Electronic timepiece

Abstract

The present application provides an electronic timepiece, capable of forming a holding surface of a holding glass cover of a timepiece housing by a conductive material, capable of improving antenna performance. An electronic timepiece characterized by having: a housing of a conductive property; a cover member mounted to the housing; a hand; a hand shaft on which the hand is mounted; and an antenna that receives a prescribed electric wave and is configured to overlap the cover member when viewed from above in a first direction parallel to an axial direction of the hand shaft, the cover member being composed of a material that shortens a wavelength of the electric wave, the housing having an opposing surface that opposes a side surface of the cover member and is disposed at a position within a prescribed dimension from the side surface, a height dimension from an end of the opposing surface farthest from the antenna to a farthest portion of the cover member farthest from the antenna in the first direction being 1 / 60 or more of the wavelength shortened by the cover member.

Description

TECHNICAL FIELD

[0001] The present application relates to an electronic timepiece in which an antenna is built in. BACKGROUND

[0002] In a small electronic timepiece such as a wristwatch, an antenna built-in electronic timepiece in which an antenna that receives a satellite signal is built in is known (see Patent Literature 1).

[0003] The electronic timepiece of Patent Literature 1 has a timepiece case, a dial and a dial ring arranged in the timepiece case, and an antenna. The timepiece case has a case body and a bezel made of an electrically conductive material, and a glass cover attached to the bezel.

[0004] It is disclosed that at least one of the dial, the dial ring, and the glass cover is a dielectric arranged on the timepiece front side than the antenna and arranged within a prescribed distance set in accordance with a wavelength of an electric wave received by the antenna with respect to the antenna.

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2021-47144

[0006] With respect to the timepiece case of the electronic timepiece, in a case where a holding surface that holds the glass cover is formed of an electrically conductive material, the reception sensitivity is sometimes reduced due to the influence of the case. SUMMARY

[0007] The electronic timepiece of the present disclosure is characterized by including: an electrically conductive case; a cover member attached to the case; a hand; a hand shaft on which the hand is attached; and an antenna that receives a prescribed electric wave and is arranged so as to overlap the cover member when viewed from above in a first direction parallel to an axial direction of the hand shaft, the cover member being made of a material that shortens a wavelength of the electric wave, the case having an opposing surface that opposes a side surface of the cover member and is arranged at a position within a prescribed dimension from the side surface, and a height dimension from an end portion of the opposing surface farthest from the antenna to a farthest portion of the cover member farthest from the antenna in the first direction being 1 / 60 or more of the wavelength shortened by the cover member.

[0008] The electronic timepiece of the present disclosure is characterized by including: a case that is electrically conductive; a cover member that is attached to the case; a hand; a hand shaft on which the hand is attached; and an antenna that receives a prescribed radio wave and is configured to overlap the cover member when viewed from above in a first direction parallel to an axial direction of the hand shaft, the cover member being composed of a material that shortens a wavelength of the radio wave, the case including: an opposing surface that opposes a side surface of the cover member and is disposed at a position within a prescribed distance from the side surface; and a recess that opens toward the opposing surface and a front surface of the case, a non-conductive decorative plate being disposed in the recess, in the first direction, a farthest portion of the cover member that is farthest from the antenna being farther from the antenna than an end portion of the opposing surface that is farthest from the antenna. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a front view showing an electronic timepiece of a first embodiment.

[0010] Figure 2 is a cross-sectional view showing the electronic timepiece.

[0011] Figure 3 is an exploded perspective view showing a main portion of the electronic timepiece.

[0012] Figure 4 is an exploded perspective view showing a main portion of the electronic timepiece.

[0013] Figure 5 is a perspective view showing a main portion of a planar antenna of the electronic timepiece.

[0014] Figure 6 is a perspective view showing a main portion of a planar antenna of the electronic timepiece.

[0015] Figure 7 is a block diagram showing a circuit structure of the electronic timepiece.

[0016] Figure 8 is a graph showing a current distribution in a glass cover of the electronic timepiece.

[0017] Figure 9 is a graph showing a relationship between a glass thickness of the glass cover and an antenna radiation efficiency.

[0018] Figure 10 is a graph showing a relationship between a distance between the glass cover and the planar antenna and the antenna radiation efficiency.

[0019] Figure 11 is a cross-sectional view showing an electronic timepiece of a second embodiment.

[0020] Figure 12is a sectional view showing the electronic timepiece of the third embodiment.

[0021] Figure 13 is a graph showing the relationship between the shape and thickness of the glass cover and the antenna radiation efficiency.

[0022] Explanation of Reference Numerals

[0023] 1: electronic timepiece; 1B: electronic timepiece; 1C: electronic timepiece; 2: dial; 10: case; 11: case main body; 12: bezel; 13: bezel; 13B: bezel; 13C: bezel; 15: glass cover; 15B: glass cover; 15C: glass cover; 16: dial ring; 16B: dial ring; 17: plastic gasket; 18: decorative plate; 20: movement; 21: bottom plate; 23: drive mechanism; 26: first magnetic resistance plate; 31: hour hand; 32: minute hand; 33: second hand; 35: hand shaft; 36: hand shaft; 37: hand shaft; 50: planar antenna; 50A: through hole; 51: dielectric substrate; 52: first conductor element; 53: second conductor element; 54: short-circuit portion; 70: circuit substrate; 72: second circuit substrate; 81: second magnetic resistance plate; 131: recessed portion; 132: opposing surface; 132B: opposing surface; 132C: opposing 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: loop antenna; 810: antenna base material; 820: antenna element; 900: patch antenna; 910: dielectric base material; 920: antenna electrode. DETAILED DESCRIPTION

[0024] [First Embodiment]

[0025] Hereinafter, the electronic timepiece 1 of the first embodiment will be described with reference to the drawings. In the present embodiment, the glass cover 15 side of the electronic timepiece 1 is set as the front side or upper side, and the back cover 14 side is set as the back side or lower side.

[0026] The electronic timepiece 1 of the present embodiment is configured to incorporate the planar antenna 50 described later, receive satellite signals from a plurality of GPS satellites or quasi-zenith satellites or the like that orbit at a prescribed orbit above the earth, acquire satellite time information, and be able to correct internal time information.

[0027] As Figure 1 and Figure 2As shown, the electronic timepiece 1 has a case 10 that houses a dial 2, a movement 20, a hour hand 31, a minute hand 32, a second hand 33, a planar antenna 50, and the like. Also, the electronic timepiece 1 has a stem 6 for external operation and two buttons 7A, 7B.

[0028] The dial 2 is formed in a circular plate shape from a non-conductive member. The dial 2 of the present embodiment is formed from a polycarbonate resin having a relative dielectric constant of 3.

[0029] A through hole 2A is formed in the planar center of the dial 2, and three pointer shafts 35, 36, 37 are disposed coaxially in the through hole 2A. The hour hand 31 is attached to the pointer shaft 35, the minute hand 32 is attached to the pointer shaft 36, and the second hand 33 is attached to the pointer shaft 37. The pointer shafts 35, 36, 37 and the hour hand 31, the minute hand 32, the second hand 33 are formed from a conductive member of metal.

