Electronic clock

Abstract

To provide an electronic watch in which a holding surface of a watch case holding a cover glass is formed of a conductive material, and that can improve antenna performance.SOLUTION: An electronic watch includes a conductive case, a cover member that is attached to the case, a hand, a hand shaft to which the hand is attached, and an antenna that is disposed to overlap the cover member in plan view from a first direction parallel to an axial direction of the hand shaft and receives a predetermined radio wave. The cover member is made of a material that shortens a wavelength of the radio wave, the case includes a facing surface facing a side surface of the cover member and arranged within a predetermined dimension from the side surface, and in the first direction, a height dimension from an end portion of the facing surface farthest from the antenna to a farthest portion of the cover member farthest from the antenna is equal to or greater than 1 / 60 of the wavelength shortened by the cover member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electronic timepiece with a built-in antenna. [Background technology]

[0002] BACKGROUND ART Among small electronic timepieces such as wristwatches, there are known electronic timepieces with built-in antennas that receive satellite signals (see Patent Document 1). The electronic timepiece in Patent Document 1 includes a watch case, a dial and dial ring placed inside the watch case, and an antenna. The watch case has a case and bezel made of a conductive material, and a crystal attached to the bezel. It is disclosed that at least one of the dial, dial ring, and cover crystal is a dielectric material that is positioned closer to the surface of the watch than the antenna and is located within a predetermined distance from the antenna that is set according to the wavelength of the radio waves received by the antenna. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-47144 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electronic timepiece, if the holding surface of the watch case that holds the cover crystal is made of a conductive material, the case can affect reception sensitivity. [Means for solving the problem]

[0005] The electronic timepiece disclosed herein comprises a conductive case, a cover member attached to the case, hands, a stem to which the hands are attached, and an antenna that is arranged to overlap the cover member in a plan view from a first direction parallel to the axial direction of the stem and receives predetermined radio waves, wherein the cover member is made of a material that shortens the wavelength of the radio waves, the case has an opposing surface that faces a side of the cover member and is arranged within a predetermined distance from the side, and the height dimension in the first direction from the end of the opposing surface farthest from the antenna to the farthest part of the cover member farthest from the antenna is 1 / 60 or more of the wavelength shortened by the cover member.

[0006] The electronic timepiece disclosed herein comprises a conductive case, a cover member attached to the case, hands, a stem to which the hands are attached, and an antenna that is arranged to overlap the cover member in a plan view from a first direction parallel to the axial direction of the stem and that receives predetermined radio waves, the cover member being made of a material that shortens the wavelength of the radio waves, the case having an opposing surface that faces a side of the cover member and is arranged within a predetermined dimension from the side, and a recess that opens into the opposing surface and the surface of the case, a non-conductive decorative plate being arranged in the recess, and the farthest part of the cover member that is farthest from the antenna in the first direction is farther from the antenna than the end of the opposing surface that is farthest from the antenna. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a front view showing an electronic timepiece according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the electronic timepiece. [Figure 3] FIG. 2 is an exploded perspective view showing the main parts of the electronic timepiece. [Figure 4] FIG. 2 is an exploded perspective view showing the main parts of the electronic timepiece. [Figure 5] FIG. 2 is a perspective view showing the main part of the planar antenna of the electronic timepiece. [Figure 6] FIG. 2 is a perspective view showing the main part of the planar antenna of the electronic timepiece. [Figure 7] FIG. 2 is a block diagram showing a circuit configuration of the electronic timepiece. [Figure 8] FIG. 4 is a diagram showing the current distribution in the cover crystal of the electronic timepiece. [Figure 9] 10 is a graph showing the relationship between the glass thickness of the cover glass and the antenna radiation efficiency. [Figure 10] 10 is a graph showing the relationship between the distance between the cover glass and the planar antenna and the antenna radiation efficiency. [Figure 11] FIG. 10 is a cross-sectional view showing an electronic timepiece according to a second embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing an electronic timepiece according to a third embodiment. [Figure 13] 10 is a graph showing the relationship between the shape and thickness of the cover glass and the antenna radiation efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0008] [First embodiment] An electronic timepiece 1 according to a first embodiment will be described below with reference to the drawings. In this embodiment, the crystal 15 side of the electronic timepiece 1 will be referred to as the front side or upper side, and the back cover 14 side will be referred to as the back side or lower side. The electronic watch 1 of this embodiment has a built-in planar antenna 50 (described later) and is configured to receive satellite signals from multiple positioning information satellites, such as GPS satellites and quasi-zenith satellites, that orbit the Earth in a predetermined orbit, to obtain satellite time information and correct the internal time information.

[0009] 1 and 2, the electronic timepiece 1 has a case 10 that houses a dial 2, a movement 20, an hour hand 31, a minute hand 32, a second hand 33, a planar antenna 50, etc. The electronic timepiece 1 also has a crown 6 for external operation and two buttons 7A and 7B.

[0010] The dial 2 is formed into a disk shape using a non-conductive material. The dial 2 in this embodiment is made of polycarbonate resin with a relative dielectric constant of 3. A through hole 2A is formed in the center of the plane of the dial 2, and three coaxial pivots 35, 36, and 37 are arranged in the through hole 2A. Hour hand 31 is attached to pivot 35, minute hand 32 is attached to pivot 36, and second hand 33 is attached to pivot 37. The pivots 35, 36, and 37 and the hour hand 31, minute hand 32, and second hand 33 are made of conductive metal members. A rectangular date window 2B is provided at the 3 o'clock position on the dial 2. A date wheel 5 is located on the back side of the dial 2 and can be seen through the date window 2B. The hour hand 31, minute hand 32, second hand 33, and date wheel 5 are driven via a step motor and gear train, which will be described later.

[0011] In this embodiment, the direction perpendicular to the surface of the dial 2, i.e., the axial direction of the pointer shafts 35 to 37, is defined as the first direction, and the direction perpendicular to this first direction is defined as the second direction. Furthermore, in this embodiment, a plan view means that the electronic timepiece 1 is viewed from the first direction, and a side view means that the electronic timepiece 1 is viewed from the second direction.

[0012] [Exterior structure of electronic watch] Case 10 comprises case main body 11 and back cover 14. Case main body 11 comprises a cylindrical case 12 and a ring-shaped bezel 13 attached to the front side of case 12. Note that in this embodiment, case 12 and back cover 14 are constructed as separate bodies, but this is not a limitation and a one-piece case in which case 12 and back cover 14 are integrated is also possible. Also, in this embodiment, case 12 and bezel 13 are constructed as separate bodies, but this is not a limitation and a structure in which case 12 and bezel 13 are integrated is also possible, which has the advantage of being less expensive. The case 12, bezel 13, and back cover 14 are made of a metallic material, such as stainless steel, titanium alloy, aluminum, or brass, that is, a conductive material.

