JP2013050349A - Electronic timepiece with built-in antenna - Google Patents

Abstract

A small-sized electronic timepiece with a built-in antenna capable of maintaining a sufficiently high GPS reception performance while reducing the size of the antenna.
SOLUTION: A cylindrical outer case 80 at least partially formed of a non-conductive member, a circuit board 25 in which a GPS receiving unit 26 that is housed in the outer case 80 and performs wireless communication is disposed, and an outer case An antenna body 40 housed in a case 80 and connected to the circuit board 25. The circuit board 25 and the antenna body 40 are arranged in the same plane substantially parallel to the circuit board 25, and the antenna body The center position of 40 is arranged in the range from 6 o'clock to 10 o'clock or 12 o'clock to 4 o'clock on the dial 11.
[Selection] Figure 3

Description

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

  Patent Document 1 discloses a chip antenna that is unbalanced and fed with respect to an arm-mounted electronic device with a wireless function. In this Patent Document 1, the chip antenna disposed on the substrate is disposed in the vicinity of the IC for wireless communication, and the chip antenna is disposed on the plane substantially parallel to the circuit board as a projection plane. The projection and the orthographic projection of the wireless communication IC are arranged so as not to overlap.

  Patent Document 2 discloses a solar cell that performs photovoltaic power generation and a GPS antenna that receives a satellite signal from a GPS satellite, with regard to an electronic timepiece. In Patent Document 2, at least a part of a receiving surface of a GPS antenna disposed on an antenna substrate connected to a circuit board via a connector is at least one of the back surfaces of a dial plate disposed on the upper portion of the GPS antenna. The solar cell is not arranged in a space sandwiched between the back surface of the dial and the receiving surface of the GPS antenna.

JP 2003-152582 A JP 2010-96707 A

  By the way, for example, since a satellite signal in GPS (Global Positioning System) cannot be received indoors, it is received while wearing a wrist watch on the wrist and being 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. With the chip 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. A circuit board on which a wireless communication circuit that performs wireless communication is disposed, and an antenna body that is housed in the exterior case and connected to the circuit board and is unbalanced and fed from the wireless communication circuit. And the center position of the antenna body is arranged in the range from 6 o'clock to 10 o'clock or from 12 o'clock to 4 o'clock in the time display section.

  In this antenna built-in type electronic timepiece, a pair of an antenna body and a circuit board functions as one antenna as a whole. As this antenna body, a helical antenna, an inverted F antenna, a chip antenna or a patch antenna obtained by chipping or patching an inverted L antenna can be used. Specifically, as the chip antenna, a helical antenna winding structure portion, an inverted F-type antenna, or an inverted L-type antenna, which is patterned on a ceramic dielectric for wavelength reduction, can be used. As the antenna, an element formed by etching an element of a reverse F-type antenna or a reverse L-type antenna on a metal pasted on an insulating substrate can be used.

  In such an antenna body and circuit board, the radiation directivity is such that the direction of the center position of the antenna body is the maximum radiation direction when viewed from the connection point between the antenna body and the circuit board. By placing it in the 6 o'clock to 10 o'clock range or the 12 o'clock to 4 o'clock range, the antenna gain can be reduced when the wearer is in the position of lowering his wrist or placing his hand in front of his body. The large direction coincides with the zenith direction, and the reception performance is sufficiently exhibited.

  From the above, according to the present invention, for example, when receiving satellite signals in GPS, it is possible to obtain a practically optimal antenna directivity based on ergonomics such as the posture that a wearer often takes outdoors, and to improve reception performance. An electronic timepiece with a built-in antenna that can be kept sufficiently high can be provided. At this time, the arrangement range of the center position of the antenna body 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, parts such as crowns and operation buttons are external This is for avoiding interference between these components and the antenna body even when it is arranged on the outer peripheral surface of the case.

  As the “non-conductive member”, materials other than metal, for example, ceramic or plastic can be used, and “cylinder” includes a rotating body represented by a cylinder or a square tube. Further, the antenna body and the circuit board may be arranged in the same plane substantially parallel to the circuit board. This means that the joint surface between the antenna body and the circuit board or the center position of the antenna body is arranged in a plane including the plate-like circuit board, and the antenna body is mounted directly on the circuit board. In addition to the above-described form, a form mounted on a substrate different from the circuit board is also included.