[0030] A rectangular date window 2B is provided at the 3 o'clock position of the dial 2. A date wheel 5 is disposed on the back surface side of the dial 2, and the date wheel 5 is visible from the date window 2B. The hour hand 31, the minute hand 32, the second hand 33, and the date wheel 5 are driven via a stepping motor and a gear train described later.

[0031] In the present embodiment, the direction perpendicular to the front surface of the dial 2, that is, the axial direction of the pointer shafts 35 to 37 is set as the first direction, and the direction perpendicular to the first direction is set as the second direction. Also, in the present embodiment, looking down means observing the electronic timepiece 1 from the first direction, and looking sideways means observing the electronic timepiece 1 from the second direction.

[0032] [External structure of electronic timepiece]

[0033] The case 10 has a case main body 11 and a back cover 14. The case main body 11 has a cylindrical case body 12 and a ring-shaped bezel 13 provided on the front surface side of the case body 12. Also, in the present embodiment, the case body 12 is formed separately from the back cover 14, but is not limited thereto, and can be a single-piece case in which the case body 12 and the back cover 14 are integrated. Also, in the present embodiment, the case body 12 is formed separately from the bezel 13, but is not limited thereto, and a configuration in which the case body 12 and the bezel 13 are integrated can be used, in which case the advantage of being able to achieve a low price is obtained.

[0034] The case body 12, the bezel 13, and the back cover 14 are made of a metal material, that is, a conductive material, such as stainless steel, titanium alloy, aluminum, brass, and the like.

[0035] A glass cover 15, serving as a cover component, is mounted on the bezel 13 of the housing 10. The glass cover 15 is formed in a circular plate shape, with its front (upper surface 151) and back (lower surface 152) forming planes parallel to a second direction. Hereinafter, the glass cover with its upper and lower surfaces parallel to the second direction will be referred to as flat glass. Furthermore, the glass cover 15 is made of transparent materials such as mineral glass, sapphire glass, or acrylic glass. Mineral glass is glass made of silicon dioxide (SiO2), sapphire glass is glass made of aluminum oxide (Al2O3), and acrylic glass is made of synthetic resin materials such as acrylic acid. In this embodiment, the glass cover 15 is composed of plate-shaped sapphire glass. The relative permittivity of sapphire glass is approximately 9 to 11, and it is formed using single-crystal sapphire made of high-purity aluminum oxide. Sapphire glass is characterized by high hardness, resistance to damage, a very smooth surface after processing, excellent light transmission, and high visibility.

[0036] The diameter of the glass cover 15, i.e., the glass diameter, is determined by the size of the electronic clock 1, and the thickness of the glass cover 15 is determined by the relationship between the glass diameter and the waterproof performance. For example, when the electronic clock 1 has a waterproof rating of 10 ATM, the thickness of the glass cover 15 is approximately 1.5 mm; when it has a waterproof rating of 20 ATM, the thickness of the glass cover 15 is approximately 2.6 to 2.8 mm. The electronic clock 1 of this embodiment has a waterproof rating of 20 ATM, therefore the thickness of the glass cover 15 is 2.6 to 2.8 mm. Since the thickness of the glass cover 15 is constant, it is consistent with the maximum thickness. Therefore, the maximum thickness of the glass cover 15 is 2.6 to 2.8 mm, which, as will be described later, is 1 / 30th of the wavelength shortened by the glass cover 15, i.e., 2.0 mm or more. Furthermore, the side surface 153 of the glass cover 15 is formed as a circumferential surface parallel to the first direction.

[0037] [Internal structure of electronic clocks]

[0038] Next, the internal structure of the housing 10 built into the electronic clock 1 will be described.

[0039] like Figure 2 As shown, inside the housing 10, in addition to the dial 2, there are also dial ring 16, movement 20, etc.

[0040] The dial ring 16, like the dial 2, is made of non-conductive components and is ring-shaped when viewed from above, and is arranged along the outer periphery of the dial 2. In this embodiment, the dial ring 16 is formed of polycarbonate resin with a relative permittivity of 3.

[0041] Dial ring 16 covers the outer periphery of the upper surface of dial 2, and the outer periphery of dial 2 is not visible due to dial ring 16.

[0042] like Figure 2 , Figure 3 ,Figure 4 As shown, the movement 20 includes a date wheel 5, a base plate 21, a wheel train clamping plate 22, a drive mechanism 23, a secondary battery 24, a solar panel 25, a first magnetic plate 26 that also serves as a time wheel pressure plate, a planar antenna 50, an LED substrate 60, a circuit board 70, a second magnetic plate 81, and a circuit pressure plate 82. Additionally, in Figure 2 In the figure, the date wheel 5, wheel system clamp 22, first magnetic plate 26, LED substrate 60, and second magnetic plate 81 are omitted from the illustration.

[0043] The base plate 21 is formed of non-conductive components such as plastic. For example... Figure 3 as well as Figure 4 As shown, a solar panel 25, a planar antenna 50, a date wheel 5, an LED substrate 60, and a first magnetic-resistant plate 26 are arranged between the base plate 21 and the dial 2. That is, the solar panel 25 is arranged on the side of the dial 2 closest to the base plate 21, i.e., the back side; the planar antenna 50 is arranged on the back side of the solar panel 25; the date wheel 5 and the LED substrate 60 are arranged on the back side of the planar antenna 50; and the first magnetic-resistant plate 26 is arranged on the back side of the date wheel 5 and the LED substrate 60.

[0044] A wheel system clamping plate 22, a drive mechanism 23, a secondary battery 24, a circuit board 70, a second magnetic plate 81, and a circuit pressure plate 82 are arranged between the base plate 21 and the rear cover 14.

[0045] like Figure 4 As shown, the wheel train clamp 22 has two wheel train clamps: a first wheel train clamp 22A that supports the wheel train driving the hour hand 31, minute hand 32, and second hand 33, and a second wheel train clamp 22B that supports the wheel train driving the date wheel 5. However, it can also be a single wheel train clamp.

[0046] The drive mechanism 23 is mounted on the back of the base plate 21 and drives the hour hand 31, minute hand 32, second hand 33, and date wheel 5. That is, as... Figure 3 As shown, the drive mechanism 23 includes a first stepper motor 231 and a first gear train for driving the hour hand 31, a second stepper motor 232 and a second gear train for driving the minute hand 32, a third stepper motor 233 and a third gear train for driving the second hand 33, and a fourth stepper motor 234 and a fourth gear train for driving the date wheel 5. Furthermore, the first gear train includes a pointer shaft 35 for mounting the hour hand 31. The second gear train includes a pointer shaft 36 for mounting the minute hand 32. The third gear train includes a pointer shaft 37 for mounting the second hand 33.

[0047] In the movement 20, a stem 260 connected to the crown 6 is located at the 3 o'clock position on the dial 2, and a shifting mechanism 261, such as a lever, is arranged around the stem 260. Furthermore, stepper motors 231 to 234 are positioned so as not to overlap with the secondary battery 24 when viewed from above.

