Patent Publication Number: US-9841733-B2

Title: Electronic timepiece

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/519,718, filed Oct. 21, 2014, which claims priority to Japanese Patent Application No. 2013-245797, filed Nov. 28, 2013, the entire disclosures of which are expressly incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an electronic timepiece. 
     2. Related Art 
     Electronic timepieces that use satellite signals to calculate the current location, and display the time zone at the current location (a geographical area that uses a common standard time), the standard time used in that time zone, and the time difference to UTC (Coordinated Universal Time), are known. JP-A-2009-175044, for example, discloses a wristwatch that has a plurality of hands and a dial on which a map is displayed, and creates an intersection of plural hands on the map to indicate the current location. 
     A wristwatch that shows 39 time zones around the outside of the dial, and indicates the time zone of the current location with a hand, is also described in the July 2013 issue of GoodsPress (Tokuma Shoten, 10 Jul. 2013, pp. 75-81; in Japanese). This wristwatch has a receiver unit that receives satellite signals from a GPS (Global Positioning System) or other navigational satellites, and receives signals from four navigational satellites to acquire location and time information for the current location, set the local time zone, and displays the current local time. 
     However, there are currently 40 different time zones around the world. The electronic timepieces described in JP-A-2009-175044 and the July 2013 issue of GoodsPress are therefore not compatible with all of the time zones used around the world. 
     SUMMARY 
     The present invention is directed to solving at least part of the foregoing problem as described in the embodiments and examples below. 
     An electronic timepiece according to this example has an outside perimeter part disposed around a dial; hands; and a control unit; wherein 40≦60 time zone indicators including time difference information representing the time difference between Coordinated Universal Time (UTC) and the standard time used in each time zone are expressed on the outside perimeter part; and the control unit indicates a specific time zone indicator with the hand. 
     The electronic timepiece according to this example has time zone indicators including time difference information expressed on an outside perimeter part disposed around the dial. An electronic timepiece with a typical analog display has a scale with 60 markers for indicating the hour and minute around the outside of the dial. This scale can be used to express 40 or more time zone indicators including time difference information representing the time difference between Coordinated Universal Time (UTC) and the standard time. The electronic timepiece can therefore indicate the time in time zones (the standard time in a particular time zone) with greater than or equal to 40 and less than or equal to 60 time differences to UTC by the control unit setting hands to a specific time zone indicator (marker) and the time. An electronic timepiece that is compatible with every time zone around the world can therefore be provided. 
     In an electronic timepiece according to another example, the outside perimeter part is at least one of a bezel and a dial ring. 
     In this example, the outside perimeter part is at least one of a bezel around the crystal, and a dial ring around the inside circumference of the crystal. The parts located on the outside perimeter part of the dial in a wristwatch-type electronic timepiece have a comparatively wide display area around the minute and second scale of the dial, and this area can therefore be used to express time zone indicators that are easy to read and contain a lot of information. 
     In an electronic timepiece according to another example, the number of time zone indicators is equal to the number of time zones used around the Earth. 
     In this example, the number of time zone indicators shown on the electronic timepiece is equal to the number of time zones used around the world. For example, by setting time difference information expressing the time difference of the standard time used in 40 different time zones on the scale that shows the hour and minute on the outside perimeter part disposed around the dial, the appropriate time can be displayed in each of the 40 time zones that are used around the world. Furthermore, because up to 60 different time differences can be set, the electronic timepiece according to this example can display the appropriate time in up to 60 different time zones, and can display the appropriate time even if a new region (time zone) using a different standard time than the standard times that are currently used is created. 
     In an electronic timepiece according to another example, the time difference information is expressed by numbers and non-numeric symbols. 
     The electronic timepiece according to this example expresses the time difference information with numbers and non-numeric symbols. As a result, time difference information that is easy to read and contains a lot of information can be expressed in a limited space. 
     In an electronic timepiece according to another example, the time difference information is expressed by a number when the time difference information is an integer value, and by a symbol when the time difference information is not an integer value. 
     This electronic timepiece according to this example expresses the time difference using numbers or non-numeric symbols depending on whether or not the time difference is an integer value. The time difference between UTC and the standard time used in some time zones cannot be expressed by a whole number. In India, for example, a time difference of +5.5 hours (+5 hours 30 minutes) is used. Because space for expressing time difference information is limited in a wristwatch-type electronic timepiece, the number of displayed letters can be reduced by using symbols for non-integer time differences, and time difference information that is easy to read and contains a lot of information can be expressed in a limited space. 