  In the above invention, the electronic timepiece with a built-in antenna has one of the two openings of the exterior case closed with a cover glass and the other opening closed with a back cover, and the antenna body is the cover of the circuit board. It is preferable that the wireless communication circuit is disposed on the glass side, and the wireless communication circuit is disposed on the back cover side. In this case, a circuit board can be interposed between the radio communication circuit such as a GPS module and the antenna body, and in-band (in-band of received signal) noise such as a clock signal generated from the radio communication circuit is generated in the antenna body. Adverse effects on the environment can be reduced. This can reduce the deterioration of the sensitivity of the antenna body.

  In the above invention, the electrical length of the antenna body and the circuit board is preferably ¼ wavelength of the received radio wave. In this case, the circuit board functions as a ground plate of the antenna body by setting the substantial element length of the antenna body and the circuit board to, for example, a quarter wavelength of the radio wave to be received such as a GPS satellite signal. In addition, it is possible to maintain appropriate reception performance for radio waves to be received. The “electric length” is a substantial electrical antenna length with respect to the wavelength of the received radio wave, and is determined from the physical element length of the antenna body and the dielectric constant of each element. Since chip antennas and patch antennas have dielectric bodies, the use of these as antenna bodies can reduce the size by shortening the wavelength. In addition, since the circuit board also includes a dielectric, it is only necessary to provide a wiring pattern whose size is shortened by the dielectric constant of the circuit board, thereby reducing the size.

  In the above invention, the electronic timepiece with built-in antenna further includes a solar panel for photovoltaic power generation, and the solar panel preferably has a cutout portion overlapping the antenna body in plan view as viewed from the display direction of the time display unit. . In this case, electric power can be obtained by photovoltaic power generation of the solar panel. At this time, the reception performance can be prevented from deteriorating due to the influence of the metal part such as the electrode of the solar panel by cutting out the part where the solar panel and the antenna body overlap in plane with respect to the received radio wave. . In addition, parts made of materials other than metal, such as a calendar display part, can be used in this notch for effective use, ensuring the maximum solar panel area while maintaining reception performance. Thus, it is possible to avoid a decrease in the amount of power generation.

In the above invention, the back cover is preferably made of metal. 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.
In the above invention, the antenna body is preferably a chip antenna or a patch antenna.

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 the position of a feeding point 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 feeding point. 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 top view of the electronic timepiece 200 which concerns on 2nd Embodiment of this invention. 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 that contacts 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 ground plane 38 is disposed below the dial ring 83, and an antenna body 40 formed in a rectangular cross section is accommodated on the lower surface side of the ground plane 38.

  The antenna body 40 is a chip antenna that is disposed around the drive mechanism 30 housed in the ground plane 38 and has electrodes formed on the dielectric surface. In this embodiment, the center position of the antenna body 40 is the dial plate. 11 at 6 o'clock to 10 o'clock position or 12 o'clock to 4 o'clock position. A recess 38a having a shape matching the planar shape of the antenna body 40 is formed on the lower surface of the ground plane 38, and the antenna body 40 is accommodated in the recess 38a.

  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. An annular 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 by photovoltaic power generation 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 plate 11, and an opening 11 a for visually recognizing the liquid crystal display panel 14 is formed.

  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 87a 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.

  Further, the electronic timepiece 100 includes a circuit board 25 inside the outer case 80, and the circuit board 25 includes a GPS receiving unit (wireless communication circuit) 26 and a control unit 70 disposed on the back cover 85 side. The GPS receiver 26 receives a signal from the antenna body 40 and performs wireless communication.

  The electronic timepiece 100 includes an antenna body 40 having a rectangular cross section connected to the circuit board 25. The antenna body 40 is a chip antenna, for example, a helical antenna having a winding structure, or an inverted F antenna patterned on a ceramic dielectric for wavelength reduction. In the present embodiment, the antenna body 40 is mounted on the cover glass 84 side on the circuit board 25 and is disposed in the same plane substantially parallel to the circuit board 25 and is combined with the circuit board 25 functioning as a ground plate. Therefore, it functions as an antenna as a whole. 6A and 6B, the center position of the antenna body 40 indicates the center of the three-dimensional shape, and the center position of the antenna body 40 or the connection between the antenna body 40 and the circuit board 25. As long as the surface is disposed in a plane including the plate-like circuit board 25, the antenna body 40 is mounted directly on the circuit board 25 and mounted on a board different from the circuit board 25. Alternatively, the antenna body 40 may be mounted across the circuit board 25 and another board.

