to the fourth embodiment of the present invention; 
         FIG. 34  is an enlarged planar view of a first display section of the calendar mechanism section shown in  FIG. 33 ; and 
         FIG. 35  is an enlarged planar view of a second display section of the calendar mechanism section shown in  FIG. 33 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     (First Embodiment) 
     A first embodiment in which the present invention has been applied to a pointer type electronic wristwatch will hereinafter be described with reference to  FIG. 1  to  FIG. 15A ,  FIG. 15B , and  FIG. 15C . 
     The electronic wristwatch includes a wristwatch case  1  (device case), as shown in  FIG. 1 . A timepiece module  2  is stored within the wristwatch case  1 . The timepiece module  2  includes a timepiece mechanism section (not shown) that indicates the time by moving hands  3  (e.g. a second hand, a minute hand, and an hour hand) and also includes a calendar mechanism section  4  that displays the date, as shown in  FIG. 2 . 
     The timepiece mechanism section transmits the rotation of a timepiece stepper motor to hand wheels (e.g. a second hand wheel, a minute hand wheel, and an hour hand wheel) by a gear train mechanism, thereby rotating the hand wheels. As a result, the hands  3  attached to a hand shaft of the hand wheels are moved and the time is indicated (not shown). In addition, the calendar mechanism section  4  includes a first display wheel  5  and a second display wheel  6 , and thereby displays the date, as shown in  FIG. 2 . 
     The first display wheel  5  of the calendar mechanism section  4  is formed into a ring shape where a circular hole  5   a  is provided in a center portion of first display wheel  5 , as shown in  FIG. 2 ,  FIG. 4A , and  FIG. 4B . The second display wheel  6  is formed into a circular shape and rotatably placed within the circular hole  5   a  of the first display wheel  5 , as shown in  FIG. 2 ,  FIG. 3 ,  FIG. 5A ,  FIG. 5B , and  FIG. 5C . In this structure, first date display sections  7  (first display sections) are circularly provided on the top surface of the first display wheel  5  where the first date display sections  7  are numerals 0 to 9 standing for the first digit of the date, as shown in  FIG. 2 . Second date display sections  8  (second display sections) are circularly provided at a predetermined interval (e.g. at a 90 degree interval) on the top surface of the second display wheel  6  where the second date display sections  8  are numerals 1 to 3 standing for the second digits of the date. 
     The first display wheel  5  and the second display wheel  6  are rotatably placed on a housing  10  of the timepiece module  2 , as shown in  FIG. 3 . The first display wheel  5  is rotated by a calendar stepper motor  11  which is a driving section dedicated to the calendar mechanism section  4 , as shown in  FIG. 2 . In other words, the first display wheel  5  is rotated by that the rotation of the calendar stepper motor  11  is transmitted to the first display wheel  5  via a transmitting wheel  12 . 
     In this structure, the calendar stepper motor  11  includes a stator  11   a  around which a coil is wound and a rotor  11   b  that is rotated by a magnetic field generated in the stator  11   a , as shown in  FIG. 2 . The rotor  11   b  rotates in the forward direction and the reverse direction. The transmitting wheel  12  rotates by meshing with the pinion of the rotor  11   b  of the calendar stepper motor  11 . The first display wheel  5  rotates by that the teeth section  5   b  provided on the outer peripheral portion of first display wheel  5  meshes with a pinion  12   a  of the transmitting wheel  12 . 
     The first display wheel  5  and the second display wheel  6  include a rotating section  13  that rotates only the first display wheel  5  in the forward direction when the first display wheel  5  rotates in the forward direction, and rotates the second display wheel  6  in the reverse direction together with the first display wheel  5  when the first display wheel  5  rotates in the reverse direction, as shown in  FIG. 3  to  FIG. 5A ,  FIG. 5B , and  FIG. 5C . The rotating section  13  has first clutch teeth  14  that are provided in the inner peripheral portion of the circular hole  5   a  of the first display wheel  5 , and second clutch teeth  15  that are provided in the outer peripheral portion of the second display wheel  6  and meshed with the first clutch teeth  14 , as shown in  FIG. 7  and  FIG. 8 . 
     The first clutch teeth  14  and the second clutch teeth  15  are coupled with each other in the up/down direction, as shown in  FIG. 3 . In other words, the first clutch teeth  14  are provided in the upper inner peripheral portion of the circular hole  5   a  of the first display wheel  5  such that the first clutch teeth  14  project inwards. The second clutch teeth  15  are provided in the lower outer peripheral portion of the second display wheel  6  such that the second clutch teeth  15  project outwards. As a result, the first clutch teeth  14  are placed on the upper side of the second clutch teeth  15  such that the first clutch teeth  14  are coupled with the second clutch teeth  15 . 
     The first clutch teeth  14  have sliding surfaces  14   a  and pressing surfaces  14   b , as shown in  FIG. 7  and  FIG. 8 . The sliding surface  14   a  is gently inclined upward to the forward-rotation direction (counter-clockwise direction) of the first display wheel  5 . The pressing surface  14   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  14   a  positioned in the reverse-rotation direction (clockwise direction) of the first display wheel  5 . In a similar manner, the second clutch teeth  15  have sliding surfaces  15   a  and pressing surfaces  15   b . The sliding surface  15   a  is gently inclined upward to the forward-rotation direction of the first display wheel  5 . The pressing surface  15   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  15   a  positioned in the reverse-rotation direction of the first display wheel  5 . 
     Accordingly, when the first display wheel  5  rotates in the forward direction (counter-clockwise direction), the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other, whereby the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, as shown in  FIG. 10A  and  FIG. 10B . As a result, the rotating section  13  rotates only the first display wheel  5  in the forward direction. 
     Whereas when the first display wheel  5  rotates in the reverse direction (clockwise direction), the pressing surfaces  14   b  of the first clutch teeth  14  and the pressing surfaces  15   b  of the second clutch teeth  15  come in contact with and presses against each other, as shown in  FIG. 11A  and  FIG. 11B . As a result, the rotating section  13  rotates the second display wheel  6  in the reverse direction together with the first display wheel  5  in a state where the first clutch teeth  14  and the second clutch teeth  15  are meshed. 
     In this structure, a dial  16  is placed above the first display wheel  5  and the second display wheel  6 , as shown in  FIG. 3 . The dial  16  is provided with a display window section  16   a  positioned on the 3 o&#39;clock side, where one of the first date display sections  7  and one of the second date display sections  8  respectively correspond to the display window section  16   a , as shown in  FIG. 2 . Accordingly, the first clutch teeth  14  and the second clutch teeth  15  are respectively formed into a predetermined length into which the length of the display window section  16   a  of the dial  16  in the rotation direction is equally divided, such as about ¼ of the length of the display window section  16   a.    
     In other words, the first clutch teeth  14  and the second clutch teeth  15  are respectively formed such that the length between each tooth (pitch) in the rotation direction of the first display wheel  5  is a predetermined length into which the length of the display window section  16   a  in the rotation direction is equally divided, such as about ¼ of the length of the display window section  16   a , as shown in  FIG. 8 . As a result, a predetermined number of the first clutch teeth  14  and the second clutch teeth  15  (e.g. four teeth) are respectively placed corresponding to the display window section  16   a.    
     On the other hand, a brake member  17  is placed between the second display wheel  6  and the housing  10  of the timepiece module  2 , as shown in  FIG. 3 . The brake member  17  is formed into a disk shape that is substantially the same size as the second display wheel  6 , as shown in  FIG. 6A  and  FIG. 6B . The brake member  17  is fixed onto the housing  10  because projecting pins  10   a  on the housing  10  are inserted into the attachment holes  17   a  provided in predetermined positions of the brake member  17 . The brake member  17  is provided with a plurality of flat spring sections  18  that resiliently lift the second display wheel  6  upward and resiliently press the second clutch teeth  15  against the first clutch teeth  14 . 
     The plurality of flat spring sections  18  are provided in four portions of the brake member  17  positioned on the 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, and 9 o&#39;clock sides in an inclined state where each of the plurality of the flat spring sections  18  is bent obliquely upward in the reverse-rotation direction (left side in  FIG. 6B ) of the first display wheel  5 , as shown in  FIG. 6A  and  FIG. 6B . Each of the plurality of flat spring sections  18  engageably or disengageably locks with each of a plurality of sloped recessing sections  20  provided in four portions on the undersurface of the second display wheel  6  positioned on the 12 o&#39;clock, 3 o&#39;clock, 6 o&#39;clock, and 9 o&#39;clock sides, as shown in  FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 9A ,  FIG. 9B , and  FIG. 9C . 