[0013] A cover crystal 15, which is a cover member, is attached to the bezel 13 of the case 10. The cover crystal 15 is formed in a disk shape, and its front surface, i.e., upper surface 151, and its back surface, i.e., lower surface 152, are flat surfaces parallel to the second direction. Hereinafter, a cover crystal whose upper and lower surfaces are parallel to the second direction will be referred to as a flat glass. The cover crystal 15 is made of a transparent material such as mineral glass, sapphire glass, or organic glass. Mineral glass is glass made of silica (silicon dioxide: SiO2), sapphire glass is glass made of alumina (aluminum oxide: Al2O3), and organic glass is a synthetic resin material such as acrylic. The cover crystal 15 of this embodiment is made of plate-shaped sapphire glass. Sapphire glass has a relative dielectric constant of approximately 9 to 11 and is made of single-crystal sapphire made of high-purity alumina. Sapphire glass is characterized by its high hardness and scratch resistance, its extremely smooth surface, excellent light transmittance, and high visibility. The crystal diameter of the cover crystal 15 is determined by the size of the electronic timepiece 1, and the thickness of the cover crystal 15 is determined by the relationship between the crystal diameter and waterproof performance. For example, if the electronic timepiece 1 is waterproof to 10 atmospheres, the thickness of the cover crystal 15 is approximately 1.5 mm, and if it is waterproof to 20 atmospheres, the thickness of the cover crystal 15 is approximately 2.6 to 2.8 mm. Since the electronic timepiece 1 of this embodiment is waterproof to 20 atmospheres, the thickness of the cover crystal 15 is 2.6 to 2.8 mm. Since the thickness of the cover crystal 15 is constant, it coincides with the maximum thickness. Therefore, the maximum thickness of the cover crystal 15 is 2.6 to 2.8 mm, which, as described below, is 1 / 30 of the wavelength shortened by the cover crystal 15, or 2.0 mm or more. Furthermore, the side surface 153 of the cover crystal 15 is a circumferential surface parallel to the first direction.

[0014] [Internal structure of an electronic watch] Next, the internal structure of the case 10 of the electronic timepiece 1 will be described. As shown in FIG. 2, the case 10 accommodates the dial 2, a dial ring 16, a movement 20, and the like.

[0015] The dial ring 16 is made of a non-conductive material and has a ring shape in plan view, similar to the dial 2, and is arranged along the outer periphery of the dial 2. In this embodiment, the dial ring 16 is made of polycarbonate resin with a relative dielectric constant of 3. The dial ring 16 covers the outer periphery of the dial 2 so that the outer periphery of the dial 2 is not visible due to the dial ring 16.

[0016] 2, 3, and 4, the movement 20 comprises a date indicator 5, a main plate 21, a train wheel bridge 22, a drive mechanism 23, a secondary battery 24, a solar panel 25, a first magnetic shield 26 that also serves as an hour wheel holder, a planar antenna 50, an LED board 60, a circuit board 70, a second magnetic shield 81, a circuit holder 82, etc. Note that the date indicator 5, train wheel bridge 22, first magnetic shield 26, LED board 60, and second magnetic shield 81 are not shown in FIG.

[0017] The main plate 21 is made of a non-conductive material such as plastic. Between the main plate 21 and the dial 2, as shown in Figures 3 and 4, there are arranged a solar panel 25, a planar antenna 50, a date indicator 5, an LED board 60, and a first magnetic shield 26. That is, the solar panel 25 is arranged on the back side of the dial 2, which is the surface facing the main plate 21, the planar antenna 50 is arranged on the back side of the solar panel 25, the date indicator 5 and LED board 60 are arranged on the back side of the planar antenna 50, and the first magnetic shield 26 is arranged on the back side of the date indicator 5 and LED board 60. Between the main plate 21 and the back cover 14, there are arranged a train wheel bridge 22, a drive mechanism 23, a secondary battery 24, a circuit board 70, a second magnetic shield 81, and a circuit holder 82.

[0018] As shown in Figure 4, the train wheel bridge 22 comprises two train wheel bridges: a first train wheel bridge 22A that supports the train wheel that drives the hour hand 31, minute hand 32, and second hand 33, and a second train wheel bridge 22B that supports the train wheel that drives the date wheel 5. However, they may also be made into a single train wheel bridge.

[0019] Drive mechanism 23 is attached to the back of main plate 21, and drives hour hand 31, minute hand 32, second hand 33, and date indicator 5. That is, as shown in FIG. 3 , drive mechanism 23 has a first step motor 231 and a first wheel train that drive hour hand 31, a second step motor 232 and a second wheel train that drive minute hand 32, a third step motor 233 and a third wheel train that drive second hand 33, and a fourth step motor 234 and a fourth wheel train that drive date indicator 5. The first wheel train includes a stem 35 to which hour hand 31 is attached. The second wheel train includes a stem 36 to which minute hand 32 is attached. The third wheel train includes a stem 37 to which second hand 33 is attached. In the movement 20, a winding stem 260 connected to the crown 6 is disposed at the 3 o'clock position of the dial 2, and a switching mechanism 261 such as a loveseat is disposed around the winding stem 260. In addition, the step motors 231 to 234 are disposed in positions that do not overlap with the secondary battery 24 in the plan view.

[0020] 3, the base plate 21 and the drive mechanism 23 are disposed between the LED board 60 and the circuit board 70. In addition, a second magnetic shield 81 and a circuit holder 82 are disposed on the back surface of the circuit board 70. As shown in FIG. 4, three light emitting elements 611, 612, and 613 each made of a light emitting diode are mounted on the rear surface of the LED substrate 60, which faces the base plate 21. Circuit elements such as semiconductor integrated circuits (ICs), resistors, and capacitors are mounted on both the front and back sides of circuit board 70. Three light receiving elements 711, 712, and 713 made up of phototransistors and circuit elements 741, 742, and 743 are mounted on the front side of circuit board 70, i.e., the side facing dial 2, as shown in Figure 3. These light emitting elements 611 to 613 and light receiving elements 711 to 713 are used to detect the position of each hand.

[0021] In this embodiment, a high-potential power supply voltage VDD and a low-potential power supply voltage VSS are supplied to the circuit board 70 via a secondary battery 24 and a constant voltage circuit (not shown). In this embodiment, the power supply voltage VDD is set to ground potential. Alternatively, the power supply voltage VSS may be set to ground potential. The LED substrate 60 and the circuit substrate 70 are electrically connected by conductive members 651, 652, 653, and 654, each of which is made up of a coil spring, and thus power is supplied to the light emitting elements 611, 612, and 613.

[0022] As shown in FIG. 3, the secondary battery 24 is a button-type lithium ion battery formed in a circular shape when viewed from above, and is disposed in a cutout portion 71 of the circuit board 70. Solar panel 25 is a solar cell panel used in wristwatches, and may be, for example, a film-type solar cell in which an amorphous silicon thin film is laminated on a resin film substrate. Solar panel 25 has through-holes 25A through which pivots 35-37 are inserted, and two electrode terminals. As shown in FIG. 4, these electrode terminals and circuit board 70 are electrically connected by coil springs 251 and 252. Therefore, the current generated by solar panel 25 is charged into secondary battery 24 via coil springs 251 and 252 and circuit board 70.