Here, the electrical length of the antenna body 40 is a quarter wavelength of the satellite signal, and the circuit board 25 also includes a dielectric material to serve as a ground plate, and the electrical length is the satellite signal. 1/4 wavelength. The “electric length” is a substantial electrical antenna length with respect to the wavelength of the satellite signal, and is determined from the physical element length of the antenna body and the dielectric constant of each element. In addition, as the dielectric, a dielectric material that can be used at high frequencies, such as titanium oxide, can be mixed with the resin, and the antenna body 40 and the circuit board 25 can be downsized together with the shortening of the wavelength of the dielectric. .
In the present embodiment, power is supplied to the antenna body 40 from the circuit board 25 through a connection line.

  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 receiving unit 26 performs wireless communication processing such as satellite signal reception, GPS satellite 20 capture, 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 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 and the circuit board 25 are paired and function as an antenna as a whole. At this time, by setting the electrical length of the antenna body 40 and the circuit board 25 to ¼ wavelength of the satellite signal, it is possible to maintain an appropriate reception performance for the satellite signal to be received. Further, in the present embodiment, the antenna body 40 is a chip antenna having a dielectric, so that the size can be reduced by shortening the wavelength of the dielectric. In addition, since the circuit board 25 also includes a dielectric, it is only necessary to provide a wiring pattern whose size is shortened by the dielectric constant of the dielectric, thereby reducing the size.

  In particular, in the electronic timepiece 100 according to this embodiment, the radiation directivity is such that the direction in which the center position of the antenna body 40 is located when viewed from the center of the circuit board 25 is the maximum radiation direction. By placing it in the 6 o'clock to 10 o'clock range or the 12 o'clock to 4 o'clock range, the antenna gain can be reduced when the wearer is in the position of lowering his wrist or placing his hand in front of his body. The large direction coincides with the zenith direction, and the reception performance is sufficiently exhibited. In the present invention, the center position of the antenna body 40 indicates the center position of a three-dimensional shape as shown in FIGS. 6 (a) and 6 (b).

  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. 6C 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 center position of the antenna body 40 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 direction in which the antenna gain is large is in the zenith direction is high.

  8-10 is explanatory drawing of the radiation pattern of the antenna comprised by the antenna body 40 and the circuit board 25. FIG. FIG. 8 is an explanatory diagram showing a coordinate system centered on the antenna body 40 and the circuit board 25. The center point of the circuit board 25 is the origin, the horizontal plane including the watch surface is the XY plane, and the antenna The state which installed the center position of the body 40 on the X-axis is shown. The radiation pattern shown in FIG. 9 is the radiation pattern in the XY plane shown in FIG. 8, and the antenna body 40 and the circuit board 25 are positioned on the X axis near the origin. The radiation pattern shown in FIG. 10 is a radiation pattern in the ZY plane, and the center position of the antenna body 40 is disposed 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 the antenna body 40 and the circuit board 25 are positioned on the X axis, the X axis direction is the maximum radiation direction and the antenna gain is maximum, and the Y axis direction is the null value and the antenna gain. Is low. Therefore, as in the present invention, when the center position of the antenna body 40 is located in the range of 6 o'clock to 10 o'clock or 12 o'clock to 4 o'clock, reception is performed while wearing a wrist watch on the arm and being outdoors. In addition, 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. However, in this embodiment, the exterior case 80 is a non-conductive member, so there is no such influence. 85 is separated by the circuit board 25 and the like, and has an appropriate distance from the antenna body 40, so that it can function effectively as a reflector without deteriorating antenna characteristics.

  In the present embodiment, a plate-shaped antenna body having electrodes formed on the dielectric surface is used. However, the present invention is not limited to this. For example, a rectangular patch antenna that operates with linearly polarized waves is used. It may be used. As the patch antenna, an element formed by etching an element of an inverted-F antenna or an inverted-L antenna into a metal pasted on an insulating substrate can be used. In the case of a patch antenna, since a ground plane is required on the lower surface of the antenna, the pattern of the circuit board 25 is expanded on the lower surface of the antenna.