     Each of the plurality of sloped recessing sections  20  has a sloped surface  20   a  and a contact surface  20   b , as shown in  FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 9A ,  FIG. 9B , and  FIG. 9C . The sloped surface  20   a  is bent obliquely upward in the reverse-rotation direction (left side in  FIG. 5C ) of the first display wheel  5 . The contact surface  20   b  is provided at a substantially right angle in the end portion of the sloped surface  20   a  positioned in the reverse-rotation direction of the first display wheel  5 . The sloped recessing section  20  is configured as follows when the second display wheel  6  rotates in response to the forward rotation of the first display wheel  5 , the tip portions of the flat spring sections  18  move along the sloped surface  20   a , thereby coming in contact with the contact surface  20   b ; when the second display wheel  6  rotates in response to the reverse rotation of the first display wheel  5 , the tip portions of the flat spring sections  18  move along the sloped surfaces  20   a , thereby disengaging. 
     Accordingly, the brake member  17  is configured as follows: when the first display wheel  5  rotates in the forward direction, the tip portions of the flat spring sections  18  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  6  in response to the rotation of the second display wheel  6 , thereby coming in contact with and being locked by the contact surfaces  20   b  of the sloped recessing sections  20 . As a result, the rotation of the second display wheel  6  is prevented, as shown in  FIG. 10A ,  FIG. 10B , and  FIG. 10C . 
     In addition, the brake member  17  is configured as follows in the state where the rotation of the second display wheel  6  is prevented by the flat spring sections  18 , the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other in response to the forward rotation of the first display wheel  5 . When the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, the flat spring sections  18  are pressed downward by the second display wheel  6 . As a result, the flat spring sections  18  are resiliently deformed in the up/down direction, and the first clutch teeth  14  and the second clutch teeth  15  become sequentially unmeshed, as shown in  FIG. 10A ,  FIG. 10B , and  FIG. 10C . 
     Furthermore, the brake member  17  is configured as follows when the first display wheel  5  rotates in the reverse direction, the tip portions of the flat spring sections  18  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  6  in response to the rotation of the second display wheel  6 , thereby disengaging from within the sloped recessing sections  20 . As a result, the rotation restriction on the second display wheel  6  are released and the second display wheel  6  rotates in the reverse direction together with the first display wheel  5 , as shown in  FIG. 11A ,  FIG. 11B , and  FIG. 11C . 
     Next, a circuit configuration of the pointer type electronic wristwatch will be described with reference to the block diagram in  FIG. 12 . 
     The pointer type electronic wristwatch includes a timepiece driving system  25  that drives the hands  3  (e.g. the second hand, the minute hand, and the hour hand), and a calendar driving system  26  that changes the date. The timepiece driving system  25  includes a timepiece stepper motor  27  that drives the hands  3  via a timepiece gear train  28 . The calendar driving system  26  includes the calendar stepper motor  11  that drives the first display wheel  5  via the transmitting wheel  12 . 
     In addition, the pointer type electronic wristwatch includes: a control section  30  that performs overall integrated control of the timepiece with a Central Processing Unit (CPU) and the like built therein; a Random Access Memory (RAM)  31  that provides the CPU of the control section  30  with a work memory space; and a Read-Only Memory (ROM)  32  that stores therein various programs executed by the CPU of the control section  30 , initial setting data, and the like. 
     Furthermore, the pointer type electronic wristwatch includes: an oscillation circuit  33  that generates and outputs an oscillation signal of a fixed frequency; a divider circuit  34  that divides the oscillation signal inputted from the oscillation circuit  33  and generates a reference frequency signal for hand movement which is used for time display, for example; a switch section  35  that converts an operation performed by a user into an electrical signal and outputs the electrical signal to the control section  30 ; and a first drive circuit  36  and a second drive circuit  37  that respectively drive the timepiece stepper motor  27  and the calendar stepper motor  11  by outputting a drive pulse in response to the control signals from the control section  30 . 
     The control section  30  performs clocking processing for keeping the time and the following processing: setting a pulse width and a voltage value of a drive pulse, based on time data acquired by the clocking processing and an input signal from the switch section  35  etc.; and then making the first and second drive circuits  36  and  37  output the drive pulse to the timepiece stepper motor  27  and the calendar stepper motor  11 , respectively. 
     The first drive circuit  36  outputs a drive pulse to drive the timepiece stepper motor  27  that moves the hands  3 . The second drive circuit  37  outputs a drive pulse to drive the calendar stepper motor  11  that rotates the first display wheel  5 . A signal length and a voltage value of each of these drive pulses is set based on instructions from the control section  30 . In response to each of these drive pulses, the amount of current sent to the timepiece stepper motor  27  and the calendar stepper motor  11  changes, respectively. 
     Next, operation procedures for driving the timepiece drive system  25  and the calendar drive system  26  in the pointer type electronic wristwatch will be described with reference to an operation flow shown in  FIG. 13 , where  FIG. 13  is a diagram of the procedures in control processing performed by the CPU of the control section  30 . 
     The control processing is interrupt processing that is started by the CPU of the control section  30  in response to a 1 Hz signal inputted from the divider circuit  34  to the control section  30 . When the interrupt processing is invoked and started at the drive timing of the hands  3 , the CPU performs the clocking processing of Step S 1 . 
     In other words, the CPU updates the current time data by adding one second to the current time data stored in the RAM  31 . When the processing of CPU proceeds to Step S 2 , the CPU instructs the first drive circuit  36  so that the first drive circuit  36  supplies a drive pulse to the time piece stepper motor  27 , whereby the timepiece stepper motor  27  is rotated by one step. Then, the rotation of the timepiece stepper motor  27  is transmitted to the hands  3 , and the hands  3  are moved. As a result, the time is indicated. When the processing of the CPU proceeds to Step S 3 , the CPU performs date change processing to update the date and then ends the operation flow. 
     Next, operation procedures of the date change processing for driving the calendar driving system  26  and changing the date will be described with reference to the operation flow shown in  FIG. 14 . 
     When the date change processing is started, the CPU judges at Step S 10  whether or not today (the current day) is the end of the month. At this time, when judged that today is not the end of the month, the processing of the CPU proceeds to Step S 11  and then the CPU judges whether or not the second digit of the date will change on the following day (tomorrow). When judged that the second digit will not change, the processing of the CPU proceeds to Step S 12  and then the CPU judges whether or not the time is 23:59:50. 
     At this time, when judged that the time is not 3:59:50, the CPU returns to the control processing in the main flow and waits until the time is 23:59:50. When judged at Step S 12  that the time is 23:59:50, the processing of the CPU proceeds to Step S 13  and then the CPU instructs the second drive circuit  37  to output a forward-rotation drive pulse to the calendar stepper motor  11 . As a result, the calendar stepper motor  11  is rotated in the forward direction and then the first display wheel  5  is rotated in the forward direction. At this time, the first display wheel  5  is rotated in the forward direction by an amount equivalent to one day of the date, such as by four teeth of the first clutch teeth  14 . 
     As a result, the CPU updates the one of the first date display sections  7 , which is provided on the first display wheel  5  and stands for the first digit, corresponding to the display window section  16   a  of the dial  16 , and returns to the control processing in the main flow. At this time, the second display wheel  6  does not rotate even when the first display wheel  5  rotates. In other words, when the first display wheel  5  rotates in the forward direction, the tip portions of the flat spring sections  18  of the brake member  17  come in contact with the contact surfaces  20   b  of the sloped recessing sections  20  of the second display wheel  6 , and the rotation of the second display wheel  6  is prevented, as shown in  FIG. 10C . 
     Therefore, the sliding surfaces  14   a  of the first clutch teeth  14  of the first display wheel  5  and the sliding surfaces  15   a  of the second clutch teeth  15  of the second display wheel  6  slide against each other, and the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, as shown in  FIG. 10B . At this time, the first clutch teeth  14  and the second clutch teeth  15  become sequentially unmeshed while the flat spring sections  18  of the brake member  17  are pressed downward and resiliently deformed by the second display wheel  6 . 
     As a result, only the first display wheel  5  rotates in the forward direction, and the one of the first date display sections  7 , which stands for the first digit of the date, corresponding to the display window section  16   a  of the dial  16  is changed by one day, whereby the date is updated. At this time, the second display wheel  6  idles, and the one of the second date display section  8 , which stands for the second digit of the date, maintains its current state. 
     When judged at Step S 11  that the second digit of the date will change on the following day, the processing of the CPU proceeds to Step S 14  and then the CPU judges whether or not the time is 23:59:50. At this time, when judged that the time is not 23:59:50, the CPU returns to the control processing in the main flow and waits until the time is 23:59:50 When judged at Step S 14  that the time is 23:59:50, the processing of the CPU proceeds to Step S 15  and then the CPU instructs the second drive circuit  37  to output a reverse-rotation drive pulse to the calendar stepper motor  11 . As a result, the calendar stepper motor  11  is rotated in the reverse direction. 