     In an electronic timepiece according to another example, the time zone indicators include the time difference information of UTC+8.75 hours. 
     By setting time difference information for 40 time zones, specifically the 39 time zones with which conventional electronic timepieces are compatible plus a new time zone with a time difference of +8.75 hours (+8 hours 45 minutes), on the scale indicating minutes and seconds on the outside perimeter part disposed around the dial, for example, the electronic timepiece according to this example can indicate the correct time in every time zone around the world. 
     In an electronic timepiece according to another example, the time zone indicators include city name information expressing a name of a representative city using the standard time appropriate to the time difference. 
     The time zone indicators in this example include time difference information expressing the time difference, and city information expressing the name of a representative city in the time zone using the standard time with the same time difference. As a result, the user of the electronic timepiece can easily know the time difference in the representative city from the city information. 
     An electronic timepiece according to another example preferably also has a storage unit that stores location information and time information for the current location obtained from an external signal. Time zone information including information about the time difference contained in the time difference information, and a geographical region that uses the standard time corresponding to the time difference, is stored in the storage unit; and the control unit sets the time zone of the current location based on the location information, the time information, and the time zone information. 
     An electronic timepiece according to this example can acquire the time zone of the current location and the standard time (current local time) used in that time zone by, for example, receiving external signals from four GPS satellites and comparing the location information calculated from the received signals, the time information, and the time zone information stored in the storage unit. By setting the time zone of the current location, the control unit can display the current time appropriate to the time zone of the current location. 
     An electronic timepiece according to another example preferably enables manually setting the time zone of the current location. 
     Because the electronic timepiece according to this example has a function for setting the time zone manually, the electronic timepiece can be manually set to the correct time zone. For example, when the time zone of the current location is not correctly set in the electronic timepiece because of error in location information near the border of the time zone, this configuration enables manually setting the correct time zone in the electronic timepiece. As a result, the electronic timepiece can display the current local time appropriately to the time zone of the current location. 
     An electronic timepiece according to another example of the invention is compatible with 40≦60 time zones. 
     The electronic timepiece according to this example can display the standard time in 40≦60 time zones. An electronic timepiece that is compatible with every time zone in the world can therefore be provided. 
     Other objects and attainments together with a better understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an application of a GPS system including an electronic timepiece according to the invention. 
         FIG. 2  is a perspective view showing an overview of an electronic timepiece. 
         FIGS. 3A-F  show six different views of the electronic timepiece. 
         FIG. 4  is a section view showing part of the electronic timepiece. 
         FIG. 5  is a plan view from the face of the electronic timepiece. 
         FIG. 6  is a block diagram illustrating the electrical control system of the electronic timepiece. 
         FIG. 7  is a flow chart illustrating the operation of the electronic timepiece. 
         FIG. 8  is a plan view from the face of another example of an electronic timepiece. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A preferred embodiment of the present invention is described below with reference to the accompanying figures. Note that the scale of various layers and parts of the electronic timepiece differ from the actual scale shown in the figures in order to illustrate the layers and parts in a size enabling better recognition and understanding. 
     Preferred Embodiment 
       FIG. 1  illustrates a GPS including an electronic timepiece according to an embodiment of the invention. The basic configuration of the GPS whereby an electronic timepiece operating as a GPS receiver receives RF signals from the GPS satellites to obtain location information and time information for the current location is described first. 
     The electronic timepiece  10  in this embodiment of the invention is a wristwatch that receives RF signals (satellite signals) from GPS satellites  8 , and adjusts the internal time and displays the current time on the opposite side of the wristwatch (the face) as the side of the wristwatch worn in contact with the wrist (the back). 
     The GPS satellites  8  are navigational satellites that orbit the Earth in space on specific orbits, and broadcast a navigation message superimposed on a 1.57542 GHz carrier wave (L1 wave). For brevity below, the 1.57542 GHz carrier wave to which the navigation message is superimposed is referred to as the satellite signal. The satellite signals are right-hand circularly polarized waves. 