  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 plan view of an electronic timepiece 200 with built-in antenna (electronic timepiece 200) according to the second embodiment of the present invention, and FIG. 12 is an electronic timepiece with built-in antenna according to the second embodiment of the present invention. 2 is a partial cross-sectional view of 200 (electronic timepiece 200). The electronic timepiece 200 is different from the electronic timepiece 100 in that the solar panel 88 is provided with a notch 88a at a location corresponding to the position of the antenna body 40.

  Specifically, as shown in FIG. 11, in the present embodiment, the solar panel 88 is provided with a cutout portion 88 a that is formed by cutting out a portion that overlaps the antenna body 40 in a plan view. The antenna body 41 is disposed below the notch 88a so that the antenna body 40 and the solar panel 88 do not overlap in a plane. Note that the notch 88a may be provided with a date wheel 15 formed of plastic and displaying a calendar. The date wheel 15 is a ring-shaped plate member, and rotates in a plane perpendicular to the paper surface in FIG.

  The antenna body 41 is a dielectric such as ceramic, but may be formed by insert molding using a plastic mixed with a dielectric. In the present embodiment, an antenna electrode serving as a feeding point is integrally formed on the surface of a dielectric having a rectangular cross section, and one electrode is in contact with the inner surface of the ground plane 38 or the outer case 80, The other electrode is in contact with the circuit board 25.

  In the second embodiment, the exterior case 80 is made of metal, and the exterior case 80 and the metal back cover 85 are made to function as a ground plate. That is, the ground potential of the GPS receiver 26 is connected to the back cover 85 through the metal outer case 80. For power feeding to the antenna body 41, unbalanced power feeding is performed through the circuit board 25 on the antenna electrode on the surface of the antenna body 41.

  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 body 40 and the solar panel 88 are configured so as not to overlap with each other in a plan view, thereby preventing deterioration of reception performance due to the influence of an aluminum electrode having a thickness of several μm provided on the lower surface of the solar panel. be able to. Moreover, the area of the solar panel 88 can be secured to the maximum to increase the amount of power generation.

  In the present embodiment, since the exterior case 80 and the back cover 85 function as a ground plate through the antenna electrode (feeding point) on the side of the antenna body 41, the feeding point connected to the circuit board 25 is made one. Thus, the structure can be simplified and the cost can be reduced, and the degree of freedom of the position where the feeding point is arranged can be increased.

  100, 200 ... Electronic clock with built-in antenna (electronic clock), 40, 41 ... antenna body, 11 ... dial, 12 ... pointer shaft, 13 (13a, 13b, 13c) ... pointer, 25 ... circuit board, 26 ... GPS Receiving part, 30 ... drive mechanism, 80 ... exterior case, 81 ... bezel, 84 ... cover glass, 85 ... back cover, 87, 88 ... solar panel.

Claims (6)

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;
A circuit board housed in the outer case and provided with a wireless communication circuit for performing wireless communication;
An antenna body housed in the exterior case, connected to the circuit board, and fed unbalanced from the wireless communication circuit;
The antenna built-in type electronic timepiece, wherein a center position of the antenna body is 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. The antenna built-in electronic timepiece has one of the two openings of the outer case covered with a cover glass, and the other opening is covered with a back cover.
2. The antenna built-in electronic timepiece according to claim 1, wherein the antenna body is disposed on the cover glass side of the circuit board, and the wireless communication circuit is disposed on the back cover side.   The electronic timepiece with built-in antenna according to claim 1 or 2, wherein the electrical length of the antenna body and the circuit board is a quarter wavelength of a received radio wave. The antenna built-in electronic timepiece further includes a solar panel for photovoltaic power generation,
4. The antenna built-in type according to claim 1, wherein the solar panel has a cutout portion overlapping the antenna body in a plan view as viewed from the display direction of the time display unit. 5. Electronic clock.   The electronic timepiece with a built-in antenna according to any one of claims 1 to 4, wherein the back cover is made of metal. 6. The antenna built-in type electronic timepiece according to claim 1, wherein the antenna body is a chip antenna or a patch antenna.

Images