     And then, the first display wheel  5  is rotated in the reverse direction, and whereby the second display wheel  6  is rotated in the reverse direction together with the first display wheel  5  by the reverse rotation of the first display wheel  5 . As a result, the one of the second date display sections  8  standing for the second digit is updated. At this time, the first display wheel  5  rotates in the reverse direction by an amount equivalent to an interval among the second date display sections  8  provided on the second display wheel  6 , such as by 14 teeth of the first clutch teeth  14 . As a result, the one of the second date display sections  8  standing for the second digit is updated. In other words, when the first display wheel  5  rotates in the reverse direction, the tip portions of the flat spring sections  18  of the brake member  17  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  6  and are disengaged from the sloped recessing sections  20 , whereby the rotation restriction on the second display wheel  6  is released, as shown in  FIG. 11C . 
     As a result, the pressing surfaces  14   b  of the first clutch teeth  14  of the first display wheel  5  and the pressing surfaces  15   b  of the second clutch teeth  15  of the second display wheel  6  come in contact with each other, and the first clutch teeth  14  and the second clutch teeth  15  become meshed, as shown in  FIG. 11B . In this state, the second display wheel  6  rotates in the reverse direction together with the first display wheel  5 . At this time, the first display wheel  5  rotates in the reverse direction by a predetermined angle, and whereby the one of the first date display sections  7 , which stands for the first digit, corresponding to the display window section  16   a  of the dial  16  is reversed such as by three days earlier. In addition, the second display wheel  6  rotates together with the first display wheel  5 , and whereby the one of the second date display sections  8 , which stands for the second digit, corresponding to the display window section  16   a  of the dial  16  is forwarded by an interval among the second date display sections  8 . 
     When the one of the second date display sections  8 , which is provided on the second display wheel  6  and stands for the second digit, is changed and updated as described above, the processing of the CPU proceeds to Step S 16  and then the CPU instructs the second drive circuit  37  to output a forward-rotation drive pulse to the calendar stepper motor  11 . As a result, the calendar stepper motor  11  is rotated in the forward direction. And then, the first display wheel  5  is rotated in the forward direction by an amount equivalent to the number of days required to update the one of the first date display sections  7 , such as by 18 teeth of the first clutch teeth  14 . 
     In other words, at Step S 15 , the first display wheel  5  has been rotated in the reverse direction and reversed by three days earlier, such as by an amount equivalent to 14 teeth of the first clutch teeth  14 . Accordingly, the first display wheel  5  is rotated in the forward direction by the same amount as the first display wheel  5  was rotated in the reverse rotation, and is then further rotated in the forward direction by an amount equivalent to one day, such as by four teeth of the first clutch teeth  14 . At this time as well, the second display wheel  6  idles, and the one of the second date display sections  8  standing for the second digit of the date maintains its current state. As a result, the one of the first date display sections  7  and the one of the second date display sections  8  respectively corresponding to the display window section  16   a  of the dial  16  are changed and updated, where the one of the first date display sections  7  is provided on the first display wheel  5  and stand for the first digit of the date, and the one of the second date display sections  8  is provided on the second display wheel  6  and stand for the second digit of the date. And then, the CPU returns to the control processing in the main flow. 
     When judged at Step S 10  that today is the end of the month, the processing of the CPU proceeds to Step S 17  and then the CPU judges whether or not the time is 23:59:50. At this time, when judged that the time is not 23:59:50, the CPU returns to the control processing in the main flow and waits until the time is 23:59:50. When judged at Step S 17  that the time is 23:59:50, the processing of the CPU proceeds to Step S 18  and then the CPU instructs the second drive circuit  37  to output a reverse-rotation drive pulse to the calendar stepper motor  11 . As a result, the calendar stepper motor  11  is rotated in the reverse direction. 
     And then, the first display wheel  5  is rotated in the reverse direction, and the second display wheel  6  is rotated by the reverse rotation of the first display wheel  5 . As a result, the one of the second date display sections  8 , which is provided on the second display wheel  6  and stands for the second digit, corresponding to the display window section  16   a  of the dial  16  is updated. At this time, the first display wheel  5  is rotated in the reverse direction and whereby the second display wheel  6  is rotated until a section representing “0” among the second date display sections  8 , i.e. a blank section intermediately located between “3” (30th) and “1” (10th), corresponds to the display window section  16   a  of the dial  16 . 
     For example, when today is February 29th (leap year) as shown in  FIG. 15A , the second display wheel  6  is rotated by the reverse rotation of the first display wheel  5  and whereby the one of the second date display sections  8 , which is provided on the second display wheel  6  and stands for the second digit, corresponding to the display window section  16   a  of the dial  16  (i.e. “2” (20th)) changes to the blank section, as shown in  FIG. 15B . At this time, the first display wheel  5  rotates in the reverse direction by 180 degrees, and “4” (4th) of the first date display sections  7 , which is provided on the first display wheel  5  and stands for the first digit corresponds to the display window section  16   a  of the dial  16 . 
     Then, when the one of the second date display sections  8 , which is provided on the second display wheel  6  and stands for the second digit is changed, the processing of the CPU proceeds to Step S 19  and then the CPU instructs the second drive circuit  37  to output a forward-rotation drive pulse to the calendar stepper motor  11 . As a result, the calendar stepper motor  11  rotated in the forward direction. At this time, the first display wheel  5  has been rotated in the reverse direction by 180 degrees at Step S 18 . Accordingly, the first display wheel  5  is rotated in the forward direction by the same amount as the first display wheel  5  was rotated in the reverse rotation, and is then further rotated in the forward direction by an amount equivalent to the number of days required to update the one of the first date display sections  7 , such as by eight teeth of the first clutch teeth  14 . 
     In the example shown in  FIG. 15B , “4” (4th) of the first date display sections  7 , which is provided on the first display wheel  5  and stands for the first digit, has corresponded to the display window section  16   a  of the dial  16 . Accordingly, the one of the first date display sections  7  standing for the first digit (i.e. “4”) changes to “9” when the first display wheel  5  is rotated in the forward direction by 180 degrees. Then, the first display wheel  5  is further rotated in the forward direction by an amount equivalent to two days, such as by eight teeth of the first clutch teeth  14 . At this time, the one of the first date display sections  7 , which stands for the first digit, corresponding to the display window section.  16   a  of the dial  16  (i.e. “9”) changes via “0” to by the forward rotation of the first display wheel  5 , as shown in  FIG. 15C . 
     As a result, “1” of the first date display sections  7  for the first digit corresponds to the display window section  16   a  of the dial  16 , and whereby the date is changed. At this time as well, the second display wheel  6  idles, and the one of the second date display sections  8  standing for the second digit of the date remains the blank section. Therefore, the date corresponding to the display window section  16   a  of the dial  16  becomes “1”. As described above, the date corresponding to the display window section  16   a  of the dial  16  is updated, and then the CPU returns to the control processing in the main flow. 
     As described above, the calendar mechanism section  4  that is the display apparatus of an electronic wristwatch includes: &lt;CLAIM  1 &gt; the first display wheel  5  that has the first date display section  7 ; the second display wheel  6  that has the second date display section  8 ; the calendar stepper motor  11 , a driving section, that rotates in the forward direction and the reverse direction, and rotates the first display wheel  5  in the forward direction and the reverse direction; and the rotating section  13  that rotates only the first display wheel  5  in the forward direction when the first display wheel  5  is rotated in the forward direction, and rotates the second display wheel  6  in the reverse direction together with the first display wheel  5  when the first display wheel  5  is rotated in the reverse direction. Therefore, the structure can be simplified, and the respective numerals of the first date display sections  7  and the second date display sections  8  can be easily and optimally changed and updated merely by the forward rotation and the reverse rotation of just one calendar stepper motor  11 . 
     In other words, in the calendar mechanism section  4  of an electronic wristwatch, the calendar stepper motor  11 , which is a driving section, is rotated in the forward direction and whereby the first display wheel  5  is rotated in the forward direction. As a result, a numeral of the first date display sections  7  can be changed. In addition, the rotating section  13  enables only the first display wheel  5  to rotate in the forward direction. As a result, a numeral of the second date display sections  8  can maintain its current state. Whereas, the calendar stepper motor  11  is rotated in the reverse direction and whereby the first display wheel  5  is rotated in the reverse direction. As a result, the rotating section  13  enables the second display wheel  6  to rotate in the reverse direction together with the first display wheel  5 , and a numeral of the second date display sections  8  can be changed and updated. 
     As described above, the calendar mechanism section  4  is a simple structure that merely has the rotating section  13 . Furthermore, by the forward rotation and the reverse rotation of just one calendar stepper motor  11 , the respective numeral of the first date display section  7  and the second date display section  8  can be easily and appropriately changed. In addition, date display can be about three times as large as existing date displays because the first date display section  7  is provided on the first display wheel  5  and the second date display section  8  is provided on the second display wheel  6 . As a result, visibility of date display can be improved. 