     There are presently 31 GPS satellites  8  in orbit (only 4 are shown in  FIG. 1 ), and to identify which of the GPS satellites  8  transmitted the received satellite signal, a unique 1023 chip (1 ms) pattern called a C/A code (Coarse/Acquisition Code) is superimposed by each GPS satellite  8 . Each chip in the C/A code denotes a +1 or −1, and the C/A code appears as a pseudorandom pattern. Therefore, by determining the correlation between the satellite signal and the pattern of each C/A code, the C/A code superimposed in a particular satellite signal can be detected. 
     Each GPS satellite  8  carries an atomic clock, and extremely precise GPS time information that is kept by the atomic clock is embedded in each satellite signal. The slight time difference between the atomic clocks carried by the GPS satellites  8  is measured by a land-based control segment, and a time correction parameter for correcting the particular time difference is included in each satellite signal. 
     The electronic timepiece  10  receives a satellite signal transmitted from one GPS satellite  8 , and sets the internal time of the electronic timepiece  10  to the precise time (time information) obtained using the GPS time information and time correction parameter contained in the received satellite signal. 
     Orbit information identifying the location of the GPS satellite  8  on its orbit is also contained in the satellite signal. The electronic timepiece  10  performs a positioning calculation using the GPS time information and orbit information. This positioning calculation assumes there is a certain amount of error in the internal time of the electronic timepiece  10 . 
     More specifically, in addition to the x, y, z parameters for acquiring the location of the electronic timepiece  10  in three dimensions, the time difference is also an unknown variable. The electronic timepiece  10  therefore generally receives satellite signals transmitted from four or more GPS satellites  8 , and runs the positioning calculation using the GPS time information and orbit information contained in the received satellite signals to determine the location information of the current location. 
     The basic configuration of the electronic timepiece  10  is described next.  FIG. 2  is a perspective view showing the appearance of the electronic timepiece  10 ,  FIGS. 3A-F  show six views of the appearance of the electronic timepiece  10 , and  FIG. 4  is a partial section view showing the configuration of the electronic timepiece  10 . 
     Note that  FIG. 3A  is a plan view of the electronic timepiece from the face side, and  FIG. 3B  is a side view looking from the 3:00 position to the 9:00 position.  FIG. 3C  is a side view looking from the 12:00 position to the 6:00 position.  FIG. 3D  is a side view looking from the 9:00 position to the 3:00 position.  FIG. 3E  is a side view looking from the 6:00 position to the 12:00 position.  FIG. 3F  is a plan view of the back of the electronic timepiece  10 . 
     The electronic timepiece  10  according to this embodiment has a world time function and a chronograph function. 
     As shown in  FIG. 2  and  FIGS. 3A-F , the electronic timepiece  10  has an outside case  30 , a crystal  33 , and a back cover  34 . 
     The outside case  30  includes a ceramic bezel  32  fit to a tubular case member  31  preferably made of metal. A disc-shaped dial  11  is disposed as the time display part through a plastic annular dial ring  40  on the inside circumference side of the ceramic bezel  32 . In this embodiment, the ceramic bezel  32  and the dial ring  40  correspond to the outside perimeter of the dial  11 . 
     Hands  21 ,  22 ,  23  are disposed above the dial  11 . Around the center of the dial  11  are further disposed a round first subdial  70  and hand  71  at 2:00; a round second subdial  80  and hand  81  at 10:00; a round third subdial  90  and hand  91  at 6:00; and a rectangular calendar window  15  at 4:00. The dial  11 , hands  21 ,  22 ,  23 , first subdial  70 , second subdial  80 , third subdial  90 , and calendar window  15  can be seen through the crystal  33 . 
     A button  61  is disposed to the side of the outside case  30  at 8:00 from the center of the dial  11 ; a button  62  is disposed at 10:00; a button  63  is disposed at 2:00; a button  64  is disposed at 4:00; and a crown  50  is disposed at 3:00. When the button  61 , button  62 , button  63 , button  64 , and crown  50  are operated, operating signals corresponding to the specific operation are output. 
     As shown in  FIG. 4 , of the two main openings in the outside case  30 , the opening on the face side of the electronic timepiece  10  is covered by the crystal  33  through the intervening ceramic bezel  32 , and the opening on the back side is covered by the back cover  34  which is preferably metal. 
     Disposed inside the outside case  30  are the dial ring  40  attached to the inside circumference of the ceramic bezel  32 ; an optically transparent dial  11 ; a center arbor  25  that passes through the dial  11 ; the hands  21 ,  22 ,  23  that rotate on the center arbor  25 ; and a drive mechanism  140  that drives the hands  21 ,  22 ,  23 . 