[0048] like Figure 3 As shown, a base plate 21 and a driving mechanism 23 are disposed between the LED substrate 60 and the circuit board 70. In addition, a second magnetic plate 81 and a circuit pressure plate 82 are disposed on the back side of the circuit board 70.

[0049] like Figure 4 As shown, three light-emitting elements 611, 612, and 613 composed of light-emitting diodes are mounted on the back side of the LED substrate 60 facing the base plate 21.

[0050] The circuit board 70 has semiconductor integrated circuits (ICs), resistors, capacitors, and other circuit components mounted on both its front and back sides. Furthermore, as... Figure 3 As shown, three light-receiving elements 711, 712, and 713, which are composed of photoelectric quartz tubes, and circuit elements 741, 742, and 743 are mounted on the front side of the circuit board 70, i.e., the side near the dial 2.

[0051] These light-emitting elements 611-613 and light-receiving elements 711-713 are used for the needle position detection of each pointer.

[0052] 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 the secondary battery 24 and a constant voltage circuit (not shown). Furthermore, in this embodiment, the power supply voltage VDD is set to ground potential. Alternatively, the power supply voltage VSS may also be set to ground potential.

[0053] The LED substrate 60 and the circuit board 70 are electrically connected by conductive components 651, 652, 653, and 654, which are made of helical springs, thereby supplying power to the light-emitting elements 611, 612, and 613.

[0054] like Figure 3 As shown, the secondary battery 24 is a button-shaped lithium-ion battery formed in a planar circular shape, disposed in the cutout portion 71 of the circuit board 70.

[0055] The solar panel 25 is a solar cell panel used in watches, such as a film-type solar cell obtained by laminating an amorphous silicon thin film on a resin film substrate. The solar panel 25 has a through hole 25A for inserting the pointer shafts 35-37 and two electrode terminals. Figure 4As shown, the electrode terminal is connected to the circuit board 70 via helical springs 251 and 252. Therefore, the current generated by the solar panel 25 is charged to the secondary battery 24 via the helical springs 251 and 252 and the circuit board 70.

[0056] [Planar Antenna]

[0057] The planar antenna 50 is an antenna for receiving satellite signals from GPS satellites, and in this embodiment it is composed of a plate-shaped inverted F-type antenna.

[0058] The planar antenna 50 is configured to overlap with the glass cover 15 when viewed from above. Additionally, as... Figure 2 As shown, the planar antenna 50 is configured to include: a dielectric substrate 51; a plate-shaped first conductor element 52; a second conductor element 53 arranged to overlap with the first conductor element 52 when viewed from above; a shorting portion 54 that shorts the first conductor element 52 and the second conductor element 53; and a plate-shaped first magnetically resistant plate 26 arranged to overlap with the first conductor element 52 when viewed from above. The first conductor element 52 and the second conductor element 53 can also be formed from thin metal plates such as copper or iron alloys, but in this embodiment, they are formed from a metal coating formed on the surface of the dielectric substrate 51. The metal coating can be formed, for example, by plating copper, silver, nickel, aluminum, etc. Alternatively, a structure can be adopted in which either the first conductor element 52 or the second conductor element 53 is made of metal, and the other is a structure in which a metal coating is applied to a substrate. The first magnetically resistant plate 26 is a conductor plate made by covering a pure iron plate with a nickel film, and as described later, it is in contact with the second conductor element 53. The first conductor element 52 functions as the radiating component of the plate-shaped inverted F-type antenna, while the second conductor element 53 and the first magnetically resistant plate 26 function as the grounding component of the plate-shaped inverted F-type antenna.

[0059] like Figure 5 as well as Figure 6 As shown, the planar antenna 50 of this embodiment includes a dielectric substrate 51 made of synthetic resin, which serves as the antenna substrate. A first conductor element 52 is formed on the front side of the dielectric substrate 51, i.e., the side facing the solar panel 25, and a second conductor element 53 is formed on the back side of the dielectric substrate 51, i.e., the side facing the base plate 21. Furthermore, a shorting portion 54 is stacked on the side of the dielectric substrate 51 to short-circuit the first conductor element 52 and the second conductor element 53. The first conductor element 52 is formed on approximately the entire front surface of the dielectric substrate 51.

[0060] If the dielectric substrate 51 is made of any one of polyphenylene sulfide, liquid crystal polymer, or polycarbonate, it is easy to perform electroless plating, and the relative permittivity can be improved, making it suitable as an antenna substrate.

[0061] based onFigures 3-6 The structure of the planar antenna 50 in this embodiment will be described in detail below. A through hole 50A is formed at the center of the planar antenna 50 for the pointer shafts 35 to 37 to pass through. That is, the through hole 50A is formed by passing through the plate-shaped first conductor element 52, the dielectric substrate 51, and the second conductor element 53.

[0062] A protrusion is formed on the back side of the dielectric substrate 51, i.e., the side facing the base plate 21. The protrusion includes: an inner peripheral protrusion 51A, which is formed on the inner peripheral side of the date wheel 5 when viewed from above; and an outer peripheral protrusion 51B, which is formed on the outer peripheral side of the date wheel 5 when viewed from above. The dielectric substrate 51 has the function of pressing the date wheel 5 against the base plate. A recess 51C for mounting the LED substrate 60 is formed in the inner peripheral protrusion 51A. Furthermore, a second conductor element 53 is stacked on the lowermost surface of the outer peripheral protrusion 51B.

[0063] Furthermore, a power supply terminal 55 is formed separately from the second conductor element 53 on the outer peripheral protrusion 51B. This power supply terminal 55 is connected to the first conductor element 52 via the side of the dielectric substrate 51.

[0064] One end of the power supply component 56 abuts against the power supply terminal 55. The other end of the power supply component 56 abuts against the circuit board 70 and is connected to the receiving IC mounted on the circuit board 70. Furthermore, in Figure 2 The diagram schematically illustrates that the power supply element 56 penetrates the first non-magnetic plate 26 and the dielectric substrate 51 to contact the first conductor element 52, but in reality, as shown in the diagram... Figures 3-6 As shown, the configuration is such that the power supply terminal 55 of the first conductor element 52 extends to the lower surface via the side of the dielectric substrate 51, and the upper end of the power supply element 56 contacts the power supply terminal 55.

[0065] The second conductor element 53, stacked on the lowermost surface of the outer peripheral protrusion 51B, makes frontal contact with the metal first magnetically resistant plate 26. The second conductor element 53 and the first magnetically resistant plate 26 are connected to the grounding terminal of the circuit board 70 via a connecting element 57, thus functioning as a grounding component for the plate-shaped inverted F-type antenna, as described above. Furthermore, since the first magnetically resistant plate 26 is made of metal, it also serves as a magnetically resistant plate covering the dial 2 sides of the stepper motors 231-234.

[0066] Such a planar antenna 50 also serves as a support substrate for supporting the film-based solar panel 25.

[0067] [Circuit Structure of Electronic Clocks]

[0068] Figure 7 This is a block diagram showing the circuit structure of electronic clock 1.

[0069] The electronic clock 1 has a GPS receiver 300, a control display 400, and a power supply 500 disposed on a circuit board 70.

