JP2019060672A - Electronic watch - Google Patents

Abstract

To enhance the reception characteristic of an electronic watch.SOLUTION: An electronic watch includes: a case; an antenna electrode 12 having a power supply position where a signal is supplied; and a tabular conductive member disposed inside the case. The antenna electrode 12 has a part between a position where the length from the power supply position is 1/2 times the length of the antenna electrode 12 and an antenna end, or between a first position where the length from the power supply position is 1/8 times the length of circumference of the antenna electrode 12 and a second position where the length from the power supply position is 3/8 times the length of circumference of the antenna electrode 12. The conductive member overlaps with the part in a plan view.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electronic watch that receives a signal from a satellite or the like.

  2. Description of the Related Art A portable electronic timepiece that receives time information included in a transmission signal from a satellite or the like that constitutes a GPS (Global Positioning System) and corrects the time has been put to practical use. The type and arrangement of antennas for receiving radio waves are determined so as to obtain the necessary reception sensitivity without impairing the function of the watch.

  Patent Document 1 discloses an electronic watch including an antenna body functioning as a loop antenna. It is disclosed in FIG. 2, FIG. 3, and FIG. 7 that the portion of the antenna pattern portion 40 c opposite to the feeding points 40 a and 40 b and the battery 27 overlap when viewed from the top. It is disclosed that the feeding point of the antenna pattern portion 42c and the battery 27 overlap.

Patent No. 5895700

  In order to generalize an electronic watch that receives radio waves, it is necessary to make the electronic watch smaller. Further, in order to miniaturize the electronic watch, it is necessary to miniaturize the antenna included in the electronic watch, but since the size of the antenna is closely related to the receiving characteristic, the receiving characteristic of the antenna may be deteriorated.

  The present invention has been made in consideration of the above circumstances, and its object is to provide an electronic watch that can be received using a smaller antenna.

(1) A case, an antenna electrode having a feeding position connected to a signal line and an antenna end, and a flat conductive member disposed inside the case, the antenna electrode being the feeding position Between the antenna end and a position where the length from the end is half the length of the antenna electrode, and the conductive member overlaps at least a part of the end side in plan view, Electronic clock.

(2) In (1), the conductive member overlaps the antenna end in a plan view.

(3) The electronic timepiece according to (1) or (2), further including a second antenna electrode having a feeding point to which a signal is fed and an antenna end, wherein the antenna electrode is shorter than the second antenna electrode.

(4) A case, a loop antenna, an antenna electrode having a feeding position to which a signal is supplied, and a flat conductive member disposed inside the case, the antenna electrode being the feeding position A first position where the length of the antenna electrode is 1⁄8 the length of the circumference of the antenna electrode, and a length 3/8 the length from the power supply position of the circumference of the antenna electrode An electronic watch, comprising: an intermediate portion between the two positions; and the conductive member overlaps the intermediate portion in plan view.

(5) The electronic timepiece according to (4), wherein the conductive member overlaps with a third position in which the length from the feeding point is 1⁄4 of the circumferential length of the antenna electrode in plan view.

(6) The electronic watch according to (4) or (5), wherein the antenna electrode is in the form of a coil of one turn.

(7) The electronic watch according to any one of (1) to (6), wherein the conductive member is at least one of a battery, a magnetic field proof plate, a solar cell, and a circuit board.

(8) The electronic watch according to any one of (1) to (7), further including a high dielectric member disposed between the antenna electrode and the conductive member.

(9) The electronic timepiece according to (8), wherein the high dielectric member is a dial or date dial.

(10) The electronic timepiece according to any one of (1) to (9), wherein no other conductive member is disposed between the conductive member and the antenna electrode.

(11) The electronic timepiece according to any one of (1) to (9), wherein the flat conductive member is closer to the antenna electrode than another flat conductive member facing the antenna electrode.

(12) The electronic timepiece according to any one of (1) to (11), wherein the conductive member is supplied with a ground potential.

(13) The electronic timepiece according to any one of (1) to (12), wherein the conductive member is a negative electrode of a battery, and an outer side of a center of the battery overlaps the antenna electrode.

  According to the invention, an electronic watch can be received using a smaller antenna.