     The center arbor  25  passes through the center of the outside case  30  in plan view, and is disposed on the center axis between the face and back of the timepiece. 
     The dial ring  40  has a flat portion of which the outside edge contacts the inside circumference surface of the ceramic bezel  32  and one surface is parallel to the crystal  33 ; and a beveled portion that slopes toward the dial  11  so that the inside edge contacts the dial  11 . The dial ring  40  is ring-shaped when seen in plan view, and conically shaped (e.g., frusto-conical) when seen in section view. A donut-shaped storage space is formed by the flat portion and the beveled portion of the dial ring  40 , and the inside circumference surface of the ceramic bezel  32 . A ring antenna  110  is housed in this storage space. 
     The antenna  110  has a ring-shaped dielectric base on which a metal antenna pattern is formed by, for example, plating or silver paste printing. The antenna  110  is disposed around the perimeter of the dial  11  and the inside circumference side of the ceramic bezel  32 , is covered by the plastic dial ring  40  and crystal  33 , and can therefore assure good reception. The dielectric in this embodiment is molded from a titanium oxide or other high frequency dielectric material mixed with resin, and enables rendering a small antenna by using the wavelength-shortening effect of the dielectric. 
     The dial  11  is a round disc for indicating the time inside the outside case  30 , is made from plastic or other suitable material, and is disposed inside the dial ring  40  with the hands  21 ,  22 ,  23  between the dial  11  and the crystal  33 . 
     A photovoltaic solar panel  135  is disposed between the dial  11  and the ground plate  125  to which the drive mechanism  140  is attached. The solar panel  135  is a round panel having a plurality of solar cells (photovoltaic elements) that convert light energy to electrical energy connected in series. The solar panel  135  also has a sunlight detection function. Holes through which the center arbor  25 , arbors (not shown in the figure) for the hand  71  of the first subdial  70 , the hand  81  of the second subdial  80 , and the hand  91  of the third subdial  90  pass, and the aperture of the calendar window  15 , are formed in the dial  11 , the solar panel  135 , and the ground plate  125 . 
     The drive mechanism  140  is attached to the ground plate  125 , and is covered on the back side by a circuit board  120 . The drive mechanism  140  has a stepper motor and a wheel train of wheels, and drives the hands  21 ,  22 ,  23  by the stepper motor turning the center arbor  25  through the wheel train. The hand  71  of the first subdial  70 , the hand  81  of the second subdial  80 , and the hand  91  of the third subdial  90  shown in  FIG. 2  and  FIG. 3  have similar drive mechanisms (not shown in the figure) that drive the hands  71 ,  81 ,  91 . 
     The circuit board  120  has a balun  121 , receiver unit (GPS module)  122 , control unit  150 , and a lithium ion or other storage battery  130 . The storage battery  130  is charged by power produced by the solar panel  135 . The circuit board  120  and antenna  110  are connected through an antenna connection pin  115 . The balun  121  is a balanced-unbalanced conversion element that converts balanced signals from the antenna  110  operated with a balanced power supply to unbalanced signals that can be handled by the receiver unit  122 . 
     The antenna  110  is powered through a power supply node, and the antenna connection pin  115  disposed on the back side of the antenna  110  is connected to this power supply node. The antenna connection pin  115  is a metal pin-shaped connector that is disposed to the circuit board  120  and passes through a through-hole formed in the ground plate  125  into the storage space. The circuit board  120  and the antenna  110  inside the storage space are connected to the antenna connection pin  115 . 
     The display function of the electronic timepiece  10  is described next.  FIG. 5  is a plan view of the electronic timepiece  10  from the face side. 
     As shown in  FIG. 5 , a scale dividing the outside circumference into 60 divisions, each of which is subdivided into a ⅕ scale of 5 divisions, is formed around the outside perimeter of the dial  11 . Using this scale, the second hand  21  indicates the seconds of the chronograph function, the minute hand  22  indicates the minute of the internal clock, and the hour hand  23  indicates the hour of the internal clock. The chronograph function can be used by operating button  63  and button  64 . 
     A scale of 60 divisions with numeric markers 10 to 60 at increments of 10 is disposed around the outside of the round first subdial  70  on the dial  11 . The hand  71  of this first subdial  70  uses this scale to indicate the minute of the chronograph function. 