[0070] [GPS receiver]

[0071] The GPS receiver 300 receives and processes satellite signals from GPS satellites via a planar antenna 50 and a SAW filter 230. The SAW filter 230 is a bandpass filter that allows 1.5 GHz satellite signals to pass through. Alternatively, an LNA (Low Noise Amplifier) ​​can be inserted between the planar antenna 50 and the SAW filter 230 to improve receiver sensitivity. Alternatively, the SAW filter 230 can be integrated within the GPS receiver 300. SAW stands for Surface Acoustic Wave, and LNA stands for Low Noise Amplifier.

[0072] 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 quartz oscillator circuit 330 with temperature compensation, and a flash memory 340. RF stands for Radio Frequency. The quartz oscillator circuit 330... Figure 7 It is marked as TCXO.

[0073] The RF circuit 310 is typically used as an RF unit for GPS receivers, incorporating a PLL, VCO, LNA, mixer, IF amplifier, IF filter, A / D converter, etc. Furthermore, PLL stands for Phase Locked Loop, VCO for Voltage Controlled Oscillator, and IF for Intermediate Frequency.

[0074] The baseband circuit 320 typically serves as the baseband unit for a GPS receiver, incorporating a DSP, CPU, RTC, and SRAM. A TCXO 330 and flash memory 340 are also connected to this baseband circuit 320. DSP stands for Digital Signal Processor, CPU for Central Processing Unit, RTC for Real Time Clock, and SRAM for Static Random Access Memory.

[0075] The baseband circuit 320 receives a received signal that has been converted into a digital signal from the RF circuit 310. Through correlation processing and positioning calculations, it obtains satellite time information and positioning data. Using leap seconds stored in SRAM, it corrects the obtained satellite time information, i.e., the Z-count, and calculates the Coordinated Universal Time (UTC) as the time data. Then, the baseband circuit 320 outputs the positioning data and time data to the control unit 410.

[0076] The clock, which forms the basis of the local oscillation signal, is supplied from the TCXO330 to the RF circuit 310 via the baseband circuit 320.

[0077] The flash memory 340 stores a time difference database that corresponds to the location information determined by latitude and longitude and the time difference information of the location. When the GPS receiver 300 obtains location information in positioning mode, it obtains the time difference information (i.e., the time difference relative to UTC) based on the location information (latitude and longitude) and outputs it to the control unit 410.

[0078] [Control and Display Section]

[0079] The control display unit 400 includes a control unit (CPU) 410, a drive circuit 420 that drives pointers, etc., and a quartz oscillator 430.

[0080] The control unit 410 includes an RTC 411, a ROM 412, and a storage unit 413. It keeps track of time and outputs control signals to the GPS receiver 300 to control its operation.

[0081] RTC411 uses a reference signal output from quartz oscillator 430 to keep track of its internal time. ROM412 stores various programs executed by control unit 410. In this embodiment, the internal time kept track by RTC411 is in Coordinated Universal Time (UTC). If reception is successful in timing mode or positioning mode, control unit 410 updates RTC411 with UTC output from GPS receiver 300.

[0082] The storage unit 413 stores satellite time information, positioning information, and time difference information output from the GPS receiver 300. Therefore, the control unit 410 calculates the current time based on the UTC and time difference information, drives the drive mechanism 23 through the drive circuit 420, and indicates the calculated time through the hour hand 31, minute hand 32, and second hand 33.

[0083] [Power Supply Department]

[0084] The power supply unit 500 supplies power to the GPS receiver 300 and the control display unit 400, and includes a solar panel 25, a charging control circuit 510, a secondary battery 24, a first voltage converter 520, a second voltage converter 530, and a voltage detection circuit 540.

[0085] The charging control circuit 510 controls the charging of the secondary battery 24 by the power generated by the solar panel 25.

[0086] 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 receiver unit 300 via the second voltage conversion unit 530.

[0087] 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 control the receiving process by knowing the voltage of the secondary battery 24 detected by the voltage detection circuit 540.

[0088] [Dielectric Resonator Antenna]

[0089] Next, the dielectric resonator antenna (DRA) in electronic clock 1 will be explained. DRA is an abbreviation for Dielectric Resonator Antennas.

[0090] In watches that use high-frequency wireless communication such as GPS, when a glass cover with a high relative permittivity, such as sapphire crystal, is used, it functions as a dielectric resonator antenna (DRA), thereby improving antenna performance. The electric field of the dielectric resonator antenna is distributed in a ring shape and is enclosed inside a cylindrical dielectric resonator, with the linked magnetic field leaking out to the outside of the dielectric. Its resonant frequency varies depending on the resonant mode, but as an example, it can be represented in free space by the following mathematical equation (Equation 1), requiring a certain degree of glass thickness. Equation 1 represents the resonant frequency f0 of the cylindrical DRA. Furthermore, Dc is the diameter of the cylindrical dielectric resonator, and h is its thickness.

[0091] [Mathematical Expression 1]

[0092]

[0093]

[0094] In the resonance of DRA, the dielectric end is important. That is, as... Figure 8As shown, regarding the current distribution within the glass cover 15, since the outer periphery of the glass cover 15 is large, the glass edge and bezel 13 that fix the glass cover 15 have a significant impact. Therefore, while the metal housing 10 with the glass cover 15 shields radio waves, simply thickening the glass cover 15 does not actually improve the antenna characteristics. To improve the DRA performance, the metal housing 10 with the glass cover 15 needs to be constructed without shielding radio waves.

[0095] TE, which is the main resonant mode of DRA 011 In modal resonance, the electric field (electric field lines) is distributed in a ring and enclosed within the dielectric resonator, while the magnetic field (magnetic field lines) linking with it leaks out to the outside of the resonator. For example, if a conductor such as a microstrip line is brought close to the resonator, it can interact with the TE mode. 011 The mode is powered by magnetic field coupling. The magnetic field leaking from the resonator is the same as the magnetic field formed by a loop coil arranged along the electric field inside the resonator, surrounding the actual current flowing through it. The antenna operates in the same way as a loop antenna. There are no conductors in this resonant system, only dielectric loss and radiation loss. In particular, the loss of dielectrics at high frequencies is less than that of conductors, so less internal loss and higher radiation efficiency than a loop antenna can be expected.

[0096] However, if a metal of a certain size exists near the magnetic field of the DRA, the current that would impede the magnetic field generated by the resonance of the DRA will flow through the metal, and the radiation efficiency will decrease.

[0097] Therefore, in this embodiment, as Figure 2 As shown, a recess 131 is formed in the bezel 13 of the retaining glass cover 15 to reduce the amount of metal material present near the end of the glass cover 15, i.e., the bezel 13.

[0098] The bezel 13 is positioned on the inner circumferential surface below the recess 131, forming a facing surface 132 that opposes the side surface 153 of the glass cover 15 via a plastic gasket 17. Furthermore, the bezel 13 includes a support piece 133 protruding inward from below the facing surface 132. The support piece 133 is formed along the entire circumference of the facing surface 132 and abuts against the lower surface 152 of the glass cover 15 to support it.

