JP2013050336A - Electronic timepiece with built-in antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized electronic timepiece with a built-in antenna capable of maintaining the receiving performance of a GPS at a sufficiently high level while achieving miniaturization of an antenna.SOLUTION: An electronic timepiece with a built-in antenna includes: a cylindrical outer case 80 of which at least a part is formed of a nonconductive member; a time display part which displays time inside the outer case 80; an antenna body 40 which is housed in the outer case and has a shape formed by notching a part of a circular shape; and a pair of power feeding electrodes 40a and 40b which sandwich a recessed portion of the antenna body 40 and feed electric power to the antenna body 40. The antenna body 40 is disposed along the outer edge of a dial plate 11, and the power feeding electrodes 40a and 40b are disposed in a range of 06:00 to 10:00 of the time display part or in a range of 12:00 to 04:00 thereof.

Description

  The present invention relates to an electronic timepiece with a built-in antenna.

  Patent Document 1 discloses an antenna used for an electronic device or an electronic timepiece that is formed in a loop shape along the outer periphery of the lower surface of the timepiece glass. In addition, it is said that signal reception can be reliably performed while sufficiently securing the antenna length. In particular, Patent Document 1 also mentions that the feeding electrode of the loop antenna is arranged at the top of the dial, that is, at the 12 o'clock position.

  Further, Patent Document 2 discloses a structure in which a case of a receiver functions as a loop antenna with respect to a wrist-portable receiver. The loop antenna disclosed in Patent Document 2 has a shape that loops in the vertical or horizontal direction with respect to the arm. Specifically, the loop antenna is used with respect to the arm at the time of wearing using one side surface portion or both surface portions of the case. It has a shape that loops once or twice in the vertical or horizontal direction, connects two upper and lower semicircular antennas, and forms a feeding port at the other end.

JP-A-9-307329 Japanese Patent Laid-Open No. 9-247006

  By the way, since satellite signals in GPS (Global Positioning System) cannot be received indoors, they are received while wearing a wrist watch on the wrist and outdoors. At that time, the wearer is often in a posture where the arm on which the wristwatch is worn is lowered or the hand is placed in front of the body. In such an attitude, the normal direction of the watch surface is oriented in the horizontal direction, and in the loop antenna disclosed in the above-mentioned patent document, the direction in which the antenna gain is large does not coincide with the zenith direction, and the reception performance May not be fully utilized.

  The present invention has been made in view of the above-described circumstances. When receiving satellite signals in a GPS (Global Positioning System), the antenna orientation that is practically optimal based on ergonomics such as a posture that a wearer often takes outdoors. Therefore, it is an object of the present invention to provide an electronic timepiece with a built-in antenna that can maintain the reception performance sufficiently high while reducing the size of the antenna.

  In order to solve the above-described problems, an electronic timepiece with built-in antenna according to the present invention includes a cylindrical exterior case at least partially formed of a non-conductive member, and a time display for displaying the time inside the exterior case. An antenna body that is housed in the outer case and has a shape in which an annular part is cut out, and a pair of feeding electrodes that sandwich the cutout portion of the antenna body and feed power to the antenna body. , Arranged along the outer edge of the time display unit, and the pair of feeding electrodes are arranged in a range from 6 o'clock to 10 o'clock or from 12 o'clock to 4 o'clock in the time display unit. .

  In this electronic timepiece with built-in antenna, the antenna body functions as a loop antenna. More specifically, the antenna body is a so-called C-shaped loop antenna in which a part of an annular shape is cut out, and a pair of feeding electrodes serving as a start point and an end point of the loop antenna are located with a C-shaped cut-out portion interposed therebetween. It becomes. Therefore, by setting the peripheral length from the start point to the end point of the loop antenna to about one wavelength, it is possible to maintain the reception performance equivalent to the case where two half-wavelength dipole antennas are placed in parallel with the feeding electrode interposed therebetween. .

  In particular, in such a loop antenna, the radiation directivity is such that the direction in which the feed electrode is located is the maximum radiation direction when viewed from the center of the ring. By placing it within the range of time, the direction in which the antenna gain is large coincides with the direction of the zenith when the wearer is holding the wrist down or the hand is positioned in front of the body. Performance is fully demonstrated.

  As described above, according to the present invention, for example, when used for receiving satellite signals in GPS, it is possible to obtain a practically optimal antenna directivity based on ergonomics such as a posture that a wearer often takes outdoors. In addition, it is possible to provide an electronic timepiece with a built-in antenna capable of maintaining the reception performance sufficiently high while reducing the size of the antenna. At this time, the arrangement range of the feeding electrode has a certain width from the range from 6 o'clock to 10 o'clock or from 12 o'clock to 4 o'clock, for example, components such as crowns and operation buttons are arranged on the outer periphery of the outer case This is for avoiding interference between these components and the feeding electrode even when they are arranged on the surface.