It is a top view which shows an example of the satellite radio wristwatch concerning 1st Embodiment. It is sectional drawing in the II-II cutting plane line of the satellite radio wristwatch shown by FIG. It is a top view which shows an example of arrangement | positioning of an antenna electrode and a metal member. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic. It is a figure explaining the relationship between the capacitive coupling in an antenna, and a frequency characteristic. It is a figure explaining the current density in an antenna electrode. It is a top view which shows another example of an antenna electrode and a metal member. It is a top view which shows another example of a satellite radio watch. It is sectional drawing in the IX-IX cutting plane line of the satellite radio wristwatch shown by FIG. It is a top view which shows another example of a satellite radio watch. It is sectional drawing in the XI-XI cutting plane line of the satellite radio wristwatch shown by FIG. It is a top view which shows another example of a satellite radio watch. It is sectional drawing in the XIII-XIII cutting plane line of the satellite radio wristwatch shown by FIG. It is a sectional view showing another example of a satellite radio watch. It is a sectional view showing another example of a satellite radio watch. It is a sectional view showing another example of a satellite radio watch. It is a sectional view showing another example of a satellite radio watch. It is a top view which shows an example of the satellite radio wristwatch concerning 2nd Embodiment. It is a top view which shows an example of an antenna electrode. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic. It is a figure which shows the relationship between the position of a battery, and a frequency characteristic.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The satellite radio-controlled watch 1 according to the embodiment of the present invention will be described below. The satellite radio-controlled wristwatch 1 according to the present embodiment receives satellite radio waves including time information, and performs correction and positioning of the time kept by itself using the time information included in the received satellite radio waves.

First Embodiment
A configuration of a satellite radio-controlled wristwatch 1 using a dipole antenna or a monopole antenna will be described as a first embodiment of the present invention. FIG. 1 is a plan view showing an example of a satellite radio-controlled wristwatch 1 according to the first embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II of the satellite radio-controlled wristwatch 1 shown in FIG. As shown in these figures, the satellite radio-controlled watch 1 includes a windshield 31, a bezel 32 holding the windshield 31, a cylindrical barrel 38, and a back cover 39 provided under the barrel 38. . These constitute the outer shape of the satellite radio watch 1.

  The barrel 38 and the bezel 32 are sandwiched by the windshield 31 and the back cover 39. The body 38, the bezel 32 and the back cover 39 constitute an outer case of the satellite radio watch 1. In the following, the direction from the back cover 39 of the satellite radio watch 1 to the windshield 31 is referred to as upper, and the direction from the windshield 31 to the back cover 39 is referred to as lower.

  The barrel 38 is made of metal and has a vertically pierced hole. The bezel 32 is a ring-shaped member corresponding to the shape of the upper portion of the hole of the barrel 38. The bezel 32 is made of metal or ceramic. The bezel 32 is connected to the barrel 38 by being fitted to the top of the hole in the barrel 38. The back cover 39 is made of metal and has a flat surface corresponding to the shape of the lower part of the hole of the cylinder 38, and the back cover 39 is fitted in the lower part of the hole. The windshield 31 is, for example, sapphire glass. The windshield 31 has a planar shape corresponding to the shape of the upper portion of the opening of the bezel 32, and is fitted into the opening of the bezel 32.

  The satellite radio-controlled watch 1 includes the antenna electrodes 10a and 10b, ring-shaped dial ring 34, dial plate 51, hour hand 52a, minute hand 52b and second hand 52c, circuit board 47, battery 49, and the sun not shown in FIGS. Battery substrate 53 and magnetic plate 48 are included. These are disposed in the space enclosed by the windshield 31 and the exterior case. The material of the dial ring 34 is, for example, plastic. The battery 49 is, for example, a secondary battery and supplies a power supply potential and a ground potential. The upper surface of the battery 49 is an electrode for supplying a ground potential. Further, the satellite radio-controlled watch 1 includes a date dial (sun dial), a base plate, a drive mechanism, and the like, which are not shown in FIGS. 1 and 2, between the dial 51 and the back cover 39.

  The dial ring 34 is disposed between the dial 51 and the windshield 31. In the example of FIGS. 1 and 2, the antenna electrodes 10 a and 10 b extend along the periphery of the windshield 31 and the outer periphery of the dial 51, and are disposed on the back side of the windshield 31. The antenna electrodes 10a and 10b are arc-shaped electrodes. The antenna electrodes 10a and 10b have feeding points 12a and 12b at one end, the feeding points 12a and 12b are adjacent to each other, and the antenna electrodes 10a and 10b extend in different directions from the feeding points 12a and 12b. There is. The antenna electrodes 10a and 10b constitute a dipole antenna. Feed points 12a and 12b are connected to a balun circuit (not shown) through signal lines such as conductive pins, and the balun circuits are connected to a receiver circuit (not shown) disposed on circuit board 47 through signal lines. .