[0099] The opposing surface 132 is a surface along the axial direction of the pointer axes 35-37, i.e., the first direction, and is a circumferential surface along the inner circumferential surface of the bezel 13. This opposing surface 132 is opposite to the side surface 153 of the glass cover 15, and the glass cover 15 is held in place by a plastic gasket 17. Thus, the glass cover 15 is mounted on the bezel 13, i.e., the housing 10.

[0100] 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 a surface located within a predetermined distance from the side surface 153 of the glass cover 15 and opposite to the side surface 153. A surface opposite to the side surface 153 refers to a surface that is arranged approximately parallel to the side surface 153. The condition of being located within a predetermined distance is a condition for determining a surface that is positioned at a distance that has a significant impact on the DRA. In this embodiment, the predetermined distance is set to 1 mm.

[0101] The dimension of the opposing surface 132 along the first direction, i.e., its height, is approximately 1.3 mm, which is about half the thickness of the glass cover 15, which is 2.6 to 2.8 mm. Therefore, in the first direction, the height H1 from the farthest end of the opposing surface 132 from the planar antenna 50, i.e., the upper end of the opposing surface 132, to the farthest part of the glass cover 15 from the planar antenna 50, is approximately 1.3 to 1.5 mm, which, as will be described later, is more than 1 / 60 of the wavelength shortened by the glass cover 15.

[0102] The recess 131 is configured to have a bottom surface 1311 extending from the inner circumferential surface of the annular bezel 13 toward the outer circumferential side and a side surface 1312 extending downward from the front surface of the bezel 13. The side surface 1312 is a circumferential surface along a first direction. The distance between the side surface 1312 and the side surface 153 is larger than the distance L, for example, about 2.8 mm.

[0103] Therefore, the side 1312 of the recess 131 of the bezel 13 is the opposite side 153, but since it is more than a specified size away from the side 153, it has little effect on the DRA.

[0104] A decorative plate 18 is disposed in the recess 131 of the bezel 13. The decorative plate 18 is formed in a ring shape when viewed from above, and is formed of a dielectric material such as glass or ceramic with a relative permittivity of 6 or higher. Figure 2 The thickness of the decorative plate 18 is, for example, 1.2 mm. Therefore, compared to the case where a metal bezel without a recess 131 is used, the DRA effect can be improved. That is, by providing a non-conductive decorative plate 18 in the recess 131 of the bezel 13, both design and antenna performance are taken into account.

[0105] As described above, by forming a recess 131 on the bezel 13 of the retaining glass cover 15 and arranging a decorative plate 18, which is a non-conductive component, in the recess 131, a DRA resonance effect based on the glass cover 15 can be obtained when receiving satellite signals through the planar antenna 50, thereby improving the receiving sensitivity of the planar antenna 50.

[0106] Next, refer to Figure 9The charts illustrate the results of simulations conducted to confirm the effectiveness of DRA.

[0107] Figure 9 This diagram illustrates the relationship between the thickness of the glass cover 15, made of sapphire glass with a relative permittivity of 10, and the antenna radiation efficiency when the planar antenna of the first embodiment receives radio waves transmitted from GPS satellites at a frequency of 1.575 GHz. Solid line 91 represents the simulation results when the thickness of the glass cover 15 is varied while the bezel 13 has a recess 131 and the height of the opposing surface 132 of the glass cover 15 is kept constant at 0.8 mm. Dashed line 92 represents the simulation results when the bezel 13 does not have a recess 131 and the height of the bezel 13 is varied according to the thickness of the glass cover 15; that is, the height of the opposing surface 132 of the bezel 13 is changed to approximately the same height as the outermost surface of the glass cover 15.

[0108] like Figure 9 As shown by the dashed line 92, even if the glass cover 15 is thickened, if the bezel 13 is correspondingly thickened, the antenna performance will decrease. On the other hand, as... Figure 9 As shown by solid line 91, with the height of the bezel 13 kept constant, antenna performance improves as the thickness of the glass cover 15 increases. Figure 9 In the results, when the difference between the thickness of the glass cover 15 and the thickness of the metal bezel 13 exceeds 1 mm, that is, when the height of the opposing surface 132 of the bezel 13 is 0.8 mm and the thickness of the glass cover 15 is 1.8 mm or more, and Figure 2 When the height dimension H1 becomes 1mm or more, the antenna performance improves. That is, it can be seen that in order to obtain the resonance effect of DRA, the upper surface 151 of the glass cover 15 needs to be separated from the upper end of the opposing surface 132 of the metal bezel 13, thereby increasing the height dimension H1.

[0109] Here, the wavelength shortening formula for the case where the relative permittivity of the medium is large becomes mathematical formula (2). Furthermore, λ0 is the free-space wavelength, and ε... r It is the relative permittivity of the dielectric.

[0110] [Mathematical Expression 2]

[0111]

[0112] The wavelength λ0 of a radio wave with a frequency of 1.575 GHz is approximately 190 mm, and the relative permittivity ε of the glass cover 15 is... rSince the value is 10, according to mathematical formula 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 opposing surface 132 to the farthest point of the glass cover 15 from the planar antenna 50 is 1.3 to 1.5 mm, therefore the height dimension H1 is more than 1 / 60 of the shortened wavelength by the glass cover 15.

[0113] Furthermore, since the upper surface 151 of the glass cover 15 is a plane, the distance from the planar antenna 50 in the first direction is the same at any position as long as it is the upper surface 151, and the upper surface 151 as a whole becomes the farthest part.

[0114] As described in the second and third embodiments below, when the glass cover is spherical, since the upper surface of the glass cover is curved upwards, the uppermost part of the glass cover is higher than the upper surface of the bezel, and the DRA effect can also be obtained in this case. In this case, it is not necessary to use a special bezel 13 with a recess 131, and the design freedom is increased.

[0115] As described earlier, a certain degree of glass thickness is required to fully utilize the DRA effect in the resonance of the glass cover 15. Figure 9 As shown by solid line 91 in the simulation results, antenna performance improves when the glass thickness exceeds 2 mm. Here, the wavelength λ shortened by the glass cover 15 is 60.1 mm, and the 2 mm glass thickness is 0.033 times (≈1 / 30) of the shortened wavelength λ. Therefore, the maximum thickness of the glass cover 15 is preferably more than 1 / 30 of the shortened wavelength.

[0116] In order to confirm the effect of the distance between the glass cover 15 and the planar antenna 50 on the reception characteristics, the change in antenna gain caused by the configuration position of the glass cover 15 was investigated in the electronic clock 1. Figure 10 This is a graph showing the results of simulating the change in antenna radiation efficiency when the distance H between the glass cover 15 and the planar antenna 50 in a first direction is varied. Furthermore, as... Figure 2 As shown, the distance H between the glass cover 15 and the planar antenna 50 is the distance between the upper surface of the planar antenna 50 (i.e., the upper surface of the first conductor element 52) ​​and the lower surface of the glass cover 15, which serves as the dielectric. The distance H needs to be set such that the hand positioned closest to the glass cover 15 does not contact the glass cover 15. In the general specifications of a clock with three hands (hour, minute, and second), the minimum value of the distance H is approximately 1.2 mm to 1.3 mm.