     In this structure, the rotating section  13  includes the first clutch teeth  14  that are provided on the first display wheel  5 , and the second clutch teeth  15  that are provided on the second display wheel  6  and meshed with the first clutch teeth  14 . The first clutch teeth  14  and the second clutch teeth  15  are coupled with each other in the up/down direction, in this state, when the first display wheel  5  is rotated in the forward direction, the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, whereby only the first display wheel  5  rotates in the forward direction. Whereas, when the first display wheel  5  is rotated in the reverse direction, the first clutch teeth  14  and the second clutch teeth  15  are meshed and rotated, whereby the second display wheel  6  rotates in the reverse direction together with the first display wheel  5 . As a result, a numeral of the first date display sections  7  can be changed by the forward rotation of the first display wheel  5 . Whereas, a numeral of the second date display sections  8  provided on the second display wheel  6  can maintain its current state because only the first display wheel  5  can be rotated in the forward direction. Furthermore, the second date display sections  8  provided on the second display wheel  6  can be changed by the reverse rotation of the first display wheel  5 . 
     In other word, when the first display wheel  5  rotates in the forward direction, the first clutch teeth  14  and the second clutch teeth  15  becomes unmeshed, whereby only the first display wheel  5  can rotate in the forward direction. As a result, a numeral of only the first date display sections  7  provided on the first display wheel  5  can be changed, and a numeral of the second date display sections  8  provided on the second display wheel  6  can maintain its current state. Whereas, when the first display wheel  5  rotates in the reverse direction, the first clutch teeth  14  can be meshed and rotated with the second clutch teeth  15 . As a result the second display wheel  6  can be rotated in the reverse direction together with the first display wheel  5 . Therefore, a numeral of the second date display sections  8  of the second display wheel  6  can be unfailingly changed. 
     In addition, in the calendar mechanism section  4 , the first clutch teeth  14  and the second clutch teeth  15  of the rotating section  13  respectively have: the sliding surfaces  14   a  and the sliding surfaces  15   a  that are gently inclined towards the forward-rotation direction of the first display wheel  5 ; and the pressing surfaces  14   b  and the pressing surfaces  15   b  that are provided in the end portions of the sliding surfaces  14   a  and the sliding surfaces  15   a  positioned in the reverse-rotation direction of the first display wheel  5 . Therefore, when the first display wheel  5  rotates in the forward direction, the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  can be favorably slid and smoothly unmeshed. 
     In addition, in the calendar mechanism section  4 , when the first display wheel  5  rotates in the reverse direction, the pressing surfaces  14   b  of the first clutch teeth  14  and the pressing surfaces  15   b  of the second clutch teeth  15  can come in contact with each other. As a result, the second display wheel  6  can be unfailingly rotated by the rotation of the first display wheel  5 . Therefore, a numeral of the first date display sections  7  of the first display wheel  5  and a numeral of the second date display sections  8  of the second display wheel  6  can be unfailingly and appropriately changed by that the first display wheel  5  is rotated in the forward direction and the reverse direction. 
     In this structure, the first display wheel  5  is formed into a ring shape where the circular hole  5   a  is provided in a center portion of first display wheel  5 . The first clutch teeth  14  are circularly provided in the inner peripheral portion of the circular hole  5   a . The second display wheel  6  is formed into a circular shape and rotatably placed within the circular hole  5   a  of the first display wheel  5 . The second clutch teeth  15  are circularly provided in the outer peripheral portion of the second display wheel  6  such that the second clutch teeth  15  are coupled and meshed with the first clutch teeth  14 . As a result, the first display wheel  5  and the second display wheel  6  can be configured compactly, whereby the whole wristwatch can be more compact and smaller. 
     In addition, in the calendar mechanism section  4 , the brake member  17  is provided for applying a brake on the rotation of the second display wheel  6 , such that the brake member  17  restricts the rotation of the second display wheel  6  when the first display wheel  5  rotates in the forward direction, and that the brake member  17  releases the rotation restriction on the second display wheel  6  when the first display wheel  5  rotates in the reverse direction. Therefore, the second display wheel  6  can be idled and rotated by the forward rotation and the reverse rotation of the first display wheel  5 , respectively. As a result, operation reliability of the second display wheel  6  can be improved. 
     In other words, in the calendar mechanism section  4 , when the first display wheel  5  rotates in the forward direction, the brake member  17  can restrict the rotation of the second display wheel  6 , and prevent the second display wheel  6  from rotating. As a result, only the first display wheel  5  can be rotated, and the second display wheel  6  can be favorably idled. Whereas, when the first display wheel  5  rotates in the reverse direction, the brake member  17  can release the rotation restriction on the second display wheel  6 . As a result, the first clutch teeth  14  of the first display wheel  5  and the second clutch teeth  15  of the second display wheel  6  can be unfailingly meshed, and whereby the second display wheel  6  can be unfailingly rotated in the reverse direction together with the first display wheel  5 . 
     In this structure, the brake member  17  has the flat spring sections  18  that are placed below the second display wheel  6  and resiliently press the second clutch teeth  15  against the first clutch teeth  14 . The flat spring sections  18  is inclined in a state where each of the flat spring sections  18  is bent obliquely upward in the forward-rotation direction of the first display wheel  5 . The sloped tip portions engageably or disengageably locks with the sloped recessing sections  20  provided in the second display wheel  6 . Therefore, the rotation of the second display wheel  6  can be unfailingly restricted when the first display wheel  5  is rotated in the forward direction, whereas the rotation restriction on the second display wheel  6  can be unfailingly released when the first display wheel  5  is rotated in the reverse direction. 
     In other words in the brake member  17 , when the first display wheel  5  rotates in the forward direction, the tip portions of the flat spring sections  18  can be locked with the sloped recessing sections  20  of the second display wheel  6 , and the rotation of the second display wheel  6  can be unfailingly restricted, whereas, when the first display wheel  5  rotates in the reverse direction, the flat spring sections  18  can be resiliently deforms in the up/down direction and disengages from the sloped recessing sections  20 . As a result, the rotation restriction on the second display wheel  6  can be unfailingly released, and the second display wheel  6  can be smoothly rotated in the reverse direction together with the first display wheel  5 . 
     (Second Embodiment) 
     Next, a second embodiment in which the present invention has been applied to an electronic wristwatch will be described with reference to  FIG. 16  to  FIG. 20A ,  FIG. 20B , and  FIG. 20C . Note that sections that are the same as those in the first embodiment shown in  FIG. 1  to  FIG. 15A ,  FIG. 15B , and  FIG. 15C  are given the same reference numerals. 
     In a calendar mechanism section  40  of the electronic wristwatch, a first display wheel  41  and a second display wheel.  42  in the second embodiment have different configurations from those in the first embodiment. Other sections have substantially similar configurations to those in the first embodiment. 
     In other words, the first display wheel  41  is formed into a ring shape where a circular hole  41   a  is provided in the center portion of the first display wheel  41 , as shown in  FIG. 16 . The second display wheel  42  is formed into a circular shape placed adjacent to the outer peripheral portion of the first display wheel  41 . The first display wheel  41  and the second display wheel  42  are rotatably placed on the housing  10  of the timepiece module  2 , as shown in  FIG. 17 . 
     In this structure, the rotation of the calendar stepper motor  11  is transmitted to the first display wheel  41  via the transmitting wheel  12 , whereby the first display wheel  41  is rotated in the forward direction and the reverse direction, as shown in  FIG. 16   e . In other words, inner teeth  41   b  are circularly provided in the inner peripheral portion of the circular hole  41   a  of the first display wheel  41 . As in the case of the first embodiment, the calendar stepper motor  11  includes the stator  11   a  around which a coil is wound, and the rotor  11   b  that is rotated by the magnetic field generated in the stator  11   a . The rotor  11   b  rotates in the forward direction and the reverse direction. 
     The calendar stepper motor  11  is placed corresponding to the circular hole  41   a  of the first display wheel  41 , as shown in  FIG. 16 . As in the case of the first embodiment, the transmitting wheel  12  is meshed and rotated with the pinion of the rotor  11   b  of the calendar stepper motor  11 . The pinion  12   a  of the transmitting wheel  12  is meshed and rotated with the inner teeth  41   b  of the first display wheel  41 . As a result, the first display wheel  41  is rotated in the forward direction and the reverse direction by the calendar stepper motor  11 . 
     In addition, as in the case of the first embodiment, the first display wheel  41  and the second display wheel  42  include the rotating section  13  that rotates only the first display wheel  41  in the forward direction when the first display wheel  41  is rotated in the forward direction, and that rotates the second display wheel  42  in the reverse direction together with the first display wheel  41  when the first display wheel  41  is rotated in the reverse direction. The rotating section  13  has the first clutch teeth  14  that are provided in the outer peripheral portion of the first display wheel  41 , and the second clutch teeth  15  that are provided in the outer peripheral portion of the second display wheel  42  and meshed with the first clutch teeth  14 , as shown in  FIG. 18A  and  FIG. 18B . 