  As the “non-conductive member”, materials other than metal, such as ceramics and plastics, can be used. Further, the “time display unit” includes a dial of a clock, and the time display on the dial includes a display by hands and a digital display such as liquid crystal. Examples of the pointer include an hour hand, a minute hand, and a second hand.

  Furthermore, the phrase “along the outer edge” includes a case where it is arranged in the plane of the time display unit and a case where it is arranged around. The “tubular shape” includes a rotating body represented by a cylinder. In addition, “annular” includes a circular shape or a substantially quadrangular shape, and includes an open ring shape (for example, C type) that is partially open, and a closed ring shape (for example, O type) that is entirely closed.

  In this electronic timepiece with built-in antenna, the antenna body may have a ring-shaped dielectric, and the metal portion of the antenna may be in contact with the dielectric. In this case, the antenna peripheral length can be shortened in combination with the wavelength shortening effect of the dielectric, and thus the entire antenna can be further downsized.

  In this case, “to be in contact with the dielectric” means that a ring-shaped dielectric is used as a base material, and a metal antenna electrode pattern is formed thereon by plating, silver paste printing, or the like. It includes integration by insert molding in which the antenna body is embedded in the dielectric.

  The antenna built-in type electronic timepiece preferably includes a metal back cover that closes an opening on the side opposite to the display direction of the time display unit among the two openings of the side surface. In this case, the radiation in the normal direction on the watch surface increases due to reflection by the metal back cover, and extremely high reception performance is obtained.

1 is an overall view of a GPS system including an antenna built-in electronic timepiece 100 (electronic timepiece 100) according to a first embodiment of the present invention. 2 is a plan view of the electronic timepiece 100. FIG. 2 is a partial cross-sectional view of the electronic timepiece 100. FIG. 2 is an exploded perspective view of a part of the electronic timepiece 100. FIG. 2 is a block diagram showing a circuit configuration of the electronic timepiece 100. FIG. 3 is a plan view showing positions of power supply electrodes in the electronic timepiece 100. FIG. FIG. 6 is an explanatory diagram showing a relationship between a mounting state of the electronic timepiece 100 and a position of a power feeding electrode. 4 is a perspective view showing a coordinate system related to a radiation pattern of an antenna body 40 of the electronic timepiece 100. FIG. FIG. 6 is a diagram showing a radiation pattern on the XY plane of the antenna body 40 of the electronic timepiece 100. 6 is a diagram showing a radiation pattern in the ZY plane of the antenna body 40 of the electronic timepiece 100. FIG. It is a partial cross section figure of the electronic timepiece 200 (electronic timepiece 200) with a built-in antenna which concerns on 2nd Embodiment of this invention.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. However, in each figure, the size and scale of each part are appropriately changed from the actual ones. Further, since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are attached thereto. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

[First Embodiment]
FIG. 1 is an overall view of a GPS system including an antenna built-in electronic timepiece 100 (hereinafter referred to as “electronic timepiece 100”) according to a first embodiment of the present invention. The electronic timepiece 100 is a wristwatch that receives radio waves (radio signals) from the GPS satellite 20 and corrects the internal time, and is a surface opposite to a surface (hereinafter referred to as “back surface”) that contacts the arm (hereinafter referred to as “surface”). ”).

  The GPS satellite 20 is a position information satellite that orbits a predetermined orbit over the earth, and transmits a navigation message superimposed on a 1.57542 GHz radio wave (L1 wave) to the ground. In the following description, the 1.57542 GHz radio wave on which the navigation message is superimposed is referred to as a “satellite signal”. The satellite signal is a right-handed circularly polarized wave.

  Currently, there are about 31 GPS satellites 20 (in FIG. 1, only 4 out of about 31 are shown), and in order to identify which GPS satellite 20 the satellite signal was transmitted from, The GPS satellite 20 superimposes a unique pattern of 1023 chips (1 ms period) called a C / A code (Coarse / Acquisition Code) on the satellite signal. The C / A code looks like a random pattern with each chip being either +1 or -1. Therefore, by correlating the satellite signal and the pattern of each C / A code, the C / A code superimposed on the satellite signal can be detected.