[0117] exist Figure 10In the example, the antenna radiation efficiency is shown with a distance H of 1.3 mm as the baseline, which is 0 dB. The results show the antenna radiation efficiency as the distance H increases.

[0118] like Figure 10 As shown, the smaller the distance H, that is, the closer the glass cover 15 is to the planar antenna 50, the better the antenna performance. This is because the electromagnetic coupling between the glass cover 15 and the planar antenna 50 becomes stronger.

[0119] The simulation results for the antenna radiation efficiency of the planar antenna 50 without the glass cover 15 are the same as those when the distance H is 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 glass cover 15. Here, the wavelength λ0 of the radio wave transmitted from the GPS satellite is approximately 190 mm. 190 mm ÷ 4.5 mm = approximately 42, therefore, the distance H can be set to 1 / 42 or less of the wavelength λ0.

[0120] [Effects of the First Embodiment]

[0121] According to the electronic clock 1 of this embodiment, a recess 131 is formed in the bezel 13. The height H1 from the upper end of the opposing surface 132 of the bezel 13 to the upper surface 151 of the glass cover 15 is at least 1 / 60 of the wavelength of the radio wave shortened by the glass cover 15, specifically at least 1 mm. Therefore, compared with the case where the thickness of the opposing surface 132 of the metal bezel 13 and the glass cover 15 are the same, 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 glass cover 15 is at least 1 / 30 of the wavelength of the radio wave shortened by the glass cover 15, specifically at least 2 mm. Therefore, the DRA effect can be further improved, and the antenna performance can be further improved.

[0122] The glass cover 15 is made of sapphire glass with a relative permittivity of about 9 to 11, which improves the DRA effect and further enhances the antenna performance.

[0123] In addition, since the decorative plate 18 disposed in the recess 131 is formed of a dielectric with a relative permittivity of 6 or higher, the effect of DRA can be improved, and both design and antenna performance can be taken into account.

[0124] The electronic watch 1 uses a planar antenna 50, which, compared with other antennas such as loop antennas and patch antennas described later, has a larger overlapping area with the glass cover 15 when viewed from above, thus improving the DRA effect compared with other antennas.

[0125] The dielectric substrate 51 of the planar antenna 50 also serves as a component of the movement 20, such as the recess 51C of the LED substrate 60, the date wheel pressure plate for pressing the date wheel 5, and the support substrate for the solar panel 25. Therefore, the freedom of movement design is increased, which is beneficial for the miniaturization and thinning of the electronic clock 1. On the other hand, the dielectric substrate 51 can also be a component dedicated to the planar antenna without serving other functions.

[0126] Since the first magnetic plate 26 also serves as the grounding component of the planar antenna 50 or the time wheel pressure plate, the freedom of movement design is further improved, which is conducive to the miniaturization and thinning of the electronic clock 1.

[0127] Since the LED substrate 60 is housed in the recess 51C of the dielectric substrate 51 and is positioned at approximately the same height as the dielectric substrate 51, the thickness of the movement 20 can be reduced, thereby enabling the electronic clock 1 to be made thinner.

[0128] By arranging the solar panel 25 on almost the entire front side of the planar antenna 50, the power generation area can be increased.

[0129] [Second Implementation]

[0130] Next, for Figure 11 The electronic clock 1B according to the second embodiment will be described. The main differences of the electronic clock 1B in the second embodiment are: a loop antenna 800 is used instead of a planar antenna 50; and a glass cover 15B made of hyperboloid glass is used instead of flat glass. In addition, the same reference numerals are used for structures that are the same as those in the first embodiment, and the description is omitted.

[0131] The loop antenna 800 is constructed by forming an antenna element 820 on a loop antenna substrate 810 formed of a dielectric using methods such as plating and silver paste printing. The dielectric material forming the antenna substrate 810 can be, for example, a resin material with a high dielectric constant of about 5 to 15, such as a material formed by mixing a ceramic dielectric material, such as titanium oxide, which can be used at high frequencies, with a synthetic resin.

[0132] When viewed from above the glass cover 15B, the antenna element 820 is a C-shaped ring element formed by cutting off a portion of the ring, which converts electromagnetic waves into current. The antenna element 820 is connected to the circuit board 70 via a power supply pin 840.

[0133] The loop antenna 800 is arranged along the outer periphery of the dial 2 and the solar panel 25. That is, the dial 2 and the solar panel 25 are arranged in the inner space of the loop antenna 800. The loop antenna 800 is covered by the dial ring 16B, which is arranged on the inner periphery of the bezel 13B.

[0134] The glass cover 15B is a hyperboloid glass with both its upper surface 151B and lower surface 152B curved surfaces. The thickness of the glass cover 15B is approximately 1.9 to 2.0 mm. The glass cover 15B is held in place by the bezel 13B. Furthermore, the bezel 13B of the electronic clock 1B differs from the bezel 13 of the electronic clock 1 in that it does not have a recess.

[0135] The height dimension of the side 153B of the glass cover 15B and the height dimension of the opposite surface 132B of the bezel 13B, which is separated from the side 153B by the plastic pad 17, are approximately the same.

[0136] In a first direction parallel to the axis of the pointer axes 35-37, the side of the glass cover 15B is defined as the upper part, and the side of the rear cover 14 is defined as the lower part. In this case, the center position of the upper surface 151B of the glass cover 15B when viewed from above, that is, the position overlapping with the pointer axes 35-37, becomes the uppermost part, and this uppermost part becomes the farthest part 155B that is furthest from the loop antenna 800 in the first direction. Figure 11 As shown, in the first direction, the height dimension H2 from the farthest end of the ring antenna 800 at the opposite surface 132B of the bezel 13B to the farthest part 155B is set to more than 1 / 60 of the wavelength shortened by the glass cover 15B, specifically more than 1 mm.

[0137] [Effects of the Second Embodiment]

[0138] The electronic clock 1B of the second embodiment has the same structure as the electronic clock 1 of the first embodiment, and thus can achieve the same effect.

[0139] That is, in the first direction, the farthest part 155B of the glass cover 15B is positioned above the opposing surface 132B of the bezel 13B, and its height dimension H2 is more than 1 / 60 of the wavelength shortened by the glass cover 15B, so the effect of DRA can be fully utilized to improve antenna performance.

[0140] The electronic clock 1B uses a glass cover 15B with hyperboloid glass, and no recess is formed in the bezel 13B, thus improving the versatility of the design.

[0141] Since the loop antenna 800 is arranged along the outer periphery of the dial 2, the antenna can be positioned on the front side of the movement 20, i.e., the glass cover 15 side, thus making it less susceptible to interference from watch components such as the stepper motor and improving reception performance.

[0142] [Third Implementation Method]

[0143] Next, for Figure 12The electronic clock 1C according to the third embodiment will be described. The main differences of the electronic clock 1C in the third embodiment are: the use of a patch antenna 900 and the use of curved glass as the glass cover 15C. In addition, the same reference numerals are used for structures that are the same as those in the first embodiment, and the description is omitted.