[0023] [Flat antenna] The planar antenna 50 is an antenna that receives satellite signals from GPS satellites, and in this embodiment is configured as a planar inverted-F antenna. The planar antenna 50 is disposed so as to overlap the cover glass 15 in a planar view. As shown in FIG. 2 , the planar antenna 50 includes a dielectric substrate 51, a plate-shaped first conductor element 52, a second conductor element 53 disposed so as to overlap the first conductor element 52 in a planar view, a short-circuiting portion 54 shorting the first conductor element 52 and the second conductor element 53, and a plate-shaped first magnetic shield 26 disposed so as to overlap the first conductor element 52 in a planar view. The first conductor element 52 and the second conductor element 53 can be formed of thin metal plates such as copper or iron alloy, but in this embodiment, they are formed of a metal coating formed on the surface of the dielectric substrate 51. The metal coating can be formed by plating, for example, copper, silver, nickel, aluminum, or the like. Alternatively, one of the first conductor element 52 and the second conductor element 53 may be made of metal, and the other may be formed of a base material coated with a metal coating. First magnetic shield 26 is a conductive plate made of pure iron coated with a nickel film, and as described below, comes into contact with second conductive element 53. First conductive element 52 functions as the radiating member of the planar inverted-F antenna, and second conductive element 53 and first magnetic shield 26 function as the ground member of the planar inverted-F antenna.

[0024] 5 and 6, the planar antenna 50 of this embodiment includes a dielectric substrate 51 made of synthetic resin that serves as the antenna base, with a first conductive element 52 formed on the front surface of the dielectric substrate 51, i.e., the surface facing the solar panel 25, and a second conductive element 53 formed on the back surface of the dielectric substrate 51, i.e., the surface facing the ground plane 21. In addition, a short-circuiting portion 54 that short-circuits the first conductive element 52 and the second conductive element 53 is laminated on the side surface of the dielectric substrate 51. The first conductive element 52 is formed over almost the entire surface of the dielectric substrate 51. If the dielectric substrate 51 is made of polyphenylene sulfide, liquid crystal polymer, or polycarbonate, it is easy to apply electroless plating and has a high relative dielectric constant, making it suitable as an antenna substrate.

[0025] The configuration of the planar antenna 50 of this embodiment will be described in detail with reference to Figures 3 to 6. A through-hole 50A, through which the pointer shafts 35 to 37 are inserted, is formed at the center of the plane of the planar antenna 50. That is, the through-hole 50A is formed by passing through the plate-shaped first conductive element 52, the dielectric substrate 51, and the second conductive element 53. A protrusion is formed on the back surface of the dielectric substrate 51, i.e., the surface facing the main plate 21. The protrusion comprises an inner circumference protrusion 51A formed on a position on the inner circumference side of the date indicator 5 in a plan view, and an outer circumference protrusion 51B formed on a position on the outer circumference side of the date indicator 5. The dielectric substrate 51 has the function of pressing the date indicator 5 against the main plate. A recess 51C in which the LED substrate 60 is disposed is formed in the inner circumference protrusion 51A. Furthermore, a second conductor element 53 is laminated on the bottom surface of the outer circumference protrusion 51B.

[0026] Furthermore, a power supply terminal 55 is formed on the outer peripheral protrusion 51B at a distance from the second conductive element 53. The power supply terminal 55 is electrically connected to the first conductive element 52 via the side surface of the dielectric substrate 51. One end of the feed element 56 abuts against the feed terminal 55. The other end of the feed element 56 abuts against the circuit board 70 and is electrically connected to a receiving IC mounted on the circuit board 70. Note that in FIG. 2, the feed element 56 is shown schematically as penetrating the first magnetic shield 26 and the dielectric substrate 51 to contact the first conductive element 52, but in reality, as shown in FIGS. 3 to 6, the feed terminal 55 of the first conductive element 52 extends through the side surface of the dielectric substrate 51 to the underside, and the upper end of the feed element 56 is configured to contact this feed terminal 55.

[0027] Second conductive element 53, layered on the bottom surface of outer peripheral protrusion 51B, is in contact with the surface of metal first magnetic shield 26. Second conductive element 53 and first magnetic shield 26 are electrically connected to the ground terminal of circuit board 70 via connecting element 57, and function as the ground member for the plate-shaped inverted-F antenna, as described above. Furthermore, because first magnetic shield 26 is made of metal, it also serves as a magnetic shield covering the dial 2 side of step motors 231-234. Such a planar antenna 50 also serves as a support substrate that supports the solar panel 25 made of film.

[0028] [Circuit configuration of electronic clock] FIG. 7 is a block diagram showing the circuit configuration of the electronic timepiece 1. The electronic timepiece 1 has a GPS receiving unit 300, a control display unit 400, and a power supply unit 500, all of which are arranged on a circuit board 70.

[0029] [GPS receiver] The GPS receiver 300 receives and processes satellite signals from GPS satellites via the planar antenna 50 and SAW filter 230. The SAW filter 230 is a bandpass filter that passes 1.5 GHz satellite signals. A separate LNA may be inserted between the planar antenna 50 and the SAW filter 230 to improve reception sensitivity. The SAW filter 230 may also be built into the GPS receiver 300. SAW is an abbreviation for Surface Acoustic Wave, and LNA is an abbreviation for Low Noise Amplifier.

[0030] The GPS receiver 300 processes satellite signals that have passed through the SAW filter 230, and includes an RF circuit 310, a baseband circuit 320, a crystal oscillator circuit 330 with a temperature compensation circuit, and a flash memory 340. RF is an abbreviation for Radio Frequency. The crystal oscillator circuit 330 is abbreviated as TCXO in FIG. 7.

[0031] The RF circuit 310 is a typical RF section for GPS reception that includes a PLL, VCO, LNA, mixer, IF amplifier, IF filter, A / D converter, etc. Note that PLL is an abbreviation for Phase Locked Loop, VCO is an abbreviation for Voltage Controlled Oscillator, and IF is an abbreviation for Intermediate Frequency.

[0032] The baseband circuit 320 is a typical baseband unit for GPS reception that includes a DSP, CPU, RTC, SRAM, etc. The baseband circuit 320 is also connected to a TCXO 330 and flash memory 340. Note that DSP is an abbreviation for Digital Signal Processor, CPU is an abbreviation for Central Processing Unit, RTC is an abbreviation for Real Time Clock, and SRAM is an abbreviation for Static Random Access Memory.

[0033] Baseband circuit 320 receives the digitally converted received signal from RF circuit 310, performs correlation processing, positioning calculations, etc. to acquire satellite time information and positioning data, and uses leap seconds stored in SRAM to correct the acquired satellite time information, i.e., Z count, to calculate UTC (Coordinated Universal Time), which is the time data. Baseband circuit 320 then outputs the positioning data and time data to control unit 410. The clock that forms the basis of the local oscillation signal is supplied from the TCXO 330 to the RF circuit 310 via the baseband circuit 320 .