  The GPS satellite 20 is equipped with an atomic clock, and the satellite signal includes extremely accurate time information (hereinafter referred to as “GPS time information”) measured by the atomic clock. Further, a slight time error of the atomic clock mounted on each GPS satellite 20 is measured by a control segment on the ground, and the satellite signal includes a time correction parameter for correcting the time error. The electronic timepiece 100 receives a satellite signal transmitted from one GPS satellite 20, and corrects the internal time to an accurate time by using GPS time information and a time correction parameter included therein.

  The satellite signal includes orbit information indicating the position of the GPS satellite 20 on the orbit. The electronic timepiece 100 can perform positioning calculation using GPS time information and orbit information. The positioning calculation is performed on the assumption that the internal time of the electronic timepiece 100 includes some error. That is, in addition to the x, y, and z parameters for specifying the three-dimensional position of the electronic timepiece 100, the time error is also an unknown number. Therefore, the electronic timepiece 100 generally receives satellite signals respectively transmitted from four or more GPS satellites, and performs positioning calculation using GPS time information and orbit information included therein.

  FIG. 2 is a plan view of the electronic timepiece 100. As shown in FIG. 2, the electronic timepiece 100 includes a cylindrical outer case 80 formed of a nonconductive member such as ceramic or plastic. An annular bezel 81 formed of a non-conductive member such as the like is fitted. A disc-shaped dial plate 11 is arranged as a time display portion on the inner peripheral side of the bezel 81 via an annular dial ring 83 made of plastic. On the dial plate 11, the time and date are displayed. A pointer 13 (13a to 13c) for displaying and a liquid crystal display panel 14 are arranged. The opening on the surface side of the outer case 80 is closed with a cover glass 84 through a bezel 81, and the dial plate 11, the hands 13 (13 a to 13 c) and the liquid crystal display panel are connected through the cover glass 84. 14 is visible. In FIG. 2, the characters “TYO” displayed on the liquid crystal display panel 14 mean “Tokyo” and display the time of Japan in the world time function.

  The dial ring 83 has a horizontal annular portion in contact with the inner peripheral surface of the bezel 81 on the outer peripheral side, and a mortar-shaped portion whose inner peripheral side is inclined inward. A doughnut-shaped storage space 82 is defined by the mortar-shaped portion and the inner peripheral surface of the bezel 81. In this storage space 82, a so-called C-shaped antenna body 40 with a part of the annular shape cut out is stored.

  The antenna body 40 is configured by arranging a loop antenna with a ring portion cut out in a ring shape along the outer edge of the dial plate 11 which is a time display unit. In the present embodiment, the antenna body 40 is arranged around the dial plate 11. The two feeding electrodes 40 a and 40 b for the antenna body 40 are arranged at the 6 o'clock to 9 o'clock position or the 12 o'clock to 3 o'clock position on the dial plate 11. The feeding electrodes 40 a and 40 b are electrodes that are located at the start point and the end point of the antenna body 40 and feed the antenna body 40.

  Further, the electronic timepiece 100 manually receives the satellite signal from at least one GPS satellite 20 and corrects the internal time information by manually operating the crown 16 and the operation buttons 17 and 18 shown in FIGS. A mode (time information acquisition mode) and a mode (position information acquisition mode) in which satellite signals from a plurality of GPS satellites 20 are received and positioning calculation is performed to correct the time difference of internal time information are configured. The electronic timepiece 100 can also execute the time information acquisition mode and the position information acquisition mode periodically (automatically).

  FIG. 3 is a partial cross-sectional view showing the internal structure of the electronic timepiece 100, and FIG. 4 is an exploded perspective view of a part of the electronic timepiece 100. As shown in FIGS. 3 and 4, in the electronic timepiece 100, an annular bezel 81 made of ceramic is fitted on the surface side of a cylindrical outer case 80 made of ceramic, and the bezel 81 A ring-shaped dial ring 83 made of plastic is attached along the inner periphery. Of the two openings of the exterior case 80, the opening on the front side is closed with a cover glass 84 via an annular bezel 81, and the opening on the back side is closed with a back cover 85 formed of metal. ing. The metal back cover 85 and the metal outer case 80 are fixed by screw grooves.

  The electronic timepiece 100 also includes a secondary battery 27 such as a lithium ion battery inside the outer case 80. The secondary battery 27 is charged with electric power generated by a solar panel 87 described later. That is, solar charging is performed. The electronic timepiece 100 includes a light-transmitting dial plate 11, a pointer shaft 12 penetrating the dial plate 11, and a plurality of hands 13 (circling around the pointer shaft 12 to indicate the current time. A second hand 13a, a minute hand 13b and an hour hand 13c), and a driving mechanism 30 for driving the plurality of hands 13 by rotating the pointer shaft 12. The pointer shaft 12 extends in the front and back direction along the central axis of the exterior case 80.