[0144] The patch antenna 900 is a surface-mounted patch antenna that has conductive antenna electrodes 920, ground electrodes, and power supply electrodes on a dielectric substrate 910.

[0145] The dielectric substrate 910 is made of square ceramic, for example, barium titanate with a relative permittivity of about 100 as the main raw material, formed by stamping and sintering.

[0146] Antenna electrode 920 is disposed on the front side of dielectric substrate 910. Ground electrode and power electrode are formed primarily by screen printing or other methods using a paste such as silver on the back side of 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 a ground plane. The power electrode is electromagnetically coupled to antenna electrode 920. Therefore, a power supply pin that does not require electrical connection between the power supply electrode and antenna electrode 920 is not required.

[0147] When the patch antenna 900 is square, one side of the antenna electrode 920 resonates at half the wavelength of the radio wave. Here, since the dielectric substrate 910 is formed of a high dielectric, the length of the antenna electrode 920 that resonates with the radio wave by utilizing the wavelength shortening effect can be shortened, and the patch antenna 900 can be miniaturized.

[0148] The glass cover 15C is composed of curved glass with an upper surface 151C that is curved and a lower surface 152C that is flat.

[0149] In the electronic clock 1C, in a first direction parallel to the axis of the pointer axes 35-37, the side of the glass cover 15C is defined as the upper part, and the side of the back cover 14 is defined as the lower part. In this case, the center position of the upper surface 151C of the glass cover 15C when viewed from above, that is, the position overlapping with the pointer axes 35-37, becomes the uppermost part, and this uppermost part becomes the farthest part 155C that is furthest from the patch antenna 900 in the first direction. Therefore, as Figure 12 As shown, in the first direction, the height dimension H3 from the farthest end of the patch antenna 900 on the opposite surface 132C of the bezel 13C to the farthest part 155C is set to more than 1 / 60 of the wavelength shortened by the glass cover 15C, specifically more than 1 mm.

[0150] To fully utilize the DRA effect generated by the resonance through the glass cover 15C, a glass thickness as the dielectric is required. Assuming the height dimension of the side surface 153C of the glass cover 15C is 'a' and the height dimension from the lower surface 152C to the farthest point 155C is 'b', in this embodiment, the height dimension a is 1.0 mm and the height dimension b is 2.4 mm. The height dimension of the opposing surface 132C of the bezel 13C is the same as the height dimension a of the side surface 153C of the glass cover 15C, and the height dimension H3 in the first direction from the upper end of the opposing surface 132C to the farthest point 155C is 1.4 mm. Therefore, the height dimension H3 is more than 1 / 60 of the shortened wavelength.

[0151] Figure 13 This is a graph showing the simulation results of antenna radiation efficiency based on the shape and thickness of the glass cover.

[0152] Figure 13 The graph shows the radiation efficiency calculated using a flat glass cover with a thickness of 1.0 mm and the glass cover 15C of the third embodiment, based on the antenna radiation efficiency of 0 dB when using a flat glass cover with a thickness of 2.4 mm. Figure 13 As shown, when using a flat glass dome with a thickness of 1.0 mm, the radiation efficiency is lower compared to a flat glass dome 15 with a thickness of 2.4 mm. However, with glass dome 15C, the radiation efficiency is approximately the same as that of a flat glass dome 15 with a thickness of 2.4 mm. That is, with glass dome 15C, even if the thickness of the side surfaces 153C at the ends is as thin as 1.0 mm, as long as the thickness of the central glass is 2.4 mm, antenna performance equivalent to that of a flat glass dome with a thickness of 2.4 mm can be obtained. Therefore, if a glass dome 15C made of curved glass is used, it is less susceptible to interference even when the glass dome 15C is held in place by a metal bezel 13C.

[0153] [Effects of the Third Embodiment]

[0154] The electronic clock 1C of the third embodiment has the same structure as the electronic clock 1 of the first embodiment, and thus can achieve the same effect.

[0155] That is, in the first direction, the farthest part 155C of the glass cover 15C is positioned above the opposing surface 132C of the bezel 13C, and its height dimension H3 is more than 1 / 60 of the wavelength shortened by the glass cover 15C, so the effect of DRA can be fully utilized to improve antenna performance.

[0156] The electronic clock 1C uses a curved glass cover 15C, and no recess is formed in the bezel 13C, thus improving the versatility of the design. In addition, because the electronic clock 1C uses curved glass, the ends of the glass cover 15C can be thinned, thereby making the electronic clock 1C appear thinner in design.

[0157] Because of its small size when viewed from above, the patch antenna 900 can be positioned so as not to overlap with the secondary battery 24, stepper motors 231-234, gear train, etc. This facilitates the miniaturization and thinning of the electronic clock 1C.

[0158] [Other Implementation Methods]

[0159] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be implemented within the scope of the spirit of the present invention.

[0160] The combination of the type of glass cover and the type of antenna is not limited to the combinations described in the embodiments. For example, a loop antenna 800 and a patch antenna 900 may be assembled in an electronic clock 1 with a glass cover 15 having flat glass. Alternatively, a planar antenna 50 and a patch antenna 900 may be assembled in an electronic clock 1B with a glass cover 15B having hyperboloid glass. Furthermore, a planar antenna 50 and a loop antenna 800 may be assembled in an electronic clock 1C with a glass cover 15C having curved glass.

[0161] As a cover component, it is not limited to sapphire glass; any dielectric material with a relative permittivity of 6 or higher and the properties required for a cover component of an electronic clock can be used.

[0162] Electronic clocks can also have a rotating bezel. In this case, even if the rotating bezel does not directly hold the glass cover 15, if the rotating bezel has a facing surface opposite the side 153 of the glass cover 15, and this facing surface is located within a predetermined distance from the side 153, it can be configured such that the height dimension from the end of the facing surface of the rotating bezel furthest from the antenna to the furthest part of the cover member furthest from the antenna is more than 1 / 60 of the wavelength shortened by the cover member.

[0163] Alternatively, recesses can be formed on the bezels 13B and 13C of the electronic clocks 1B and 1C in the same manner as on bezel 13, and decorative plates can be provided thereon.

[0164] In the first embodiment described above, the planar antenna 50 is configured to include a first magnetically resistant plate 26, but is not limited thereto. Alternatively, the second conductor element 53 may be formed in a plate shape with approximately the same area as the first conductor element 52, functioning as a grounding component for a plate-shaped inverted F-type antenna.

[0165] In the above embodiments, the antenna receives satellite signals transmitted from GPS satellites, but the signals received by the antenna are not limited to this. For example, it can also receive satellite signals transmitted from other Global Navigation Satellite Systems (GNSS) such as Galileo, GLONASS, and Beidou, Geostationary Satellite Navigation Augmentation Systems (SBAS), Quasi-Zenith Satellite Systems (RNSS) and other Regional Satellite Positioning Systems that can only be retrieved in specific regions.

[0166] Antennas are not limited to receiving satellite signals; they can also be antennas that receive other radio waves such as Bluetooth (registered trademark), BLE (Bluetooth Low Energy), Wi-Fi (registered trademark), NFC (Near Field Communication), and LPWA (Low Power Wide Area). In other words, the antennas assembled into electronic clocks 1, 1B, and 1C only need to be appropriate based on the type of signal received, the size of the clock, and its compatibility with other components.