     The first clutch teeth  14  and the second clutch teeth  15  are coupled with each other in the up/down direction, as shown in  FIG. 17 . In other words, the first clutch teeth  14  are provided in the upper outer peripheral portion of the first display wheel  41  such that the first clutch teeth  14  project outwards. The second clutch teeth  15  are provided in the lower outer peripheral portion of the second display wheel  42  such that the second clutch teeth  15  project outwards. As a result, the first clutch teeth  14  are placed on the upper side of the second clutch teeth  15  such that the first clutch teeth  14  are coupled with the second clutch teeth  15  thereon, as in the case of the first embodiment. 
     In this structure as well, the first clutch teeth  14  have sliding surfaces  14   a  and pressing surfaces  14   b , as shown in  FIG. 18B . The sliding surface  14   a  is gently inclined upward to the forward-rotation direction (clockwise direction) of the first display wheel  41 . The pressing surface  14   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  14   a  positioned in the reverse-rotation direction (counter-clockwise direction) of the first display wheel  41 . In a similar manner, the second clutch teeth  15  have sliding surfaces  15   a  and pressing surfaces  15   b . The sliding surface  15   a  is gently inclined upward to the forward-rotation direction of the first display wheel  41 . The pressing surface  15   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  15   a  positioned in the reverse-rotation direction of the first display wheel  41 . 
     Accordingly, when the first display wheel  41  rotates in the forward direction (clockwise direction in  FIG. 16 ) the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other, whereby the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, as shown in  FIG. 19B . As a result, the rotating section  13  rotates only the first display wheel  41  in the forward direction. 
     Whereas, when the first display wheel  41  rotates in the reverse direction (counter-clockwise direction in  FIG. 16 ), the pressing surfaces  14   b  of the first clutch teeth  14  and the pressing surfaces  15   b  of the second clutch teeth  15  come in contact with and press against each other, as shown in  FIG. 20B . As a result, the rotating section  13  rotates the second display wheel  42  in the reverse direction together with the first display wheel  41  in a state where the first clutch teeth  14  and the second clutch teeth  15  are meshed. 
     In this structure as well, the dial  16  is placed above the first display wheel  41  and the second display wheel  42 , as shown in  FIG. 17 . The dial  16  is provided with the display window section  16   a  on a predetermined position, where one of the first date display sections  7  and one of the second date display sections  8  correspond to the display window section  16   a , as shown in  FIG. 16 . Accordingly, the first clutch teeth  14  and the second clutch teeth  15  are respectively formed into a predetermined length into which the length of the display window section  16   a  in the rotation direction of the dial  16  is equally divided, such as about ¼ of the length of the display window section  16   a.    
     In other words, the first clutch teeth  14  and the second clutch teeth  15  are formed such that the length of each tooth (pitch) in the rotation direction of the first display wheel  41  is a predetermined length into which the length of the display window section  16   a  in the rotation direction is equally divided, such as about ¼ of the length of the display window section  16   a , as shown in  FIG. 18B . As a result, a predetermined number of the first clutch teeth  14  and the second clutch teeth  15 , e.g. four teeth, are respectively placed corresponding to the display window section  16   a.    
     On the other hand, the brake member  17  is placed between the second display wheel  42  and the housing  10  of the timepiece module  2 , as in the case of the first embodiment. The brake member  17  is formed into a disk shape that is substantially the same size as the second display wheel  42 , as in the case of the first embodiment. The brake member  17  is fixed onto the housing  10 , as in the case of the first embodiment. The brake member  17  is provided with the plurality of flat spring sections  18  that resiliently lift the second display wheel  42  upward and resiliently press the second clutch teeth  15  against the first clutch teeth  14 . 
     Accordingly, the brake member  17  is configured as follows when the first display wheel  41  rotates in the forward direction, the tip portions of the flat spring sections  18  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  42  in response to the rotation of the second display wheel  42 , thereby coming in contact with and being locked by the contact surfaces  20   b  of the sloped recessing sections  20 . As a result, the rotation of the second display wheel  42  is prevented, as shown in  FIG. 19A ,  FIG. 19B , and  FIG. 19C . 
     In addition, the brake member  17  is configured as follows in the state where the rotation of the second display wheel  42  is prevented by the flat spring sections  18 , the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other in response to the forward rotation of the first display wheel  5 . When the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, the flat spring sections  18  are pressed downward by the second display wheel  42 . As a result, the flat spring sections  18  are resiliently deformed in the up/down direction, and the first clutch teeth  14  and the second clutch teeth  15  becomes sequentially unmeshed, as shown in  FIG. 19A ,  FIG. 19B , and  FIG. 19C . 
     Furthermore, the brake member  17  is configured as follows when the first display wheel  5  rotates in the reverse direction, the tip portions of the flat spring sections  18  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  42  in response to the rotation of the second display wheel  42 , thereby disengaging from within the sloped recessing sections  20 . As a result the rotation restriction on the second display wheel  42  are released and the second display wheel  42  rotates in the reverse direction together with the first display wheel  41 , as shown in  FIG. 20A ,  FIG. 20B , and  FIG. 20G . 
     Next, the mechanism of the calendar mechanism section  40  will be described. 
     First, in the case that today is not the end of the month and the second digit of the date will not change on the following day, when the time reaches 23:59:50, the calendar stepper motor  11  is rotated in the forward direction and then the first display wheel  41  is rotated in the forward direction by an amount equivalent to one day of the date, such as by four teeth of the first clutch teeth  14 . As a result, a numeral of the first date display sections  7 , which is provided on the first display wheel  41  and stands for the first digit, corresponding to the display window section  16   a  of the dial  16  is changed and updated. At this time, the second display wheel  42  does not rotate even when the first display wheel  41  rotates. 
     In other words, when the first display wheel  41  rotates in the forward direction, the tip portions of the flat spring sections  16  of the brake member  17  come in contact with the contact surfaces  20   b  of the sloped recessing sections  20  of the second display wheel  42 , and the rotation of the second display wheel  42  is prevented, as in the case of the first embodiment. Therefore, the sliding surfaces  14   a  of the first clutch teeth  14  of the first display wheel  41  and the sliding surfaces  15   a  of the second clutch teeth  15  of the second display wheel  42  slide against each other, and the first clutch teeth  14  and the second clutch teeth  15  becomes unmeshed. 
     At this time, the first clutch teeth  14  and the second clutch teeth  15  becomes sequentially unmeshed while the flat spring sections  18  of the brake member  17  are pressed downward and resiliently deformed by the second display wheel  42 . As a result, the first display wheel  41  rotates, and a numeral of the first date display sections  7 , which stands for the first digit of the date, corresponding to the display window section  16   a  of the dial  16  is changed and updated. At this time, only the first display wheel  41  rotates in the forward direction, whereby a numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit of the date, maintains its current state. 
     In the case that the second digit of the date changes on the following day, when the time reaches 23:59:50, the calendar stepper motor  11  is rotated in the reverse direction. And then. The first display wheel  41  is rotated in the reverse direction by an amount equivalent to an interval among the second date display sections  8  provided on the second display wheel  42 , such as by 14 teeth of the first clutch teeth  14 . As a result, the second display wheel  42  is rotated, whereby a numeral of the second date display sections  8  for the second digit is changed. In other words, when the first display wheel  41  rotates in the reverse direction, the tip portions of the flat spring sections  18  of the brake member  17  relatively move along the sloped surfaces  20   a  of the sloped recessing sections  20  of the second display wheel  42 , thereby being disengaged from the sloped recessing sections  20 . As a result, the rotation restriction on the second display wheel  42  is released, as shown in  FIG. 20C . 
     Therefore, the pressing surfaces  14   b  of the first clutch teeth  14  of the first display wheel  41  and the pressing surfaces  15   b  of the second clutch teeth  15  of the second display wheel  42  come in contact with each other, and the first clutch teeth  14  and the second clutch teeth  15  become meshed, as shown in  FIG. 20B . In this state, the second display wheel  42  rotates in the reverse direction together with the first display wheel  41 . At this time, the first display wheel  41  rotates in the reverse direction by a predetermined angle, such as 90 degrees, and whereby a numeral of the first date display sections  7 , which stands for the first digit, corresponding to the display window section  16   a  of the dial  16  is reversed, such as by three days earlier. In addition, the second display wheel  42  rotates together with the first display wheel  41 , and a numeral of the second date display sections  8 , which stands for the second digit, corresponding to the display window section  16   a  of the dial  16  is forwarded by an interval among the second date display sections  8   
     In this state, the first display wheel  41  has been rotated in the reverse direction by a predetermined angle, such as 90 degrees, and a numeral of the first date display sections  7  standing for the first digit has been reversed, such as by almost three days earlier. Accordingly, by that the calendar stepper motor  11  is rotated in the forward rotation, the first display wheel  41  is rotated in the forward rotation by the same amount as the first display wheel  41  was rotated in the reverse rotation, and is then further rotated in the forward direction by an amount equivalent to one day, such as four teeth of the first clutch teeth  14 . At this time, only the first display wheel  41  is rotated in the forward direction, and a numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit of the date, maintains its current state. As a result, a numeral of the first date display sections  7  and a numeral of the second date display section  8  corresponding to the display window section  16   a  of the dial  16  are respectively changed and updated, where the numeral of the first date display sections  7  is provided on the first display wheel  41  and stands for the first digit, and the numeral of the second date display section  8  is provided on the second display wheel  42  and stands for the second digit on. 