     A scale of 60 divisions with numeric markers 0 to 11 is disposed around the outside of the round second subdial  80  on the dial  11 . The hand  81  of this second subdial  80  uses this scale to indicate the second of the internal clock. 
     The letter Y is disposed to the 52-second position and the letter N is disposed to the 38-second position of the second subdial  80 . These letters are used to indicate the result of satellite signal reception (Y=reception succeeded, N=reception failed), and the satellite signal automatic reception mode (Y=automatic reception is ON, N=automatic reception is OFF). When the operator operates button  62 , the hand  81  jumps to either Y or N according to the result of satellite signal reception. The automatic reception mode can be turned ON/OFF by the operator operating button  61  and button  62  to set the hand  81  to Y or N as desired. When the operator operates button  62  to manually command satellite signal reception by the electronic timepiece  10 , the hand  81  indicates the number of captured satellites. 
     Note that a Y marker is at the 52-second position and an N marker is at the 38-second position in this embodiment, but the invention is not so limited. The Y and N markers are preferably disposed to positions that are easy to see according to the position where the subdial including the reception result display is disposed. 
     The markers around the round third subdial  90  on the dial  11  are described next. Note that the expression “n:00 position” (where n is a desirable natural number) used in the following description of the third subdial  90  denotes the direction (position) on the outside of the circle from the center of the third subdial  90 . 
     A scale of six divisions with numeric markers 0 to 5 is formed on the outside perimeter of the third subdial  90  from 12:00 to 6:00. Using this scale, the hand  91  indicates the hour of the chronograph function. 
     The chronograph function in this embodiment can count time to 5 hours 59 minutes 59 seconds using hands  21 ,  71 ,  91 . 
     The letters DST and an open circle (O) are disposed to the third subdial  90  in the area from 6:00 to 7:00. DST denotes Daylight Savings Time (also known as summer time). These markers are used to indicate if daylight savings time is being used (DST=daylight savings time is in use; O indicates daylight savings time is not in use). The operator can set the DST mode of the electronic timepiece  10  on or off by operating the crown  50  and button  62  to set the hand  91  to DST or O appropriately. 
     A sickle-shaped marker  92  that is wide at the base at 9:00 and narrows to the end at 7:00 is disposed along the outside edge of the third subdial  90  from 7:00 to 9:00. This marker  92  is a power indicator for the storage battery  130  ( FIG. 4 ), and the hand  91  indicates a position at the base, middle, or tip of the marker  92  according to the reserve power in the storage battery  130 . 
     An airplane-shaped marker  93  is disposed in the area from 9:00 to 10:00 on the outside of the third subdial  90 . This airplane marker  93  denotes an in-flight mode. Satellite signal reception is prohibited in some countries by aviation regulations during take-off and landing of an airplane. Satellite signal reception by the electronic timepiece  10  can be stopped by the user operating the button  61  and setting the hand  91  to the airplane marker  93  (in-flight mode). 
     Numeric markers 1 and 4, and a + marker are disposed in the area from 10:00 to 12:00 on the outside of the third subdial  90 . These numbers and marker are used to indicate the satellite signal reception mode. The 1 marker means that the GPS time information was received and the internal time corrected, and the 4+marker means that GPS time information and orbit information were received, and the internal time and time zone described below were corrected. When the operator operates the button  62 , the hand  91  jumps to the 1 or the 4+marker to indicate the reception mode of the satellite signal that was just received by the electronic timepiece  10 . 
     The calendar window  15  is a rectangular opening formed in the dial  11 , and a number can be seen through the calendar window  15 . This number indicates the day value of the current date. 
     The relationship between Coordinated Universal Time (UTC), the time difference, standard time, and the time zone is described next. 
     A time zone denotes a geographical area that uses a common standard time, and there are currently 40 time zones around the world. Each time zone is distinguished by the time difference between the standard time used in the time zone and UTC. Japan, for example, belongs in a time zone using a standard time that is 9 hours ahead of UTC, or UTC+9. The standard time used in each time zone can be obtained from UTC and the time difference to UTC. 