  The dial plate 11 is a circular plate member that constitutes a time display unit that displays the time inside the outer case 80, is formed of a light-transmitting material such as plastic, and has a pointer 13 (13a) between it and the cover glass 84. ˜c) are arranged inside the dial ring 83. A hole through which the pointer shaft 12 passes is formed at the center of the dial 11 and an opening for allowing the liquid crystal display panel 14 to be visually recognized is formed.

  The drive mechanism 30 is attached to the main plate 38 and includes a step motor and a gear train such as a gear. The step motor rotates the hands 13 through the wheel train to drive the plurality of hands 13. Specifically, the hour hand 13c makes a full turn in 12 hours, the minute hand 13b in 60 minutes, and the second hand 13a in 60 seconds. Further, the base plate 38 to which the drive mechanism 30 is attached is disposed so as to sandwich the dial plate 11 between the hands 13.

  The electronic timepiece 100 also includes a solar panel 87 that performs photovoltaic power generation inside the exterior case 80. The solar panel 87 is a circular flat plate in which a plurality of solar cells (photovoltaic elements) that convert light energy into electric energy (electric power) are connected in series. The solar panel 87 is disposed between the dial 11 and the drive mechanism 30 and has pointers. It extends along the cross section of the shaft 12. The solar panel 87 is disposed inside the dial ring 83 in the extending direction. In addition, a hole through which the pointer shaft 12 passes is formed at the center of the solar panel 87, and an opening for allowing the liquid crystal display panel 14 to be visually recognized is formed.

  The electronic timepiece 100 includes an antenna connection pins 44A and 44B, a circuit board 25, a balun 10 mounted on the circuit board 25, a GPS receiving unit (wireless receiving unit) 26, and a control unit 70 inside the exterior case 80. Is provided. The balun 10 is a balanced-unbalanced conversion element, and converts a balanced signal from the antenna body 40 that operates by balanced feeding into an unbalanced signal that can be handled by the GPS receiver 26.

The electronic timepiece 100 includes an antenna body 40 having a shape in which an annular part is cut out. The antenna body 40 is formed by using a ring-shaped dielectric 40d as a base material and forming a metal antenna pattern 40c thereon by plating or silver paste printing. In the present embodiment, the antenna body 40 is disposed around the dial plate 11 and is accommodated on the inner peripheral surface side of the bezel 81, and the upper portion thereof is covered with a dial ring 83 and a cover glass 84. As this dielectric, a dielectric material that can be used at high frequencies, such as titanium oxide, can be formed by mixing it with a resin, and this makes it possible to further reduce the size of the antenna in combination with shortening the wavelength of the dielectric.
For example, in the case of GPS reception, since it is 1.575 GHz, one wavelength is 19 cm. In order to embed a normal antenna in a bezel portion of a wristwatch, it does not fit as it is, and the wavelength needs to be shortened. In the present embodiment, since the wavelength shortening by the dielectric becomes √εr, in the present embodiment, εr = about 5 to 10 is used as the dielectric 40d. Thereby, even if it is an antenna for GPS reception, a 1 wavelength loop antenna can be accommodated in a wristwatch, and size reduction of an antenna can be achieved.

  The antenna body 40 is fed with power through two feeding electrodes 40a and 40b positioned at both ends of the antenna body 40, that is, at the C-shaped cutout portion. The feeding electrodes 40a and 40b are antenna connection pins arranged on the lower surface of the antenna. 44A and 44B are connected. The antenna connection pins 44A and 44B are pin-shaped connectors made of metal with a built-in spring. The antenna connection pins 44A and 44B protrude from the circuit board 25 and pass through the insertion holes 38a and 38b opened in the ground plane 38, so that a storage space is provided. The circuit board 25 and the antenna body 40 in the storage space 82 are connected to each other.

  In the present embodiment, power supply to the antenna body 40 is balanced power supply from the balun 10 through the two power supply electrodes 40a and 40b. Specifically, positive and negative power supply electrodes 40a and 40b are provided at both ends of the antenna body 40, and these two power supply electrodes 40a and 40b are connected to the antenna connection pins 44A and 44B. Balanced power feeding is performed via these antenna connection pins 44 </ b> A and 44 </ b> B, and the GPS receiver 26 receives a radio signal using the antenna body 40. Note that since the antenna body 40 is a one-wavelength loop antenna, it has a self-balancing action with respect to power feeding, and can be fed directly without the balun 10.