[0034] Flash memory 340 stores a time difference database that associates location information specified by latitude and longitude with time difference information for that location. When GPS receiver 300 acquires location information in positioning mode, it acquires time difference information, i.e., the time difference from UTC, based on the location information (latitude, longitude) and outputs it to control unit 410.

[0035] [Control display section] The control display unit 400 includes a control unit (CPU) 410, a drive circuit 420 that drives the hands and the like, and a crystal oscillator 430.

[0036] The control unit 410 includes an RTC 411, a ROM 412, and a storage unit 413, and keeps time, and outputs control signals to the GPS receiving unit 300 to control its operation. The RTC 411 keeps internal time using a reference signal output from the crystal oscillator 430. Various programs executed by the control unit 410 are stored in the ROM 412. In this embodiment, the internal time kept by the RTC 411 is UTC, which is Coordinated Universal Time. If reception in the timekeeping mode or positioning mode is successful, the control unit 410 updates the RTC 411 with the UTC output from the GPS receiver unit 300. The memory unit 413 stores the satellite time information, positioning information, and time difference information output from the GPS receiving unit 300. To this end, the control unit 410 calculates the time at the current location using UTC and the time difference information, and drives the drive mechanism 23 using the drive circuit 420 to indicate the calculated time with the hour hand 31, minute hand 32, and second hand 33.

[0037] [Power supply section] The power supply unit 500 supplies power to the GPS receiving unit 300 and the control display unit 400, and includes a solar panel 25, a charge control circuit 510, a secondary battery 24, a first voltage conversion unit 520, a second voltage conversion unit 530, and a voltage detection circuit 540. The charge control circuit 510 controls the charging of the secondary battery 24 with the power generated by the solar panel 25 . The secondary battery 24 supplies driving power to the control display unit 400 via the first voltage conversion unit 520 and supplies driving power to the GPS receiving unit 300 via the second voltage conversion unit 530 . The voltage detection circuit 540 monitors the output voltage of the secondary battery 24 and outputs it to the control unit 410. Therefore, the control unit 410 can grasp the voltage of the secondary battery 24 detected by the voltage detection circuit 540 and control the reception process.

[0038] [Dielectric resonator antenna] Next, we will explain the dielectric resonator antenna (DRA) in the electronic timepiece 1. DRA is an abbreviation for Dielectric Resonator Antennas. In watches that use high frequency wireless communications such as GPS, the use of a cover glass with a high relative permittivity such as sapphire glass will activate the dielectric resonator antenna (DRA) function, improving antenna performance. The electric field of a dielectric resonator antenna is distributed and confined in a loop inside the cylindrical dielectric resonator, and the magnetic field that interlinks with this leaks out to the outside of the dielectric. Its resonant frequency differs depending on the resonant mode, but as an example, in free space it is expressed by the following equation (1), and a certain degree of glass thickness is required. Equation (1) is the equation that expresses the resonant frequency f0 of a cylindrical DRA. Note that D c is the diameter of the cylindrical dielectric resonator, and h is its thickness.

[0039]

number

[0040] The dielectric edge is important for the resonance of the DRA. That is, as shown in Figure 8, the current distribution in the cover glass 15 is significantly affected by the glass edge and bezel 13 that secure the cover glass 15 because the outer periphery of the cover glass 15 is large. For this reason, the metal case 10 to which the cover glass 15 is attached blocks radio waves, and simply increasing the thickness of the cover glass 15 does not actually improve the antenna characteristics. To enhance the effectiveness of the DRA, the metal case 10 to which the cover glass 15 is attached needs to be designed so that it does not block radio waves. The main resonance mode of the DRA is TE 011 In mode resonance, the electric field (electric field lines) are distributed in a loop shape inside the dielectric resonator and are confined, and the magnetic field (magnetic field lines) that interlink with this leak out to the outside of the resonator. For example, if a conductor such as a microstrip line is brought close to the resonator, TE 011It is possible to feed power by coupling with the magnetic field of the mode. The magnetic field leaking from this resonator is the same as the magnetic field surrounding the actual current flowing through a loop coil placed along the electric field inside the resonator, and this antenna operates in the same way as a loop antenna. There are no conductors in this resonant system, only dielectric loss and radiation loss, and since the loss of the high frequency dielectric is particularly small compared to the conductor loss, it is expected to have less internal loss than a loop antenna and higher radiation efficiency. However, if a metal of a certain size is present near the magnetic field of the DRA, a current that tries to interfere with the magnetic field caused by the DRA's resonance will flow in the metal, reducing the radiation efficiency.

[0041] For this reason, in this embodiment, as shown in FIG. 2, a recess 131 is formed in the bezel 13 that holds the cover crystal 15, and the amount of metal material present near the edge of the cover crystal 15, that is, the bezel 13, is reduced. The inner peripheral surface of the bezel 13 located below the recess 131 serves as an opposing surface 132 that faces a side surface 153 of the cover crystal 15 via a plastic packing 17. The bezel 13 also has a support piece 133 that protrudes inward from the underside of the opposing surface 132. The support piece 133 is formed around the entire periphery of the opposing surface 132 and abuts against the underside 152 of the cover crystal 15 to support the cover crystal 15. Opposing surface 132 is a surface along a first direction, which is the axial direction of pivots 35 to 37, and is a circumferential surface along the inner circumferential surface of bezel 13. Opposing surface 132 faces a side surface 153 of crystal 15 and holds crystal 15 via plastic packing 17. In this way, crystal 15 is attached to bezel 13, i.e., case 10. The distance L between the opposing surface 132 and the side surface 153 is approximately 0.4 mm. The opposing surface 132 of the bezel 13 is located within a predetermined distance from the side surface 153 of the cover crystal 15 and is a surface that faces the side surface 153. The surface that faces the side surface 153 is a surface that is disposed approximately parallel to the side surface 153. The condition of being located within a predetermined distance specifies a surface that is disposed at a distance that significantly affects the DRA. In this embodiment, the predetermined distance is set to 1 mm. The height dimension, which is the dimension along the first direction of the opposing surface 132, is approximately 1.3 mm, which is approximately half the thickness dimension 2.6 to 2.8 mm of the cover glass 15. Therefore, in the first direction, the height dimension H1 from the end of the opposing surface 132 farthest from the planar antenna 50, i.e., the upper end of the opposing surface 132, to the farthest part of the cover glass 15 farthest from the planar antenna 50 is approximately 1.3 to 1.5 mm, which is 1 / 60 or more of the wavelength shortened by the cover glass 15, as will be described later.

[0042] Recess 131 is configured to include bottom surface 1311 extending from the inner circumferential surface of ring-shaped bezel 13 toward the outer circumferential surface, and side surface 1312 extending downward from the surface of bezel 13. Side surface 1312 is a circumferential surface along the first direction. The distance between side surface 1312 and side surface 153 is larger than distance L, and is, for example, approximately 2.8 mm. Therefore, although the side surface 1312 of the recess 131 of the bezel 13 faces the side surface 153, it is spaced apart from the side surface 153 by a predetermined distance or more, and therefore has little effect on the DRA.