     As described above, a scale divided into 60 minutes and seconds is formed on the dial  11 , and time difference information  45  representing the time difference to UTC is indicated by numbers and non-numeric markers along the time scale on the dial ring  40  surrounding the outside perimeter of the dial  11 . The numeric time difference information  45  denotes the integer value of the time difference, and the non-numeric time difference information  45  denotes a time difference that is not a whole number. The time difference between UTC and the internal time indicated by hands  22 ,  23 ,  81  can be checked by the time difference information  45  indicated by the second hand  21  by operating the crown  50 . 
     By assigning one time difference to one marker on the scale of 60 divisions on the dial  11 , the electronic timepiece  10  can indicate an internal time corresponding to a maximum of 60 different time differences. 
     Note that in this embodiment of the invention the time difference information  45  at the UTC marker denotes Coordinated Universal Time, which is the standard time difference, and the time difference information  45  at the bullet (•) markers denotes time differences that are not whole numbers, but the invention is not so limited and other markers may be used instead. 
     In this embodiment, the time difference information  45  of the bullet (•) marker shown between the numbers 8 and 9 on the dial ring  40  denotes a time difference of +8.75 hours (+8 hours 45 minutes), and means a time zone that uses a standard time of UTC+8.75 hours. Including this standard time, there are currently 40 different time zones around the world, and the time difference in each of these 40 time zones is expressed on the dial ring  40  of the electronic timepiece  10 . The number of time zone indications is preferably 60 or less. If the number exceeds 60, the markers become smaller and readability may become difficult. 
     City markers  35  each representing the name of a major city in the time zone using the standard time corresponding to the time difference of the time difference information  45  denoted on the dial ring  40  is displayed beside the time difference information  45  on the bezel  32  around the dial ring  40 . The city markers  35  in this embodiment of the invention use three-letter codes that are three letter alphabetic abbreviations of the city names. More specifically, LON denotes London, PAR denotes Paris, CAI denotes Cairo, JED denotes Jeddah, DXB denotes Dubai, KHI denotes Karachi, DEL denotes Delhi, DAC denotes Dhaka, BKK denotes Bangkok, BJS denotes Beijing, TYO denotes Tokyo, ADL denotes Adelaide, SYD denotes Sydney, NOU denotes Noumea, WLG denotes Wellington, TBU denotes Nuku&#39;alofa, CXI denotes Christmas Island, MDY denotes Midway Island, HNL denotes Honolulu, ANC denotes Anchorage, LAX denotes Los Angeles, DEN denotes Denver, CHI denotes Chicago, NYC denotes New York, CCS denotes Caracas, SCL denotes Santiago, RIO denotes Rio de Janeiro, FEN denotes Fernando de Noronha, and PDL denotes the Azores. 
     For example, the code TYO represents Tokyo, and that Tokyo uses a standard time of UTC+9 can be easily determined from the number 9 of the time difference information  45  corresponding to this city code displayed on the dial ring  40 . Likewise, the code CXI represents Christmas Island, and that Christmas Island uses a standard time of UTC+14 can be easily determined from the number 14 of the time difference information  45  corresponding to this city code displayed on the dial ring  40 . 
     Note that indication of a representative city name corresponding to the time difference of some time difference information  45  is omitted in this embodiment due to the limited display space and to improve readability. 
     The method of indicating representative city names is also simply one example, and representative city names may be indicated by other methods. The combined indications of the time difference information  45  and city markers  35  are referred to below as time zone indicators  46 . This embodiment of the invention has the same number of time zone indicators  46  as the number of time zones around the world. 
     The electrical configuration of the electronic timepiece  10  is described next. 
       FIG. 6  is a block diagram of the electrical control system of the electronic timepiece. As shown in  FIG. 6 , the electronic timepiece  10  has a control unit  150  having a basic configuration including a CPU (central processing unit)  153 , RAM (random access memory)  154 , and ROM (read-only memory)  155 ; and peripheral devices including a receiver unit  122  (GPS module), an input device  157 , and the drive mechanism  140 . These devices exchange data through a data bus  159 . The input device  157  includes the crown  50 , button  61 , button  62 , button  63 , and button  64  shown in  FIG. 5 . Note that the electronic timepiece  10  also has a rechargeable storage battery  130  ( FIG. 4 ) as a power supply. 
     The receiver unit  122  includes the antenna  110 , processes satellite signals received through the antenna  110 , and acquires GPS time information and location information. The antenna  110  receives the radio waves of satellite signals that are transmitted from a plurality of GPS satellites  8  (see  FIG. 1 ) orbiting the Earth in space on specific orbits and pass through the crystal  33  and dial ring  40  shown in  FIG. 4 . 