  FIG. 5 is a block diagram showing a circuit configuration of the electronic timepiece 100. As shown in FIG. 5, the electronic timepiece 100 includes a GPS receiving unit 26 and a control display unit 36. The GPS receiver 26 performs processing such as satellite signal reception, GPS satellite 20 acquisition, position information generation, and time correction information generation. The control display unit 36 performs processing such as holding internal time information and correcting internal time information.

  The solar panel 87 charges the secondary battery 27 through the charge control circuit 29. The electronic timepiece 100 includes regulators 34 and 35, and the secondary battery 27 supplies drive power to the control display unit 36 via the regulator 34 and to the GPS reception unit 26 via the regulator 35. The electronic timepiece 100 also includes a voltage detection circuit 37 that detects the voltage of the secondary battery 27. Instead of the regulator 35, for example, a regulator 35-1 that supplies driving power to the RF unit 50 (details will be described later) and a regulator 35-2 that supplies driving power to the baseband unit 60 (details will be described later). Both of them may be provided separately. The regulator 35-1 may be provided inside the RF unit 50.

  The electronic timepiece 100 includes an antenna body 40, a balun 10, and a SAW (Surface Acoustic Wave) filter 32. As described in FIG. 1, the antenna body 40 receives satellite signals from the plurality of GPS satellites 20. However, since the antenna body 40 also receives some unnecessary radio waves other than the satellite signal, the SAW filter 32 performs a process of extracting the satellite signal from the signal received by the antenna body 40. That is, the SAW filter 32 is configured as a band-pass filter that passes a 1.5 GHz band signal.

  The GPS receiving unit 26 includes an RF (Radio Frequency) unit 50 and a baseband unit 60. As will be described below, the GPS receiver 26 performs a process of acquiring satellite information such as orbit information and GPS time information included in the navigation message from the 1.5 GHz band satellite signal extracted by the SAW filter 32.

  The RF unit 50 includes an LNA (Low Noise Amplifier) 51, a mixer 52, a VCO (Voltage Controlled Oscillator) 53, a PLL (Phase Locked Loop) circuit 54, an IF amplifier 55, an IF (Intermediate Frequency) filter 56, an ADC (ADC). (A / D converter) 57 and the like.

  The satellite signal extracted by the SAW filter 32 is amplified by the LNA 51. The satellite signal amplified by the LNA 51 is mixed with the clock signal output from the VCO 53 by the mixer 52 and down-converted to an intermediate frequency band signal. The PLL circuit 54 compares the phase of the clock signal obtained by dividing the output clock signal of the VCO 53 with the reference clock signal, and synchronizes the output clock signal of the VCO 53 with the reference clock signal. As a result, the VCO 53 can output a clock signal with a stable frequency accuracy of the reference clock signal. For example, several MHz can be selected as the intermediate frequency.

  The signal mixed by the mixer 52 is amplified by the IF amplifier 55. Here, by the mixing in the mixer 52, a high-frequency signal of several GHz is generated together with the signal in the intermediate frequency band. Therefore, the IF amplifier 55 amplifies a high frequency signal of several GHz along with the signal in the intermediate frequency band. The IF filter 56 passes the signal in the intermediate frequency band and removes the high frequency signal of several GHz (precisely, attenuates below a predetermined level). The intermediate frequency band signal that has passed through the IF filter 56 is converted into a digital signal by an ADC (A / D converter) 57.

  The baseband unit 60 includes a DSP (Digital Signal Processor) 61, a CPU (Central Processing Unit) 62, an SRAM (Static Random Access Memory) 63, and an RTC (Real Time Clock) 64. The baseband unit 60 is connected to a crystal oscillation circuit with temperature compensation circuit (TCXO: Temperature Compensated Crystal Oscillator) 65, a flash memory 66, and the like.

  A crystal oscillation circuit (TCXO) 65 with a temperature compensation circuit generates a reference clock signal having a substantially constant frequency regardless of the temperature. The flash memory 66 stores, for example, time difference information. The time difference information is information in which time difference data (such as a correction amount for UTC associated with coordinate values (for example, latitude and longitude)) is defined.

  When set to the time information acquisition mode or the position information acquisition mode, the baseband unit 60 performs a process of demodulating the baseband signal from the digital signal (intermediate frequency band signal) converted by the ADC 57 of the RF unit 50.

  In addition, when the time information acquisition mode or the position information acquisition mode is set, the baseband unit 60 generates a local code having the same pattern as each C / A code in the satellite search process described later, and generates a baseband signal. A process of correlating each C / A code included and the local code is performed. Then, the baseband unit 60 adjusts the local code generation timing so that the correlation value for each local code has a peak, and if the correlation value is equal to or greater than the threshold, it synchronizes with the GPS satellite 20 of that local code (that is, The GPS satellite 20 is captured). Here, the GPS system employs a CDMA (Code Division Multiple Access) method in which all GPS satellites 20 transmit satellite signals of the same frequency using different C / A codes. Therefore, by detecting the C / A code included in the received satellite signal, it is possible to search for a GPS satellite 20 that can be captured.