     Whereas, in the case that today is the end of the month, when the time reaches 23:59:50, the calendar stepper motor  11  is rotated in the reverse direction. And then, the first display wheel  41  is rotated in the reverse direction, and the second display wheel  42  is rotated by the reverse rotation of the first display wheel  42 . As a result, a numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit, corresponding to the display window section  16   a  of the dial  16  is changed. At this time, the first display wheel  41  is rotated in the reverse direction and whereby the second display wheel  42  is rotated such that a section representing “0” among the second date display sections  8 , i.e. a blank section intermediately located between “3” (30th) and “1” (10th), corresponds to the display window section  16   a  of the dial  16 . 
     For example, when today is February 29th (leap year) as in the case of the first embodiment shown in  FIG. 15A , the second display wheel  42  is rotated by the reverse rotation of the first display wheel  41  and whereby a numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit, corresponding to the display window section  16   a  of the dial  16  (i.e. “2” (20th)) changes to the blank section, as shown in  FIG. 15B . At this time, the first display wheel  41  rotates in the reverse direction by 180 degrees, and “4” of the first date display sections  7 , which is provided on the first display wheel  41  and stands for the first digit, corresponds to the display window section  16   a  of the dial  16 . 
     Then, when the numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit, is changed, the calendar stepper motor  11  is rotated in the forward direction. Accordingly, the first display wheel  41  is rotated in the forward direction by 180 degrees and is then further rotated in the forward direction by an amount equivalent to the number of days required to update a numeral of the first date display sections  7 , such as by eight teeth of the first clutch teeth  14 . At this time, the first display wheel  41  has been rotated in the reverse direction by 180 degrees. Accordingly, the first display wheel  41  is rotated in the forward direction by the same amount as the first display wheel  41  was rotated in the reverse rotation, and is then further rotated by an amount equivalent to the number of days required to update a numeral of the first date display sections  7 , such as by eight teeth of the first clutch teeth  14 . 
     In an example shown in  FIG. 15B , “4” of the first date display sections  7 , which is provided on the first display wheel  41  and stands for the first digit, corresponds to the display window section  16   a  of the dial  16 . When the first display wheel  41  is rotated in the forward direction by 180 degrees, “4” of the first date display sections  7  standing for the first digit changes to “9”. And then, the first display wheel  41  is further rotated in the forward direction by an amount equivalent to two days such as by eight teeth of the first clutch teeth  14 . At this time, “9” of the first date display sections  7 , which stands for the first digit corresponding to the display window section  16   a  of the dial  16 , changes via “0” to “1” by the forward rotation of the first display wheel  41 , as shown in  FIG. 15C . 
     Therefore, “1” of the first date display sections  7  for the first digit corresponds to the display window section  16   a  of the dial  16 , and whereby the date is changed and updated. At this time, only the first display wheel  41  rotates in the forward direction, and a numeral of the second date display sections  8 , which is provided on the second display wheel  42  and stands for the second digit of the date, remains the blank section. Therefore, the date corresponding to the display window section  16   a  of the dial  16  becomes “1” 
     As described above, in the calendar mechanism section  40  of the display device of an electronic wristwatch, the calendar stepper motor  11 , which is the driving section, is rotated in the forward direction and whereby the first display wheel  41  is rotated in the forward direction. As a result, a numeral of the first date display sections  7  can be changed and updated, in addition, the rotating section  13  enables only the first display wheel  41  to rotate in the forward direction, and a numeral of the second date display sections  8  provided on the second display wheel  42  can maintain its current state, as in the case of the first embodiment. 
     Whereas, in the calendar mechanism section  40 , when the calendar stepper motor  11  is rotated in the reverse direction and whereby the first display wheel  41  is rotated in the reverse direction. As a result, the rotating section  13  enables the second display wheel  42  to rotate in the reverse direction together with the first display wheel  41 , and a numeral of the second date display sections  8  provided on the second display wheel  42  can be changed and updated by the rotation of the second display wheel  42 , as in the case of the first embodiment. 
     Therefore, the above-described calendar mechanism section  40  is also a simple structure that merely has the rotating section  13 . Furthermore, by the forward rotation and the reverse rotation of the single calendar stepper motor  11 , the respective numerals of the first date display sections  7  and the second date display sections  8  can be easily and appropriately changed as in the case of the first embodiment. In addition, date display can be about three times as large as existing date displays because the first date display section  7  is provided on the first display wheel  41  and the second date display section  8  is provided on the second display wheel  42 , as in the case of the first embodiment. As a result, visibility of date display can be improved. 
     In this structure, the first display wheel  41  is formed into a ring shape (a circular shape) and the first clutch teeth  14  are circularly provided in the outer peripheral portion of the first display wheel  41 . The second display wheel  42  is formed into a circular shape and placed adjacent to the outer peripheral portion of the first display wheel  41 . The second clutch teeth  15  are provided in the outer peripheral portion of the second display wheel  42 , where the second clutch teeth  15  are circularly coupled and meshed with the first clutch teeth  14 . As a result the first display wheel  41  and the second display wheel  42  can be separately mounted to the housing  10  of the timepiece module  2 . Therefore, assembly operability can be improved. 
     (Third Embodiment) 
     Next, a third embodiment in which the present invention has been applied to an electronic wristwatch will be described with reference to  FIG. 21  to  FIG. 24A  and  FIG. 24B . In this structure, sections that are the same as those in the first embodiment shown in  FIG. 1  to  FIG. 15A ,  FIG. 15B , and  FIG. 15C  are given the same reference numerals. 
     In a calendar mechanism section  50  of the electronic wristwatch, a brake member  51  in the third embodiment that applies a brake on the first display wheel  5  and the second display wheel  6  have a different configuration from that in the first embodiment, as shown in  FIG. 21 . Other sections have substantially similar configurations to those in the first embodiment. 
     In other words, the brake member  51  includes: a circular plate  53  (fixed plate) that is resiliently provided and can be eccentrically placed within a circular section  52  provided in the second display wheel  6 ; first saw teeth  54  that are provided in the outer peripheral portion of the circular plate  53 ; and second saw teeth  55  that are resiliently provided in the inner peripheral portion of the circular section  52  of the second display wheel  6  and engageably or disengageably engage with the first saw teeth  54 , as shown in  FIG. 21  to  FIG. 23 . In this structure, the circular plate  53  is slidably placed on the housing  10  in a non-rotating state. 
     For example, an long hole  53   a  is provided in the circular plate  53 , as shown in  FIG. 23 , and  FIG. 24A  and  FIG. 24B . A guide shaft  56  that is provided on the housing  10 , such that the cross-section of the guide shaft  56  is a non-circular shape and the guide shaft  56  is slidably inserted into the long hole  53   a  of the circular plate  53 . A spring member  57  is provided between the guide shaft  56  and the long hole  53   a , such that the spring member  57  resiliently presses a portion of the outer peripheral portion of the circular plate  53  against a portion of the circular section  52  of the second display wheel  6 . 
     In addition, the first saw teeth  54  of the circular plate  53  have sliding surfaces  54   a  and pressing surfaces  54   b , as shown in  FIG. 23 . The sliding surface  54   a  is inclined such that the sliding surface  54   a  gently projects towards the forward-rotation direction (clockwise direction in  FIG. 24A ) of the first display wheel  5 . The pressing surface  54   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  54   a  positioned in the reverse-rotation direction (counter-clockwise direction in  FIG. 24B ) of the first display wheel  5 . 
     In a similar manner, the second saw teeth  55  have sliding surfaces  55   a  and pressing surfaces  55   b , as shown in  FIG. 24A  and  FIG. 24B . The sliding surface  55   a  is inclined such that the sliding surface  55   a  is gently squeezed towards the forward-rotation direction (clockwise direction in  FIG. 24A ) of the first display wheel  5 . The pressing surface  55   b  is provided at a substantially right angle or at an acute angle in the end portion of the sliding surface  55   a  positioned in the reverse-rotation direction (counter-clockwise direction in  FIG. 24B ) of the first display wheel  5 . 