[0043] A decorative plate 18 is disposed in the recess 131 of the bezel 13. The decorative plate 18 is formed in a ring shape in a plan view and is made of a dielectric material with a relative permittivity of 6 or more, such as glass or ceramic. The thickness of the decorative plate 18 in FIG. 2 is, for example, 1.2 mm. This improves the effect of the DRA compared to when a metal material is also disposed in the recess 131 or when a metal bezel without the recess 131 is used. In other words, by providing the non-conductive decorative plate 18 in the recess 131 of the bezel 13, both design and antenna performance are achieved.

[0044] As described above, by forming a recess 131 in the bezel 13 that holds the cover crystal 15 and placing the decorative plate 18, which is a non-conductive material, in the recess 131, the effect of DRA resonance caused by the cover crystal 15 can be obtained when receiving satellite signals by the planar antenna 50, thereby improving the reception sensitivity of the planar antenna 50.

[0045] Next, the results of a simulation performed to confirm the effect of the DRA will be described with reference to the graph in FIG. 9 shows the relationship between the glass thickness, which indicates the thickness of the cover crystal 15 made of sapphire glass with a relative dielectric constant of 10, and the antenna radiation efficiency when the planar antenna of the first embodiment receives radio waves with a frequency of 1.575 GHz transmitted from GPS satellites. The solid line 91 shows the simulation results obtained when the recess 131 is provided in the bezel 13 and the height of the facing surface 132 that holds the cover crystal 15 is kept constant at 0.8 mm while the thickness of the cover crystal 15 is changed. The dotted line 92 shows the simulation results obtained when the recess 131 is not provided in the bezel 13 and the height of the facing surface 132 of the bezel 13 is changed according to the thickness of the cover crystal 15, i.e., when the height of the facing surface 132 of the bezel 13 is changed so that it is approximately the same height as the outermost surface of the cover crystal 15. As shown by dotted line 92 in FIG. 9 , even if the cover crystal 15 is made thicker, the antenna performance decreases if the bezel 13 also becomes thicker. On the other hand, as shown by solid line 91 in FIG. 9 , when the height of the bezel 13 is kept constant, the antenna performance improves as the thickness of the cover crystal 15 increases. The results in FIG. 9 show that when the difference in the glass thickness of the cover crystal 15 and the thickness of the metal bezel 13 exceeds 1 mm, that is, when the height of the facing surface 132 of the bezel 13 is 0.8 mm and the thickness of the cover crystal 15 is 1.8 mm or more, and the height H1 in FIG. 2 is 1 mm or more, the antenna performance improves. In other words, to obtain the resonance effect of the DRA, it is necessary to increase the height H1 by separating the upper surface 151 of the cover crystal 15 from the upper end of the facing surface 132 of the metal bezel 13. Here, the wavelength shortening formula when the relative dielectric constant of the medium is large is expressed as Equation 2. Note that λ0 is the free space wavelength, and ε r is the relative permittivity of the dielectric.

[0046]

number

[0047] The wavelength λ0 of the radio wave with a frequency of 1.575 GHz is approximately 190 mm, and the relative dielectric constant ε r is 10, so according to equation 2, the shortened wavelength λ is approximately 60.1 mm. Therefore, 1 mm is 0.0167 times (≈1 / 60) the shortened wavelength λ. The height dimension H1 from the upper end of the facing surface 132 to the farthest part of the cover glass 15 farthest from the planar antenna 50 is 1.3 to 1.5 mm, so the height dimension H1 is 1 / 60 or more of the wavelength shortened by the cover glass 15. Since the top surface 151 of the cover glass 15 is flat, the distance from the planar antenna 50 in the first direction is the same at any position on the top surface 151, and the entire top surface 151 is the farthest point.

[0048] In the case of a spherical cover crystal, as in the second and third embodiments described below, the upper surface of the cover crystal is curved upward, so the top of the cover crystal is higher than the upper surface of the bezel, and the DRA effect can be obtained in this case as well. In this case, there is no need to use a special bezel 13 with recesses 131, and design freedom is expanded. As mentioned earlier, a certain glass thickness is necessary to utilize the DRA effect through resonance of the cover glass 15. In the simulation results shown in FIG. 9, as indicated by the solid line 91, antenna performance improves when the glass thickness exceeds 2 mm. Here, the wavelength λ shortened by the cover glass 15 is 60.1 mm, and a glass thickness of 2 mm is 0.033 times (≈1 / 30) the shortened wavelength λ. Therefore, it is preferable that the maximum thickness of the cover glass 15 be 1 / 30 or more of the wavelength shortened by the cover glass 15.

[0049] To confirm the effect of the distance between the crystal 15 and the planar antenna 50 on reception characteristics, we investigated how the antenna gain of the electronic timepiece 1 changes depending on the position of the crystal 15. FIG. 10 is a graph showing the results of a simulation of how the antenna radiation efficiency changes when the distance H between the crystal 15 and the planar antenna 50 in the first direction is changed. As shown in FIG. 2, the distance H between the crystal 15 and the planar antenna 50 is the distance between the top surface of the planar antenna 50 (i.e., the top surface of the first conductive element 52) ​​and the bottom surface of the dielectric crystal 15. The distance H needs to be set so that the hand closest to the crystal 15 does not come into contact with the crystal 15. In typical timepieces with three hands (hour, minute, and second hands), the minimum value of the distance H is approximately 1.2 to 1.3 mm. FIG. 10 shows the antenna radiation efficiency when the distance H is increased, with the distance H being set to 1.3 mm as the reference, ie, 0 dB. 10, the antenna performance improves as the distance H decreases, that is, as the cover glass 15 approaches the planar antenna 50. This is because the electromagnetic coupling between the cover glass 15 and the planar antenna 50 becomes stronger.

[0050] A simulation of the antenna radiation efficiency of the planar antenna 50 without the cover glass 15 showed that it was equivalent to when the distance H was 4.5 mm. Therefore, if the distance H is set to 4.5 mm or less, the antenna gain can be improved by using the cover glass 15. Here, the wavelength λ0 of the radio waves transmitted from GPS satellites is approximately 190 mm. Since 190 mm ÷ 4.5 mm = approximately 42, the distance H should be set to 1 / 42 or less of the wavelength λ0.

[0051] [Effects of the first embodiment] According to the electronic watch 1 of this embodiment, a recess 131 is formed in the bezel 13, and the height dimension H1 from the upper end of the opposing surface 132 of the bezel 13 to the upper surface 151 of the cover crystal 15 is set to 1 / 60 or more of the wavelength of the radio waves shortened by the cover crystal 15, specifically 1 mm or more. Therefore, compared to when the opposing surface 132 of the metal bezel 13 has the same thickness dimension as the cover crystal 15, the radiation efficiency of the planar antenna 50 can be improved, and the antenna performance of the planar antenna 50 can be improved. The thickness of the cover glass 15 is set to 1 / 30 or more of the wavelength of the radio wave shortened by the cover glass 15, specifically 2 mm or more, so that the effect of the DRA can be further enhanced and the antenna performance can be further improved.