Further, the baseband unit 60 uses a local code having the same pattern as the C / A code of the GPS satellite 20 in order to acquire the satellite information of the captured GPS satellite 20 in the time information acquisition mode or the position information acquisition mode. Performs processing to mix baseband signals. In the mixed signal, a navigation message including satellite information of the captured GPS satellite 20 is demodulated. Then, the baseband unit 60 detects TLM words (preamble data) of each subframe of the navigation message, and acquires satellite information such as orbit information and GPS time information included in each subframe (for example, stored in the SRAM 63). ) Process. Here, the GPS time information is the week number data (WN) and the Z count data, but may be only the Z count data when the week number data has been acquired previously.
And the baseband part 60 produces | generates the time correction information required in order to correct internal time information based on satellite information.

  In the time information acquisition mode, more specifically, the baseband unit 60 performs time measurement calculation based on the GPS time information, and generates time correction information. The time correction information in the time information acquisition mode may be, for example, GPS time information itself or information on a time difference between the GPS time information and the internal time information.

On the other hand, in the position information acquisition mode, more specifically, the baseband unit 60 performs positioning calculation based on GPS time information and orbit information, and the position information (more specifically, the electronic timepiece 100 is Get the latitude and longitude of the location. Further, the baseband unit 60 refers to the time difference information stored in the flash memory 66 and acquires time difference data associated with the coordinate values (for example, latitude and longitude) of the electronic timepiece 100 specified by the position information. . In this way, the baseband unit 60 generates satellite time data (GPS time information) and time difference data as time correction information. As described above, the time correction information in the position information acquisition mode may be the GPS time information and the time difference data itself. For example, instead of the GPS time information, the time correction information is a time difference data between the internal time information and the GPS time information. Also good.
The baseband unit 60 may generate time correction information from the satellite information of one GPS satellite 20, or may generate time correction information from the satellite information of a plurality of GPS satellites 20.

  The operation of the baseband unit 60 is synchronized with the reference clock signal output from the crystal oscillation circuit with temperature compensation circuit (TCXO) 65. The RTC 64 generates timing for processing satellite signals. The RTC 64 is counted up by the reference clock signal output from the TCXO 65. The RTC 64 provided in the baseband unit 60 operates only during reception of the satellite information of the GPS satellite 20, and holds GPS time information.

The control display unit 36 includes a control unit 70, a drive circuit 74, and a crystal resonator 73.
The control unit 70 includes a storage unit 71 and an RTC (Real Time Clock) 72 and performs various controls. The control unit 70 can be configured by a CPU, for example.
The controller 70 sends a control signal to the GPS receiver 26 and controls the reception operation of the GPS receiver 26. Further, the control unit 70 controls the operation of the regulator 34 and the regulator 35 based on the detection result of the voltage detection circuit 37. The control unit 70 controls the driving of all the hands via the drive circuit 74.

  The storage unit 71 stores internal time information. The RTC 72 operates constantly, measures the internal time for time display, and generates internal time information. The internal time information is time information measured inside the electronic timepiece 100 and is updated by a reference clock signal generated by the crystal unit 73. Therefore, even if the power supply to the GPS receiver 26 is stopped, the internal time information can be updated and the hand movement of the pointer can be continued.

  When the time information acquisition mode is set, the control unit 70 controls the operation of the GPS receiving unit 26, corrects the internal time information based on the GPS time information, and stores the internal time information in the storage unit 71. More specifically, the internal time information is corrected to UTC (Coordinated Universal Time) obtained by adding a UTC offset to the acquired GPS time information. Further, when the position information acquisition mode is set, the control unit 70 controls the operation of the GPS receiving unit 26, corrects and stores the internal time information based on the satellite time data (GPS time information) and the time difference data. Store in the unit 71.

  As described above, in the electronic timepiece 100, the antenna body 40 is a C-shaped loop antenna as a whole, and the pair of feeding electrodes 40a and 40b that are the start and end points of the loop antenna sandwich the C-shaped notch portion. Will be located at. For this reason, by setting the peripheral length from both ends of the antenna body 40, that is, the start point to the end point of the loop antenna, to about one wavelength shortened by the dielectric 40d, two half-wavelength dipole antennas are connected to the feed electrode 40a and It is possible to maintain the reception performance equivalent to the case of placing them in parallel across 40b.