     As shown in the figure and similarly to a typical GPS receiver, the receiver unit  122  includes an RF (radio frequency) unit that receives and converts satellite signals transmitted from the GPS satellites  8  ( FIG. 1 ) to digital signals; a baseband unit that executes a reception signal correlation process and demodulates the navigation message; and a data acquisition unit that acquires and outputs the GPS time information and location information (positioning information) from the navigation message (satellite signals) demodulated by the baseband unit. The receiver unit  122  thus functions as a receiver that receives satellite signals transmitted from the GPS satellites  8 , and outputs GPS time information and location information based on the result of reception. 
     The RF unit includes a bandpass filter, PLL circuit, IF filter, VCO (voltage controlled oscillator), ADC (A/D converter), mixer, LNA (low noise amplifier), and IF amplifier. 
     The satellite signal extracted by the bandpass filter is amplified by the LNA, mixed by the mixer with the signal from the VCO, and down-converted to an IF (intermediate frequency) signal. The IF signal mixed by the mixer then passes through the IF amplifier and IF filter, and is converted by the A/D converter to a digital signal. 
     The baseband unit has a local code generator and a correlation unit. 
     The local code generator generates local codes that are the same as the C/A codes used by the GPS satellites  8  for signal transmission. 
     The correlation unit calculates the correlation between the local codes and the reception signal output from the RF unit. If the correlation calculated by the correlation unit equals or exceeds a specific threshold, the C/A code used in the received satellite signal and the local code that was generated match, and the satellite signal can be captured (synchronized). The navigation message can therefore be demodulated by the correlation process using the received satellite signal and a local code. 
     The data acquisition unit acquires the GPS time information and location information from the navigation message demodulated by the baseband unit. The navigation message contains preamble data, the TOW (Time of Week, also called the Z count) of the HOW word, and subframe data. There are five subframes, subframe  1  to subframe  5 , and each subframe contains satellite correction data including a week number value and satellite health data, ephemeris data (detailed orbit information for a particular GPS satellite  8 ), and almanac data (basic orbit information for all GPS satellites  8 ). The data acquisition unit can therefore acquire the GPS time information and navigation information by extracting specific data from the received navigation message. 
     The RAM  154  and ROM  155  are the storage unit of the electronic timepiece  10 . 
     A program run by the CPU  153  and time zone information are stored in ROM  155 . The time zone information is data for managing location information (latitude and longitude) about geographical areas (time zones) using a common standard time, and the difference to UTC. 
     By running a program stored in ROM  155  using RAM  154  as working memory, the CPU  153  performs various calculation, control, and timekeeping operations. This timekeeping is done by counting the number of pulses in a reference signal from an oscillation circuit not shown, for example. 
     The CPU  153  corrects the internal clock based on the time information calculated from the GPS time and time correction parameter, the current location (longitude and latitude) calculated from the GPS time and orbit information, and the time zone information stored in ROM  155  (storage unit). The CPU  153  also controls driving the drive mechanism  140  so that the internal time is displayed. As a result, the internal time is displayed on the electronic timepiece  10  by the hands  22 ,  23 ,  81  (see  FIG. 5 ). 
     Operation of the electronic timepiece  10  is described next.  FIG. 7  is a flow chart showing the flow of the operation setting the time zone on the electronic timepiece  10 . 
     First, in step S 1 , the CPU  153  drives the receiver unit  122  to receive satellite signals, acquire the GPS time and orbit information, and calculate the current location when the button  62  is operated or sunlight on the solar panel  135  is detected. 
     In step S 2 , the CPU  153  gets the time zone according to the current location. More specifically, the CPU  153  identifies the local time zone by comparing the location information with the time zone information described above, and sets (automatically sets) the time zone in the RAM  154 . 
     In step S 3 , the CPU  153  corrects the internal time according to the set time zone. More specifically, the CPU  153  calculates UTC from the GPS time and time correction parameter contained in the satellite signal, calculates the current local time (the standard time of the time zone) by adding the time difference used in the set time zone to the calculated UTC, and sets the calculated local time as the internal time. 
     In step S 4 , the CPU  153  controls the drive mechanism  140  ( FIG. 4 ) to display the current local time (internal time). 