[0052] Since sapphire glass, which has a high relative dielectric constant of approximately 9 to 11, is used as cover glass 15, the effect of the DRA can be enhanced, and antenna performance can be further improved. Furthermore, since the decorative plate 18 placed in the recess 131 is made of a dielectric material with a relative dielectric constant of 6 or more, the effect of the DRA can be improved, and both design and antenna performance can be achieved.

[0053] The electronic watch 1 uses a planar antenna 50, which has a larger area overlapping with the cover crystal 15 in a planar view than other antennas such as the ring antenna and patch antenna described below, and therefore can enhance the effect of the DRA compared to other antennas.

[0054] The dielectric substrate 51 of the planar antenna 50 also serves as parts of the movement 20, such as the recess 51C that houses the LED substrate 60, the date indicator holder that holds the date indicator 5, and the support substrate for the solar panel 25, which increases the degree of freedom in movement design and is advantageous for making the electronic timepiece 1 smaller and thinner. On the other hand, the dielectric substrate 51 may be a component dedicated to the planar antenna that does not also serve other functions. The first magnetic shield 26 also serves as the grounding member for the planar antenna 50 and as an hour wheel holder, further increasing the degree of freedom in movement design and favoring the miniaturization and thinning of the electronic timepiece 1. The LED board 60 is housed in the recess 51C of the dielectric board 51 and is positioned at approximately the same height as the dielectric board 51, so the thickness of the movement 20 can be reduced and the electronic timepiece 1 can be made thinner. Since the solar panel 25 is disposed over almost the entire surface of the front side of the planar antenna 50, the power generation area can be increased.

[0055] [Second embodiment] Next, we will explain the electronic timepiece 1B of the second embodiment shown in Figure 11. The main differences between the electronic timepiece 1B of the second embodiment are that it uses a loop antenna 800 instead of the planar antenna 50, and that it uses a cover crystal 15B made of dual-curved glass instead of flat glass. Note that components similar to those of the first embodiment are given the same reference numerals and will not be described again.

[0056] Annular antenna 800 is constructed by forming antenna element 820 on an annular antenna substrate 810 made of a dielectric material by plating, silver paste printing, etc. The dielectric material that forms antenna substrate 810 can be a resin material with a high dielectric constant, with a relative dielectric constant of about 5 to 15, such as one made by mixing a ceramic dielectric material that can be used at high frequencies, such as titanium oxide, with synthetic resin and molding it. Antenna element 820 is a C-shaped loop element with a portion of the loop cut out in plan view from the cover glass 15B side, and converts electromagnetic waves into electric current. Antenna element 820 is electrically connected to circuit board 70 via feed pin 840.

[0057] The circular antenna 800 is disposed along the outer periphery of the dial 2 and the solar panel 25. In other words, the dial 2 and the solar panel 25 are disposed in the space inside the circular antenna 800. The circular antenna 800 is covered by the dial ring 16B disposed on the inner periphery of the bezel 13B.

[0058] The cover crystal 15B is a dual-curve glass with both the upper surface 151B and the lower surface 152B curved. The thickness of the cover crystal 15B is approximately 1.9 to 2.0 mm. The cover crystal 15B is held in place by a bezel 13B. Note that the bezel 13B of the electronic timepiece 1B differs from the bezel 13 of the electronic timepiece 1 in that it does not have a recess. The height dimension of a side surface 153B of the cover crystal 15B and the height dimension of an opposing surface 132B of the bezel 13B that faces the side surface 153B with the plastic packing 17 interposed therebetween are approximately the same dimension.

[0059] In a first direction parallel to the axial direction of the pivots 35-37, the crystal 15B side is defined as the upper side, and the back cover 14 side is defined as the lower side. In this case, the central position of the top surface 151B of the crystal 15B in a plan view, that is, the position overlapping with the pivots 35-37, is the uppermost position, and this uppermost position is the farthest part 155B from the annular antenna 800 in the first direction. As shown in Fig. 11, the height H2 in the first direction from the end of the facing surface 132B of the bezel 13B farthest from the annular antenna 800 to the farthest part 155B is set to be 1 / 60 or more of the wavelength shortened by the crystal 15B, specifically 1 mm or more.

[0060] [Effects of the second embodiment] The electronic timepiece 1B of the second embodiment has the same configuration as the electronic timepiece 1 of the first embodiment, and can therefore achieve the same effects. That is, in the first direction, the farthest part 155B of the cover glass 15B is positioned above the opposing surface 132B of the bezel 13B, and its height dimension H2 is set to 1 / 60 or more of the wavelength shortened by the cover glass 15B, thereby making it possible to take advantage of the effect of the DRA to improve antenna performance.

[0061] The electronic timepiece 1B uses a dual-curve cover crystal 15B and the bezel 13B does not have any recesses, which improves the versatility of the design. Since the annular antenna 800 is arranged along the outer periphery of the dial 2, the antenna can be arranged closer to the front surface than the movement 20, i.e., closer to the cover crystal 15, making it less susceptible to influence from timepiece parts such as the step motor and improving reception performance.

[0062] [Third embodiment] Next, we will explain the electronic timepiece 1C of the third embodiment shown in Figure 12. The main differences between the electronic timepiece 1C of the third embodiment are that it uses a patch antenna 900 and a curved crystal as the cover crystal 15C. Note that the same components as those of the first embodiment are given the same reference numerals and will not be described again.

[0063] The patch antenna 900 is a surface-mounted patch antenna that includes a dielectric substrate 910, a conductive antenna electrode 920, a ground electrode, and a feeding electrode. The dielectric substrate 910 is made of a rectangular ceramic, and is formed by molding barium titanate, which has a relative dielectric constant of about 100, in a press machine and then firing it. The antenna electrode 920 is disposed on the surface of the dielectric substrate 910. The ground electrode and the feeding electrode are formed by screen-printing a paste material, mainly silver, on the back surface of the dielectric substrate 910. The ground electrode functions as the ground for the patch antenna 900 and is electrically connected to the second circuit board 72, which functions as the ground plate. The feeding electrode is electromagnetically coupled to the antenna electrode 920. This eliminates the need for a feeding pin that electrically connects the feeding electrode and the antenna electrode 920. When patch antenna 900 is rectangular, one side of antenna electrode 920 resonates at half the wavelength of the radio wave. Here, because dielectric substrate 910 is made of a high dielectric material, the length of antenna electrode 920 that resonates with the radio wave can be shortened due to the wavelength shortening effect, and patch antenna 900 can be made smaller.