     Accordingly, the brake member  51  is configured as follows when the first display wheel  5  rotates in the forward direction, the circular plate  53  is resiliently displaced to one side (right side in  FIG. 24A ), as shown in  FIG. 24A . As a result, some of the pressing surfaces  54   b  of the first saw teeth  54  and some of the pressing surfaces  55   b  of the second saw teeth  55  presses against each other, and whereby some of the first saw teeth  54  and some of the second saw teeth  55  are meshed and engaged with each other. Therefore, the rotation of the second display wheel  6  is restricted, whereby only the first display wheel  5  is rotated in the forward direction. 
     In addition, the brake member  51  is configured as follows when the first display wheel  5  rotates in the reverse direction, the sliding surfaces  54   a  of the first saw teeth  54  and the sliding surfaces  55   a  of the second saw teeth  55  slide against each other while the circular plate  53  is resiliently displaced between both sides (right and left sides in  FIG. 24B ), and whereby the first saw teeth  54  and the second saw teeth  55  become sequentially unmeshed. Therefore, the second display wheel  6  is rotated in the reverse direction together with the first display wheel  5   
     As described above, the calendar mechanism section  50  of the electronic wristwatch in the third embodiment can achieve the same operation effect as those in the first embodiment. In addition, the brake member  51  is included that applies a brake on the rotation of the second display wheel  6 . As a result, the rotation of the second display wheel  6  is restricted when the first display wheel  5  rotates in the forward direction, and the rotation restriction on the second display wheel is released when the first display wheel  5  rotates in the reverse direction. Accordingly, the second display wheel  6  can be idled and rotated by the forward rotation and the reverse rotation of the first display wheel  5 , as in the case of the first embodiment. Therefore, operation reliability of the second display wheel  6  can be improved. 
     In other words, in the calendar mechanism section  50 , when the first display wheel  5  rotates in the forward direction, the brake member  51  can restrict the rotation of the second display wheel  6 , thereby preventing the second display wheel  6  from rotating. As a result, the second display wheel  6  can be favorably idled. Whereas, when the first display wheel  5  rotates in the reverse direction, the brake member  51  can unfailingly make the first clutch teeth  14  of the first display wheel  5  and the second clutch teeth  15  of the second display wheel  6  be meshed with each other. As a result, the second display wheel  6  can be unfailingly rotated by the rotation of the first display wheel  5 , as in the case of the first embodiment. 
     In this structure, the brake member  51  includes: a circular plate  53  that is resiliently provided and can be eccentrically placed within a circular section  52  provided in the second display wheel  6 ; first saw teeth  54  that are provided in the outer peripheral portion of the circular plate  53 ; and second saw teeth  55  that are resiliently provided in the inner peripheral portion of the circular section  52  of the second display wheel  6  and engageably or disengageably engaged with the first saw teeth  54 . Therefore, when the first display wheel rotates in the forward direction, the rotation of the second display wheel  6  can be unfailingly restricted and only the display wheel  5  can be rotated in the forward direction. Whereas, when the first display wheel  5  rotates in the reverse direction, the rotation restriction on the second display wheel  6  can be reliably and favorably released. 
     In other words in the brake member  51 , when the first display wheel  5  rotates in the forward direction, the first saw teeth  54  of the circular plate  53  can engage with the second saw teeth  55  of the second display wheel  6 . As a result, the rotation of the second display wheel  6  can be unfailingly restricted. Whereas, when the first display wheel  5  rotates in the reverse direction, the first saw teeth  54  and the second saw teeth  55  can be sequentially unmeshed while the circular plate  53  is resiliently displaced. As a result, the rotation restriction on the second display wheel  6  can be unfailingly released, and the second display wheel  6  can be smoothly rotated in the reverse direction together with the first display wheel  5 . 
     According to the above-described third embodiment, the second display wheel  6  is rotatably placed within the circular hole  5   a  of the first display wheel  5 , and the brake member  51  applies a brake on the rotation of the second display wheel  6 . However, the present invention is not limited thereto. As shown in a variation example of  FIG. 25 , the brake member  51  may apply a brake on the rotation of the second display wheel  42  as in the case of the second embodiment where the second display wheel  42  is placed adjacent to the outer peripheral portion of the first display wheel  41 . 
     In addition, according to the above-described first embodiment and third embodiment, the first date display sections  7  standing for the first digit are provided on the first display wheel  5  and the second date display sections  8  standing for the second digit are provided on the second display wheel  6 . However, the present invention is not limited thereto. As shown in a variation example of  FIG. 26 , date display sections  58  standing for the date, from the 1st to the 31st, may be provided on the first display wheel  5  as first display sections. Day-of-the-week display sections  59  standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  6  as second display sections. The present invention is not limited thereto. Month display sections standing for the month, from January to December, may be provided on the first display wheel  5 , and day-of-the-week display sections standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  6  (not shown). According to the above-described configurations, the date, the day of the week, the month, and the like can be freely combined and favorably displayed. 
     Furthermore, according to the above-described second embodiment, the first date display sections  7  standing for the first digit are provided on the first display wheel  41  and the second date display sections  8  standing for the second digit are provided on the second display wheel  42 . However, the present invention is not limited thereto. As shown in another variation example of  FIG. 27 , the date display sections  58  standing for the date, from the 1st to the 31st, may be provided on the first display wheel  41 . The day-of-the-week display sections  59  standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  42 . The present invention is not limited thereto. Month display sections standing for the month, from January to December, may be provided on the first display wheel  41 , and day-of-the-week display sections standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  42  (not shown). In the above-described configurations, the date, the day of the week, the month, and the like can be freely combined and favorably displayed as well. 
     (Fourth Embodiment) 
     Next, a fourth embodiment in which the present invention has been applied to an electronic wristwatch will be described with reference to  FIG. 28  to  FIG. 31 . In this structure as well, sections that are the same as those in the first embodiment shown in  FIG. 1  to  FIG. 15A ,  FIG. 15B , and  FIG. 150  are given the same reference numerals. 
     In a calendar mechanism section  60  of the electronic wristwatch, a first display wheel  61  and a second display wheel  62  in the fourth embodiment have different configurations from those in the first embodiment, where the second display wheel  62  is coupled with the first display wheel  61  thereon. Other sections have substantially similar configurations to those in the first embodiment. 
     The first display wheel  61  is formed into a disk shape, as shown in  FIG. 28  and  FIG. 30 . As in the case of the first embodiment, the first date display sections  7  are circularly provided on the top surface of the first display wheel  61  where the first date display sections  7  are numerals 0 to 9 standing for the first digit of the date. The first display wheel  61  is rotated because the rotation of the calendar stepper motor  11  is transmitted to the first display wheel  61  via a transmitting wheel  12 , as shown in  FIG. 28  and  FIG. 30 . In other words, outer teeth  61   a  are provided on the outer periphery edge of the first display wheel  61  such that the outer teeth  61   a  are meshed and rotated with the pinion  12   a  of the transmitting wheel  12 . The transmitting wheel  12  is rotated in the forward direction and the reverse direction by the rotor  11   b  of the calendar stepper motor  11 , as in the case of the first embodiment. 
     The second display wheel  62  is formed into a disk shape that is slightly smaller than the outer diameter of the first display wheel  61 , as shown in  FIG. 28  and  FIG. 29 . As shown in  FIG. 31 , the second date display sections  8  are provided at a predetermined interval (e.g. at a 90 degree interval) on the top surface of the second display wheel  62  where the second date display sections  8  are numerals 1 to 3 standing for the second digit of the date. Display opening sections  63  are respectively provided in positions adjacent to the second date display sections  8  and a blank section located between “1” (10th) and “3”, as shown in  FIG. 28  and  FIG. 31 . There are four display opening sections  63  provided in the second display wheel  62  at a 90 degree interval where ones of the first date display sections  7  respectively correspond to the display opening sections  63 . 
     In this structure, the dial  16  is placed above the second display wheel  62 , as shown in  FIG. 29 . The dial  16  is provided with the display window section  16   a  positioned on the 12 o&#39;clock side, where one of the first date display sections  7  and one of the second date display sections  8  respectively correspond to the display window section  16   a , as shown in  FIG. 28 . As a result, one of the first date display sections  7  standing for the first digit appears through the display opening section  63  of the second display wheel  62 , and one of the second date display section  8  standing for the second digit appears in the display window section  16   a  of the dial  16 . 
     The first display wheel  61  and the second display wheel  62  include the rotating section  13  that rotates only the first display wheel  61  in the forward direction when the first display wheel  61  rotates in the forward direction, and rotates the second display wheel  62  in the reverse direction together with the first display wheel  61  when the first display wheel  61  rotates in the reverse direction, as shown in  FIG. 28  to  FIG. 31 . The rotating section  13  has the first clutch teeth  14  that are provided in the outer peripheral portion of the first display wheel  61 , and the second clutch teeth  15  that are provided in the outer peripheral portion of the second display wheel  62  and meshed with the first clutch teeth  14 , as in the case of the first embodiment. 