     In step S 5 , the CPU  153  controls the drive mechanism  140  ( FIG. 4 ) when operation of the crown  50  is detected so that the second hand  21  ( FIG. 5 ) points to the time zone indicator  46  ( FIG. 5 ) corresponding to the time zone set in step S 2 . 
     In step S 6 , the user determines if correcting the time difference (time zone) indicated by the hand  21  is necessary, and the CPU  153  determines if an operation commanding adjusting the time zone was performed. If the adjustment operation is detected (step S 6  returns YES), control goes to step S 7 . If the adjustment operation is not detected (step S 6  returns NO), control goes to step S 9 . 
     In step S 7 , the CPU  153  detects operation of the crown  50 , drives the drive mechanism  140  ( FIG. 4 ) to move the hand  21  to the time zone indicator  46  ( FIG. 5 ) corresponding to the correct time zone selected by the user, and sets the correct time zone in RAM  154 . 
     Note that this operation is referred to as manually setting the time zone because the user operates the crown  50  to select the desired time zone indicator  46  ( FIG. 5 ). 
     In step S 8 , the CPU  153  corrects the internal time accordingly to the manually set time zone. 
     In step S 9 , the CPU  153  detects operation of the crown  50  and drives the drive mechanism  140  ( FIG. 4 ) to display the current local time. 
     Note that operation of the input device  157  (button  61 , button  62 , button  63 , button  64 , crown  50 ) described in this embodiment is simply one example, and the same operations may be performed using a different input device. 
     This embodiment of the invention describes an electronic timepiece  10  using power generated by the solar panel  135  and a storage battery  130  as a drive power source, but the invention is not so limited and a primary battery or other type of charging method may be used instead. The mechanisms inside the outside case  30  can be simplified by using a primary battery as the power source. Further alternatively, by using a storage battery that stores power produced by electromagnetic induction or other charging method, the electronic timepiece according to the invention can be used even where there is insufficient light for photovoltaic generation, or where battery replacement is difficult. 
     The electronic timepiece  10  according to the invention as described above has the following effect. 
     Forty different time differences, including the time difference in a geographical area (time zone) that uses a standard time of UTC+8.75, are set on a scale representing minutes and seconds, and corresponding time zone indicators  46  are set on the dial ring  40  and bezel  32 . 
     The electronic timepiece  10  also has functions for receiving satellite signals, and determining the time zone of the current location and displaying the current local time based on current location information and time information calculated from the received satellite signals. An electronic timepiece that can display the appropriate time in every time zone in the world (40 time zones) can therefore be provided. 
     The present invention is not limited to the foregoing embodiment, and can be varied in many ways by applying desirable changes or improvements to the foregoing embodiment. Some examples of such variations are described below. 
     Variations 
       FIG. 8  is a plan view showing an electronic timepiece according to a variation of the foregoing embodiment. 
     The electronic timepiece  10  according to the embodiment described above has a chronograph function as shown in  FIG. 5 , but the invention is not limited to such a configuration. 
     An electronic timepiece  200  according to a variation of the invention is described below. Note that like parts in this and the foregoing embodiment are identified by like reference numerals, and repetitive description thereof is omitted below. 
     As shown in  FIG. 8 , a scale dividing the perimeter into 60 divisions is formed around the outside of the dial  12 . The hands  22 ,  23 ,  24  display the internal time using this scale. 
     A rectangular calendar window  16  that is easy to read is disposed at 3:00 on the dial  12 . The calendar window  16  is an opening in the dial  12 , and a number can be seen through this opening. This number indicates the day value of the current date. 
     Markers indicating the 60 minute and second divisions are expressed on the dial  12 , and time zone indicators  46  for the 40 time zones used around the world are formed along the minute and second markers in the area around the outside edge of the dial  12 . The time zone of the internal time indicated by the hands  22 ,  23 ,  24  can be confirmed from the time zone indicator  46  pointed to by the hand  24  that jumps when the crown  50  is operated. 
     The electronic timepiece  200  according to this embodiment of the invention has the following effect in addition to the effects of the first embodiment described above. 
     This electronic timepiece  200  has a world time function corresponding to 40 different time zones. By omitting a chronograph function, the operability and readability of an electronic timepiece  200  that is compatible with every time zone in the world can be improved. 
     The invention being thus described, it will be obvious that it may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.