  In particular, in the electronic timepiece 100 according to the present embodiment, the radiation directivity is such that the direction in which the power supply electrodes 40a and 40b are seen from the center of the ring is the maximum radiation direction. By placing it in the 10 o'clock range or the 12 o'clock to 4 o'clock range, the direction in which the antenna gain is large when the wearer is in the posture of lowering the wrist arm or placing his hand in front of the body This coincides with the zenith direction, and reception performance is sufficiently exhibited.

  In detail, since satellite signals cannot be received indoors, reception is performed while wearing a wrist watch on the arm and outdoors, in which case the wearer is holding his arm down or holding his hand in front of the body. In many cases, the posture is positioned in the position. Therefore, as shown in FIGS. 6 and 7, the probability that the 6 o'clock to 10 o'clock position of the electronic timepiece 100 faces the zenith direction is high. In the electronic timepiece 100 according to the present embodiment, the antenna feeding position is from 6 o'clock to 10 o'clock, or from 12 o'clock to 4 o'clock where the same performance can be obtained. The probability that the larger direction is toward the zenith direction is higher.

  8-10 is explanatory drawing of the radiation pattern of the antenna body 40. FIG. FIG. 8 is an explanatory diagram showing a coordinate system centered on the antenna body 40. The center point of the circular antenna body 40 (radius a) is the origin, the horizontal plane including the watch surface is the XY plane, and the watch surface is shown. The normal line direction is taken as the Z axis, and the feeding electrodes 40a and 40b are installed on the X axis. The radiation pattern shown in FIG. 9 is a radiation pattern on the Y-X plane in which θ shown in FIG. 8 is set to 90 °, and the feeding electrodes 40a and 40b are positioned on the X axis near the origin. The radiation pattern shown in FIG. 10 is a radiation pattern in the ZX plane in which φ shown in FIG. 8 is set to 90 °, and the feeding electrodes 40a and 40b are located on the origin. In FIG. 10, the solid line is a radiation pattern with a back cover, and the wavy line is a radiation pattern with no back cover.

  As shown in FIG. 9, when feeding electrodes 40a and 40b are positioned on the X axis, the X axis direction is the maximum radiation direction and the antenna gain is maximum, the Y axis direction is the null value, and the antenna gain is low. It has become. Therefore, when the power supply electrodes 40a and 40b are positioned in the range of 6 o'clock to 10 o'clock or 12 o'clock to 4 o'clock as in the present invention, the wristwatch is worn on the wrist and reception is performed outdoors. The radiation directivity of the antenna body 40 can be maximized in a posture that a wearer takes many ergonomically.

  In FIG. 10, the antenna radiation patterns are compared with and without the metal back cover. It can be seen that if there is a metal back on the YZ plane, radiation in the dial direction (Z-axis) increases due to reflection, and desirable antenna characteristics can be obtained when the watch surface is directed to the apex. If the case is made of metal and is too close to the antenna, the antenna characteristics deteriorate, but in this embodiment, the outer case 80 is a non-conductive member, so there is no such influence. The back cover 85 is separated by the ground plane 38, the drive mechanism 30, and the like, and has an appropriate distance from the antenna body 40. Therefore, the back cover 85 can function effectively as a reflector without deteriorating antenna characteristics.

  In the electronic timepiece 100, the antenna can be reduced in size by utilizing the wavelength shortening by the dielectric 40d. That is, since the wavelength shortening due to the dielectric becomes √εr, in this embodiment, the dielectric 40d is about εr = 5 to 10, so that even a GPS receiving antenna can be used in a wristwatch. A one-wavelength loop antenna can be accommodated, and the antenna can be miniaturized. Further, since a ground plate is not required, there is an advantage that it is easy to use even in a small device that does not require a large size ground plate. In the present embodiment, the antenna body 40 has the antenna pattern 40c formed on the surface of the ring-shaped dielectric 40d by plating, silver paste printing, or the like. When the antenna pattern 40c is formed on the surface, it is easy to process and the frequency adjustment is also easy.

  Furthermore, since the antenna body 40 is balancedly fed through the feeding electrodes 40a and 40b, the feeding electrodes 40a and 40b can form a balanced antenna pattern, and reception performance can be improved. Moreover, since the metal back cover that closes the opening on the opposite side to the display direction of the time display part among the two openings of the side surface part is provided, the normal direction on the watch surface is reflected by the reflection from the metal back cover. Radiation becomes larger, and extremely high reception performance can be obtained.

  As described above, according to the present invention, when receiving a satellite signal by GPS, it is possible to obtain a practically optimal antenna directivity based on ergonomics such as the posture of a wearer outdoors, and to reduce the size of the antenna. The reception performance can be maintained sufficiently high.