     The first clutch teeth  14  and the second clutch teeth  15  are coupled with each other in the up/down direction, as in the case of the first embodiment. In other words, the first clutch teeth  14  are provided in the upper outer peripheral portion of the first display wheel  61 . The second clutch teeth  15  are provided in the lower outer peripheral portion of the second display wheel  62 . As a result, the first clutch teeth  14  are placed such that the first clutch teeth  14  are coupled with the second clutch teeth  15  thereunder. 
     As a result, when the first display wheel  61  rotates in the forward direction, the rotating section  13  rotates only the first display wheel  61  in the forward direction because the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other, and the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, as in the case of the first embodiment. 
     Whereas, when the first display wheel  61  rotates in the reverse direction, the rotating section  13  rotates the second display wheel  62  in the reverse direction together with the first display wheel  61  in a state where the first clutch teeth  14  and the second clutch teeth  15  are meshed because the pressing surfaces  14   b  of the first clutch teeth  14  and the pressing surfaces  15   b  of the second clutch teeth  15  come in contact with and press against each other, as in the case of the first embodiment. 
     On the other hand, the brake member  17  is placed between the second display wheel  62  and the dial  16 , as shown in  FIG. 29 . The brake member  17  is formed into a disk shape that is substantially the same size as the second display wheel  62 , and is fixed to the dial  16 . The brake member  17  is provided with the plurality of flat spring sections  18  that resiliently press the second display wheel  62  downward and resiliently press the second clutch teeth  15  against the first clutch teeth  14 . 
     The plurality of flat spring sections  18  are provided in three positions of the brake member  17 , at the 3 o&#39;clock, 6 o&#39;clock, and 9 o&#39;clock sides, excluding the 12 o&#39;clock side, such that the plurality of flat spring sections  18  are inclined downward to the forward-rotation direction of the first display wheel  61 , as in the case of the first embodiment. In addition, each of the plurality of flat spring sections  18  engageably or disengageably locks with each of the display opening sections  63  provided in the second display wheel  62 . In this structure, a cut-out portion is provided in a portion of the brake member  17  corresponding to the 12 o&#39;clock position such that the cut-out portion corresponds to the display window section  16   a  of the dial  16 . 
     As a result, when the first display wheel  61  rotates in the forward direction, the tip portions of the flat spring sections  18  relatively move along within the display opening sections  63  of the second display wheel  62  in response to the rotation of the second display wheel  62 , and then come in contact and lock with the edge portions of the display opening sections  63  of the second display wheel  62 . Therefore, the brake member  17  prevents rotation of the second display wheel  62 , as in the case of the first embodiment. 
     In addition, the brake member  17  is configured as follows: in the state where the rotation of the second display wheel  62  is prevented by the flat spring sections  18 , the sliding surfaces  14   a  of the first clutch teeth  14  and the sliding surfaces  15   a  of the second clutch teeth  15  slide against each other in response to the forward rotation of the first display wheel  5 . When the first clutch teeth  14  and the second clutch teeth  15  become unmeshed, the flat spring sections  18  are lifted upward by the second display wheel  62 . As a result, the flat spring sections  18  are resiliently deformed in the up/down direction, and the first clutch teeth  14  and the second clutch teeth  15  become sequentially unmeshed, as in the case of the first embodiment. 
     Furthermore, the brake member  17  is configured as follows when the first display wheel  61  rotates in the reverse direction, the flat spring sections  18  relatively move along within the display window sections  53  of the second display wheel  62  while resiliently deforming in response to the rotation of the second display wheel  62 , and then the tip portions of the flat spring sections  18  are disengaged from within the display opening sections  63  of the second display wheel  62 . As a result, the rotation restriction on the second display wheel  62  is sequentially released, and the brake member  17  rotates the second display wheel  62  in the reverse direction together with the first display wheel  61 , as in the case of the first embodiment. 
     As described above, the calendar mechanism section  60  of the electronic wristwatch in the fourth embodiment can achieve the same operation effect as those in the first embodiment. Furthermore, when the calendar stepper motor  11  can be rotated in the forward direction and whereby the first display wheel  61  rotated in the forward direction, a numeral of the first date display sections  7  can be changed and updated. In addition, the rotating section  13  enables the second display wheel  62  to be idled, whereby a numeral of the second date display section  8  of the second display wheel  62  can maintain its current state. Whereas, when the calendar stepper motor  11  is rotated in the reverse direction and whereby the first display wheel  61  is rotated in the reverse direction, the rotating section  13  enables the second display wheel  62  to rotate in the reverse direction together with the first display wheel  61 , and a numeral of the second date display sections  8  can be changed and updated. 
     Therefore, the calendar mechanism section  60  is a simple structure that merely has the rotating section  13 , as in the case of the first embodiment. Furthermore, by the forward rotation and the reverse rotation of just one calendar stepper motor  11 , the respective numerals of the first date display sections  7  and the second date display sections  8  can be easily and appropriately changed. In addition, date display can be about three times as large as existing date displays because the first date display section  7  is provided on the first display wheel  5  and the second date display section  8  is provided on the second display wheel  6 , as in the case of the first embodiment. As a result, visibility of date display can be improved. 
     In other words, in the calendar mechanism section  60 , the display opening sections  63  are provided in the second display wheel  62  placed above the first display wheel  61  having the first date display sections  7  where ones of the first date display sections  7  respectively correspond to the display opening sections  63 . In addition, one of the display opening sections  63  corresponds to the display window section  16   a  of the dial  16  placed above the second display wheel  62 . As a result, the date can be displayed by a numeral of the second date display sections  8  corresponding to the display window section  16   a  of the dial  16  and a numeral of the first date display sections  7  corresponding to the display opening sections  63  of the second display wheel  62 , where the second date display sections  8  are provided on the second display wheel  62  and stand for the second digit, and the first date display sections  7  are provided on the first display wheel  61  and stand for the first digit. Therefore, date display can be sufficiently larger than existing date displays, and visibility of the date display can be improved, as in the case of the first embodiment. 
     According to the above-described fourth embodiment, numerals 1 (10th) to 3 (30th) of the second date display sections  8  standing for the second digit are provided at a predetermined interval on the second display wheel  62 , and the display opening sections  63  are respectively provided in the four positions adjacent to the numerals of the second date display sections  8  and the blank section located between “1” (10th) and “3” (30th). However, the present invention is not limited thereto. For example, the present invention may be configured as a variation example shown in  FIG. 32 . 
     In other words, as shown in the variation example of  FIG. 32 , numerals “1” (10th), “2” (20th), “30” (30th), and “31” (31st) of the second date display section  8 , which are provided on the second display wheel  62  and stand for the second digit, are provided at a predetermined interval. The display opening sections  63  are respectively provided in three positions adjacent to the numeral displays “1” (10th), “2” (20th) of the second date display section  8  and a blank section positioned between “1” (10th) and “31” (31st). The configuration of the above-described variation example can achieve the same operation effect as that of the fourth embodiment. 
     In addition, according to the above-described fourth embodiment, the first date display sections  7  standing for the first digit are provided on the first display wheel  61 , and the second date display sections  8  standing for the second digit are provided on the second display wheel  62 . However, the present invention is not limited thereto. As shown in variation examples of  FIG. 33  to  FIG. 35 , month display sections  64  standing for the months, from January to December, may be provided on the first display wheel  61  as first display sections, and day-of-the-week display sections  65  standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  62  as second display sections. In the above-described configurations, the month and the day of the week can be favorably displayed as well as in the fourth embodiment. 
     In addition, the present invention is not limited to the above-described fourth embodiment and the variation examples. For example, date display sections standing for the dates, from the 1st to the 31st, may be provided on the first display wheel  61 , and day-of-the-week display sections standing for the days of the week, from Monday to Sunday, may be provided on the second display wheel  62 . In the above-described configuration, the date and the day of the week can be freely combined and favorably displayed as well. 
     Still further, according to the above-described first to fourth embodiments and variation examples, the present invention is applied to a pointer type electronic wristwatch. However, the present invention is not necessarily required to be applied to an electronic wristwatch, and can be applied to various types of electronic timepieces, such as travel clocks, alarm clocks, mantelpiece clocks, wall clocks, etc. Moreover, the present invention is not necessarily required to be applied to an electronic timepiece and may be widely applied to various types of equipment, such as a calendar apparatus, an instrument meter, etc. 
     Several embodiments of the present invention are described above. However, the present invention is not limited thereto and includes inventions recited in the scope of claims and scope equivalent thereto. 
     While the present invention has been described with reference to the preferred embodiments, it is intended that the invention be not limited by any of the details of the description therein but includes all the embodiments which fall within the scope of the appended claims.