[0167] [Summary of this disclosure]

[0168] The electronic clock disclosed herein is characterized by comprising: a conductive housing; a cover member mounted on the housing; a hand; a hand shaft on which the hand is mounted; and an antenna that receives predetermined radio waves and is configured to overlap with the cover member when viewed from a first direction parallel to the axis of the hand shaft, the cover member being made of a material that shortens the wavelength of the radio waves; the housing having an opposing surface opposite to a side surface of the cover member and positioned within a predetermined dimension from the side surface; and in the first direction, the height dimension from the farthest end of the opposing surface from the antenna to the farthest part of the cover member from the antenna is at least 1 / 60 of the wavelength shortened by the cover member.

[0169] According to the electronic clock disclosed herein, the cover component is made of a material that shortens the wavelength of radio waves. The height dimension from the end of the housing opposite to which the cover component is mounted, which is farthest from the antenna, to the farthest part of the cover component, which is farthest from the antenna, is more than 1 / 60 of the wavelength shortened by the cover component. That is, the cover component has a portion that protrudes upward in a first direction compared to the opposite surface of the housing. Therefore, the function of the dielectric resonator antenna using the cover component can be effectively utilized, and the radiation efficiency of the antenna can be improved.

[0170] In the electronic clock of this disclosure, preferably, the electronic clock has: a dial; a drive mechanism that drives the hands; and a base plate on which the drive mechanism is mounted, wherein the antenna has a plate-shaped conductor element having a through hole through which the hand shaft is inserted, and the antenna is disposed between the dial and the base plate when viewed from a second direction side perpendicular to the first direction.

[0171] According to the electronic clock disclosed herein, the antenna is disposed between the dial and the base plate, and also has a through hole through which the pointer shaft is inserted. Therefore, when viewed from above, it can ensure an area of ​​the same size as the dial. Thus, it can also increase the area overlapping with the cover component when viewed from above, and enhance the electromagnetic coupling with the cover component, thereby improving the antenna performance.

[0172] In the electronic clocks disclosed herein, it is preferred that the maximum thickness of the cover component is more than 1 / 30 of the wavelength after being shortened by the cover component.

[0173] According to the electronic clock disclosed herein, since the maximum thickness of the cover component is increased to more than 1 / 30 of the wavelength after the cover component is shortened, the effect of DRA can be improved, and the antenna performance can be improved.

[0174] In the electronic clocks disclosed herein, it is preferred that the cover component is made of a dielectric material with a relative permittivity of 6 or higher.

[0175] According to the electronic clock disclosed herein, the high relative permittivity of the cover component enhances the DRA effect and improves antenna performance.

[0176] In the electronic clocks disclosed herein, it is preferred that the housing has a recess that opens toward the opposing surface and the front of the housing, and a non-conductive decorative plate is disposed in the recess.

[0177] According to the electronic clock disclosed herein, since the housing has a recessed portion with an opening facing the opposing surface and the front of the housing, the height position of the uppermost part of the opposing surface can be lowered, ensuring the height dimension from the opposing surface to the farthest part of the cover member. Therefore, the influence of the housing, which is composed of conductive components, at the outer edge of the cover member can be reduced, improving the DRA effect and thus enhancing antenna performance.

[0178] In the electronic clocks disclosed herein, it is preferred that the decorative panel is made of a dielectric material with a relative permittivity of 6 or higher.

[0179] According to the present invention, the high relative permittivity of the decorative panel in the electronic clock can improve the receiving sensitivity of the antenna.

[0180] The electronic clock disclosed herein is characterized by comprising: a conductive housing; a cover member mounted on the housing; a hand; a hand shaft on which the hand is mounted; and an antenna that receives predetermined radio waves and is configured to overlap with the cover member when viewed from above in a first direction parallel to the axis of the hand shaft, the cover member being made of a material that shortens the wavelength of the radio waves; the housing comprising: an opposing surface opposing the side of the cover member and disposed at a position within a predetermined dimension from the side; and a recess opening toward the opposing surface and the front of the housing, wherein a non-conductive decorative plate is disposed in the recess; and 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.

[0181] According to the electronic clock disclosed herein, since a recessed portion with an opening facing the opposing surface and the front of the housing is formed in the housing, the height position of the uppermost part of the opposing surface can be reduced, thus ensuring the height dimension from the opposing surface to the farthest part of the cover member. Therefore, the influence of the housing composed of conductive components at the outer edge of the cover member can be reduced, improving the DRA effect and thus enhancing antenna performance.

Claims

1. An electronic clock, characterized in that, The electronic clock has the following features: A casing made of conductive metal; A cover component, which is mounted on the housing; pointer; A pointer axis, on which the pointer is mounted; as well as The antenna receives specified radio waves and is configured to overlap with the cover component when viewed from above in a first direction parallel to the axis of the pointer. The shielding component is made of a material that shortens the wavelength of the radio waves. The housing has opposing surfaces that face the side of the cover component and are positioned within a predetermined distance from the side. The housing has a recess that opens toward the opposing surface and the front of the housing. A non-conductive decorative panel is provided in the recess. In the first direction, the height dimension from the farthest end of the opposing surface from the antenna to the farthest part of the cover member from the antenna is more than 1 / 60 of the wavelength after being shortened by the cover member. In the first direction, the farthest part of the cover component is positioned above the end of the opposing surface.

2. The electronic clock according to claim 1, characterized in that, The electronic clock has the following features: dial; A drive mechanism that drives the pointer; as well as The base plate, on which the drive mechanism is mounted, The antenna has a plate-shaped conductor element with a through hole through which the pointer shaft is inserted. When viewed from a second direction perpendicular to the first direction, the antenna is positioned between the dial and the base plate.

3. The electronic clock according to claim 1 or 2, characterized in that, The maximum thickness of the cover component is more than 1 / 30 of the wavelength after it has been shortened by the cover component.

4. The electronic clock according to claim 1 or 2, characterized in that, The cover component is made of a dielectric material with a relative permittivity of 6 or higher.

5. The electronic clock according to claim 1, characterized in that, The decorative panel is made of a dielectric material with a relative permittivity of 6 or higher.

6. An electronic clock, characterized in that, The electronic clock has the following features: A casing made of conductive metal; A cover component, which is mounted on the housing; pointer; A pointer axis, on which the pointer is mounted; as well as The antenna receives specified radio waves and is configured to overlap with the cover component when viewed from above in a first direction parallel to the axis of the pointer. The shielding component is made of a material that shortens the wavelength of the radio waves. The housing has: an opposing surface opposite to the side of the cover member and positioned within a predetermined distance from the side; and a recess opening toward the opposing surface and the front of the housing. A non-conductive decorative panel is provided in the recess. In the first direction, the furthest part of the cover component that is furthest from the antenna is farther from the antenna than the furthest end of the opposing surface that is furthest from the antenna. The side of the cover component is farther away from the side of the recess than the opposing surface. The recess is closer to the front side of the housing than the opposing surface.

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