[0064] The cover glass 15C is made of curved glass in which an upper surface 151C is curved and a lower surface 152C is flat. In the electronic timepiece 1C, the crystal 15C side is defined as the top and the back cover 14 side as the bottom in a first direction parallel to the axial direction of the pivots 35-37. In this case, the center position of the top surface 151C of the crystal 15C in a plan view, that is, the position overlapping with the pivots 35-37, is the top, and this top is the farthest part 155C furthest from the patch antenna 900 in the first direction. For this reason, as shown in Figure 12, the height H3 in the first direction from the end of the facing surface 132C of the bezel 13C farthest from the patch antenna 900 to the farthest part 155C is set to be 1 / 60 or more of the wavelength shortened by the crystal 15C, specifically 1 mm or more. To maximize the DRA effect due to the resonance of the cover glass 15C, the thickness of the dielectric glass is necessary. If the height dimension of the side surface 153C of the cover glass 15C is a and the height dimension from the bottom surface 152C to the farthest part 155C is b, then in the cover glass 15C of this embodiment, the height dimension a is 1.0 mm and the height dimension b is 2.4 mm. The height dimension of the facing surface 132C of the bezel 13C is the same as the height dimension a of the side surface 153C of the cover glass 15C, and the height dimension H3 in the first direction from the top end of the facing surface 132C to the farthest part 155C is 1.4 mm. Therefore, the height dimension H3 is equal to or greater than 1 / 60 of the shortened wavelength.

[0065] FIG. 13 is a graph showing the simulation results of the antenna radiation efficiency depending on the shape and thickness of the cover glass. FIG. 13 shows the radiation efficiency when a 2.4 mm-thick flat cover glass 15 is used as a reference, i.e., 0 dB, and the radiation efficiency when a 1.0 mm-thick flat cover glass is used and when the cover glass 15C of the third embodiment is used. As shown in FIG. 13, the radiation efficiency is lower when a 1.0 mm-thick flat cover glass is used compared to a 2.4 mm-thick flat cover glass 15. However, the radiation efficiency of the cover glass 15C is approximately the same as that of the 2.4 mm-thick flat cover glass 15. That is, even if the thickness of the edge side surface 153C of the cover glass 15C is as thin as 1.0 mm, as long as the glass thickness in the center is 2.4 mm, the antenna performance is equivalent to that of a 2.4 mm-thick flat glass. Therefore, using a curved cover glass 15C can reduce the influence of a metal bezel 13C holding the cover glass 15C.

[0066] [Effects of the third embodiment] The electronic timepiece 1C of the third embodiment has the same configuration as the electronic timepiece 1 of the first embodiment, and can therefore achieve the same effects. That is, in the first direction, the farthest part 155C of the cover glass 15C is positioned above the opposing surface 132C of the bezel 13C, and its height dimension H3 is set to 1 / 60 or more of the wavelength shortened by the cover glass 15C, thereby making it possible to take advantage of the effect of the DRA to improve antenna performance.

[0067] The electronic timepiece 1C uses a curved cover crystal 15C and has no recesses in the bezel 13C, which improves the versatility of the design. In addition, because the electronic timepiece 1C uses curved glass, the edge of the cover crystal 15C can be made thin, allowing the electronic timepiece 1C to appear slimmer in design.

[0068] Because the patch antenna 900 is small in size in a plan view, it can be placed in a position where it does not overlap in a plan view with the secondary battery 24, step motors 231-234, wheel train, etc. This is advantageous for making the electronic timepiece 1C smaller and thinner.

[0069] [Other embodiments] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the present invention.

[0070] The combinations of cover crystal types and antenna types are not limited to those in the above-described embodiments. For example, a loop antenna 800 or patch antenna 900 may be incorporated into an electronic timepiece 1 equipped with a flat glass cover crystal 15. A planar antenna 50 or patch antenna 900 may also be incorporated into an electronic timepiece 1B equipped with a dual-curved glass cover crystal 15B. Furthermore, a planar antenna 50 or loop antenna 800 may also be incorporated into an electronic timepiece 1C equipped with a curved glass cover crystal 15C. The cover material is not limited to sapphire glass, and any dielectric material can be used as long as it has a relative dielectric constant of 6 or greater and the properties required for an electronic timepiece cover material.

[0071] The electronic timepiece may also be equipped with a rotating bezel. In this case, even if the rotating bezel does not directly hold crystal 15, if the rotating bezel has a facing surface that faces side surface 153 of crystal 15 and this facing surface is located within a predetermined distance from side surface 153, it is sufficient that the height dimension from the end of the facing surface of the rotating bezel farthest from the antenna to the farthest part of the cover member farthest from the antenna is 1 / 60 or more of the wavelength shortened by the cover member. Furthermore, the bezels 13B and 13C of the electronic timepieces 1B and 1C may also be formed with recesses similar to the bezel 13, and decorative plates may be placed therein.

[0072] In the first embodiment, the planar antenna 50 is configured to include the first magnetic shield 26, but this is not limiting. The second conductive element 53 may be formed in a plate shape with approximately the same area as the first conductive element 52, and may function as a ground member for the planar inverted-F antenna. In the above-described embodiments, the antenna receives satellite signals transmitted from GPS satellites, but the signals received by the antenna are not limited to this. For example, the antenna may receive satellite signals transmitted from satellites of other global navigation satellite systems (GNSS) such as Galileo, GLONASS, and Beidou, geostationary satellite-based augmentation systems (SBAS), and regional navigation satellite systems (RNSS) that can be searched only in specific regions, such as quasi-zenith satellites. The antenna is not limited to one that receives satellite signals, but may also be an antenna that receives other radio waves, such as Bluetooth (registered trademark), BLE (Bluetooth Low Energy), Wi-Fi (registered trademark), NFC (Near Field Communication), LPWA (Low Power Wide Area), etc. In other words, the antenna incorporated into the electronic timepieces 1, 1B, 1C can be an antenna appropriate for the type of signal to be received, the size of the timepiece, how it fits in with other components, etc.

[0073] Summary of this disclosure The electronic timepiece disclosed herein comprises a conductive case, a cover member attached to the case, hands, a stem to which the hands are attached, and an antenna that is arranged to overlap the cover member in a plan view from a first direction parallel to the axial direction of the stem and receives predetermined radio waves, wherein the cover member is made of a material that shortens the wavelength of the radio waves, the case has an opposing surface that faces a side of the cover member and is arranged within a predetermined distance from the side, and the height dimension in the first direction from the end of the opposing surface farthest from the antenna to the farthest part of the cover member farthest from the antenna is 1 / 60 or more of the wavelength shortened by the cover member. According to the electronic watch of the present disclosure, the cover member is made of a material that shortens the wavelength of radio waves, and the height dimension from the end farthest from the antenna on the opposing surface of the case to which the cover member is attached to the farthest point on the cover member farthest from the antenna is set to be 1 / 60 or more of the wavelength shortened by the cover member.In other words, the cover member has a portion that protrudes upward in the first direction beyond the opposing surface of the case, so the function of the dielectric resonator antenna using the cover member can be effectively utilized, and the antenna radiation efficiency can be improved.