[Second Embodiment]
FIG. 11 is a partial cross-sectional view of an antenna built-in electronic timepiece 200 (electronic timepiece 200) according to the second embodiment of the present invention. The electronic timepiece 200 is different from the electronic timepiece 100 in that an antenna body 41 is provided instead of the antenna body 40. The antenna body 41 has an annular dielectric body 41d and is different from the antenna body 40 in that the antenna pattern 41c is configured to contact the dielectric body 41d.

  Specifically, as shown in FIG. 11, in this embodiment, in the storage space 82 defined in a donut shape by the dial ring 83 and the inner peripheral surface of the bezel 81, it extends in the circumferential direction. The antenna body 41 is formed by embedding a metal antenna pattern 41c in the dielectric body 41d. The cross-sectional shape of the dielectric 41d is substantially square.

  The dielectric 41d is a dielectric such as a dielectric ceramic, but may be formed by insert molding using plastic mixed with a dielectric. In the present embodiment, the feeding electrodes 41a and 41b are located at one point on the circumference of the doughnut-shaped dielectric 41d, and the antenna pattern 41c inside the dielectric 41d is cut out of an annular portion. It has a so-called C shape. The dielectric 41d and the antenna pattern 41c are covered with a dial ring 83 as viewed from the front side.

  In the second embodiment, the outer case 80 is made of metal, and the outer case 80 and the metal back cover 85 are made to function as a ground plate. That is, one feeding electrode 41a or 41b of the antenna body 41 is connected to the metal outer case 80 via the conduction spring 38c. The other feeding electrode 41a or 41b is fed through the antenna connection pin 44. At this time, since the antenna body 41 is a one-wavelength loop antenna, it has a self-balancing action with respect to power feeding, and can be fed directly without going through the balun 10.

  As is clear from the above description, according to the electronic timepiece 200, the same effect as the electronic timepiece 100 can be obtained. As a further effect, the antenna perimeter can be shortened in combination with the wavelength shortening effect of the dielectric material 41d, whereby the entire antenna can be further downsized. Further, by contacting the dielectric 41d, the metal antenna pattern 41c can be fixed so as not to move, and the stability of the apparatus can be improved. Further, by making the cross section of the antenna body 41 substantially square, there is no wasted space, the space in the watch can be used effectively, and it can contribute to downsizing.

  In the present embodiment, since the outer case 80 functions as a ground plate through the conduction spring 38c through the feeding electrode 41a or 41b on the loop antenna side, the antenna connecting pin 44 can be made into one piece. Thus, the cost can be reduced, and the degree of freedom of the position where the feeding electrode is arranged can be increased. Furthermore, the size reduction can be promoted by omitting the balun 10 due to the self-balancing action with respect to the power supply of the antenna body 41.

DESCRIPTION OF SYMBOLS 100,200 ... Electronic clock with built-in antenna, 40, 41 ... Antenna body, 40a, 40b, 41a, 41b ... Feed electrode, 41c ... Antenna pattern, 41d ... Dielectric, 44A, 44B ... Antenna connection pin, 11 ... Dial , 12 ... Pointer shaft, 13 (13a, 13b, 13c) ... Pointer, 26 ... GPS receiver, 30 ... Drive mechanism, 80 ... Exterior case, 81 ... Bezel, 82 ... Storage space, 84 ... Cover glass, 85 ... Back Lid, 87… Solar panel.

Claims (5)

A cylindrical outer case at least partially formed of a non-conductive member;
A time display unit for displaying the time inside the outer case;
The antenna body housed in the outer case and having a shape in which a part of the annular shape is cut out,
A pair of feeding electrodes for feeding the antenna body with the notch portion of the antenna body sandwiched therebetween,
The antenna body is disposed along an outer edge of the time display unit,
The pair of power supply electrodes are arranged in a range from 6 o'clock to 10 o'clock or from 12 o'clock to 4 o'clock in the time display unit
An electronic timepiece with a built-in antenna.   The electronic timepiece with built-in antenna according to claim 1, wherein the antenna body is arranged around the time display unit.   3. The antenna built-in type electronic timepiece according to claim 1, wherein the antenna body receives radio waves from a position information satellite.   The antenna built-in type according to any one of claims 1 to 3, wherein the antenna body includes an annular dielectric body, and the antenna body is configured to be in contact with the dielectric body. Electronic clock. 5. The antenna built-in electronic timepiece includes a metal back cover that closes an opening opposite to a display direction of the time display unit among two openings of the side surface part. The antenna built-in type electronic timepiece of any one of them.

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