[0074] In the electronic timepiece disclosed herein, the electronic timepiece comprises a dial, a drive mechanism that drives the hands, and a base plate to which the drive mechanism is attached, and the antenna comprises a plate-shaped conductive element having a through hole through which the hand stem is inserted, and it is preferable that, when viewed from the side in a second direction perpendicular to the first direction, the antenna is positioned between the dial and the base plate. In the electronic timepiece disclosed herein, the antenna is positioned between the dial and main plate and includes a through-hole for inserting the pivot, ensuring an area roughly the same as the dial when viewed in plan. This allows for a larger area to overlap with the cover member in plan view, strengthening electromagnetic coupling with the cover member and improving antenna performance.

[0075] In the electronic timepiece of this disclosure, it is preferable that the maximum thickness of the cover member is at least 1 / 30 of the wavelength shortened by the cover member. In the electronic timepiece of this disclosure, the maximum thickness of the cover member is at least 1 / 30 of the wavelength shortened by the cover member, which increases the effectiveness of the DRA and improves antenna performance.

[0076] In the electronic timepiece of this disclosure, the cover member is preferably made of a dielectric material with a relative dielectric constant of 6 or greater. In the electronic timepiece disclosed herein, the cover member has a high relative dielectric constant, which increases the effectiveness of the DRA and improves antenna performance.

[0077] In the electronic timepiece of the present disclosure, it is preferable that the case has a recess that opens onto the opposing surface and onto the surface of the case, and that a non-conductive decorative plate be placed in the recess. In the electronic timepiece disclosed herein, the case has a facing surface and a recessed portion that opens onto the surface of the case, which allows the height position of the top of the facing surface to be low and ensures a sufficient height from the facing surface to the farthest part of the cover member. This reduces the influence of the case, which is made of conductive material, on the outer edge of the cover member, increasing the effectiveness of the DRA and improving antenna performance.

[0078] In the electronic timepiece of the present disclosure, the decorative plate is preferably made of a dielectric material with a relative dielectric constant of 6 or greater. In the electronic timepiece of this disclosure, the decorative plate has a high relative dielectric constant, which improves the receiving sensitivity of the antenna.

[0079] The electronic timepiece disclosed herein comprises a conductive case, a cover member attached to the case, hands, a stem to which the hands are attached, and an antenna that is arranged to overlap the cover member in a plan view from a first direction parallel to the axial direction of the stem and that receives predetermined radio waves, the cover member being made of a material that shortens the wavelength of the radio waves, the case having an opposing surface that faces a side of the cover member and is arranged within a predetermined dimension from the side, and a recess that opens into the opposing surface and the surface of the case, a non-conductive decorative plate being arranged in the recess, and the farthest part of the cover member that is farthest from the antenna in the first direction is farther from the antenna than the end of the opposing surface that is farthest from the antenna. In the electronic timepiece disclosed herein, the case has a facing surface and a recessed portion that opens onto the surface of the case, which allows the height position of the top of the facing surface to be low and ensures a sufficient height from the facing surface to the farthest part of the cover member. This reduces the influence of the case, which is made of conductive material, on the outer edge of the cover member, increasing the effectiveness of the DRA and improving antenna performance. [Explanation of symbols]

[0080] 1...electronic watch, 1B...electronic watch, 1C...electronic watch, 2...dial, 10...case, 11...case body, 12...body, 13...bezel, 13B...bezel, 13C...bezel, 15...cover crystal, 15B...cover crystal, 15C...cover crystal, 16...dial ring, 16B...dial ring, 17...plastic gasket, 18...decorative plate, 20...movement, 21...main plate, 23...driving mechanism, 26...first antimagnetic plate, 31...hour hand, 32...minute hand, 33...second hand, 35...hand stem, 36...hand stem, 37...hand stem, 50...planar antenna, 50A...through hole, 51...dielectric substrate, 52...first conductor element, 53...second conductor element, 54...short-circuit portion, 70...circuit board, 72...second circuit board, 81...second magnetic shield, 131...recess, 132...facing surface, 132B...facing surface, 132C...facing surface, 133...support piece, 151...upper surface, 151B...upper surface, 151C...upper surface, 152...lower surface, 152B...lower surface, 152C...lower surface, 153...side surface, 153B...side surface, 153C...side surface, 155B...farthest portion, 155C...farthest portion, 800...annular antenna, 810...antenna substrate, 820...antenna element, 900...patch antenna, 910...dielectric substrate, 920...antenna electrode.

Claims

1. A conductive case; a cover member attached to the case; Guidelines and a pointer shaft to which the pointer is attached; an antenna that is arranged to overlap the cover member in a plan view seen from a first direction parallel to the axial direction of the pointer shaft, and that receives a predetermined radio wave; the cover member is made of a material that shortens the wavelength of the radio wave, the case includes an opposing surface that faces a side surface of the cover member and holds the cover member via a packing, and a recess that opens to the opposing surface and a surface of the case; a dimension in a second direction perpendicular to the first direction from the side surface of the cover member to the opposing surface is within a predetermined dimension; a non-conductive decorative plate is disposed in the recess; In the first direction, a height dimension from an end of the opposing surface farthest from the antenna to a farthest part of the cover member farthest from the antenna is 1 / 60 or more of the wavelength shortened by the cover member. An electronic watch characterized by:

2. 2. The electronic timepiece according to claim 1, The dial and a drive mechanism for driving the pointer; a base plate to which the drive mechanism is attached, the antenna includes a plate-shaped conductive element having a through hole through which the pointer shaft is inserted, In a side view seen from a second direction perpendicular to the first direction, the antenna is disposed between the dial and the main plate. An electronic watch characterized by:

3. 3. The electronic timepiece according to claim 1, The maximum thickness of the cover member is 1 / 30 or more of the wavelength shortened by the cover member. An electronic watch characterized by:

4. 4. The electronic timepiece according to claim 1, The cover member is made of a dielectric material having a relative dielectric constant of 6 or more. An electronic watch characterized by:

5. 2. The electronic timepiece according to claim 1, The decorative plate is made of a dielectric material having a relative dielectric constant of 6 or more. An electronic watch characterized by:

6. A conductive case; a cover member attached to the case; Guidelines and a pointer shaft to which the pointer is attached; an antenna that is arranged to overlap the cover member in a plan view seen from a first direction parallel to the axial direction of the pointer shaft, and that receives a predetermined radio wave; the cover member is made of a material that shortens the wavelength of the radio wave, the case includes an opposing surface that faces a side surface of the cover member and holds the cover member via a packing, and a recess that opens to the opposing surface and a surface of the case; a dimension in a second direction perpendicular to the first direction from the side surface of the cover member to the opposing surface is within a predetermined dimension; a non-conductive decorative plate is disposed in the recess; In the first direction, the farthest portion of the cover member from the antenna is farther from the antenna than the farthest end of the opposing surface from the antenna. An electronic watch characterized by:

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