  The receiving circuit decodes the signals received by the antenna electrodes 10a and 10b, and outputs a bit string (received data) indicating the content of the satellite signal obtained as a result of the decoding. The receiving circuit includes a high frequency circuit (RF circuit) and a decoding circuit. The high frequency circuit operates at a high frequency, amplifies and detects an analog signal received by the antenna electrodes 10a and 10b, and converts it into a baseband signal. The decoding circuit decodes the baseband signal output from the high frequency circuit to generate a bit string indicating the content of data received from the GPS satellite, and outputs the bit string to a control circuit (not shown).

  The control circuit is a circuit that controls various circuits and mechanisms included in the satellite radio watch 1, and includes, for example, a microcontroller, a motor drive circuit, and an RTC (Real Time Clock). The control circuit acquires the time based on the received data and the clock output from the RTC, and drives the motor included in the drive mechanism in accordance with the acquired time. The drive mechanism is configured to include a step motor and a wheel train. When the train wheel transmits the rotation of the step motor, for example, one of the hour hand 52a, the minute hand 52b, and the second hand 52c is rotated. This will display the current time.

  In the example of FIG. 1 and FIG. 2, the antenna electrodes 10a and 10b are arc-shaped, and the length of each of the antenna electrodes 10a and 10b is described as an electrode length Ls. The antenna electrodes 10 a and 10 b may not necessarily be disposed on the back side of the windshield 31. For example, the antenna electrodes 10 a and 10 b may be disposed on the upper surface or the side surface of the dial ring 34. Further, in the case where the surface of the dial ring 34 has an inclined surface which is inclined with respect to the dial plate 51, the antenna electrodes 10a and 10b may be disposed on the inclined surface.

  Next, the arrangement of the conductive members disposed in the outer case and the antenna electrodes 10a and 10b will be described. Here, the conductive member disposed in the outer case has a large influence on the characteristics of the antenna because the distance between the conductive member and the antenna electrodes 10a and 10b is small, and the flat conductive member particularly affects the characteristics of the antenna. The flat conductive members are, for example, the battery 49, the magnetic shield 48, the ground electrode of the circuit board 47, and the solar cell substrate 53. A metal reflective film is provided on the lower surface of the solar cell substrate 53. The ground potential is supplied not only to the battery 49 and the ground electrode of the circuit board 47 but also to the magnetic shield 48 and the reflective film. In the following, the relationship between the flat plate-like metal member disposed in the outer case and the antenna electrodes 10a and 10b will be described in which the influence on the characteristics of the antenna is particularly large, but the flat plate-like other conductive members are also described. Applicable

  FIG. 3 is a plan view showing an example of the arrangement of the antenna electrodes 10a and 10b and the metal member. The feeding point 12 of FIG. 3 is a representation of the feeding points 12a and 12b of FIG. 1 collectively. The antenna electrode 10a has a portion S1 (end side) between its midpoint A1 and the end A2 on the side different from the feeding point 12a, and the antenna electrode 10b has its midpoint B1 and the feeding point 12b. A portion S2 (end side) is provided between the end B2 and the other end B2. The middle points A1 and B1 are positions where the length from the feeding point 12 is half of the electrode length Ls at the antenna electrodes 10a and 10b, respectively. When the portions S1 and S2 overlap the flat metal member (battery 49 in the example of FIG. 3) inside the outer case (only the cylinder 38 is shown in FIG. 3), the antenna can be miniaturized It is an area where you can get The flat metal member and at least a part of the portion S1 overlap in a plan view. In particular, the flat metal member and the end A2 of the antenna electrode 10a overlap in a plan view. The antenna electrodes 10a and 10b have a film shape or a plate shape. The battery 49 has a flat negative electrode on the upper side, and the negative electrode faces the antenna electrode 10a. The negative electrode is at ground potential. In the example of FIG. 3, another flat metal member to which the ground potential is not supplied is not disposed between the antenna electrode 10a and the battery 49. The battery 49 is the closest among the flat metal members facing the antenna electrode 10a.

  The flat metal member and the portion S2 may overlap in plan view. Further, the center of the battery 49 may not overlap with the antenna electrode 10a, and only the outer side of the center of the battery 49 may overlap with the antenna electrode 10a in plan view. The flat metal member may overlap only with the portion S1 of the antenna electrode 10a in plan view as in the example of FIG. 3, or may overlap with only the portions S1 and S2. Between the antenna electrode 10a which is a flat metal member and the battery 49, it is preferable that no other floating metal member is present. If it exists, it is preferable that the area where the other metal member and the antenna electrode 10a overlap in plan view is smaller than the area where the antenna electrode 10a and the battery 49 overlap.

  4A to 4C are diagrams showing the relationship between the position of the battery 49 and the frequency characteristics. FIG. 4A shows superimposed positions P1 to P4 where the battery 49 is disposed in plan view in measurement of frequency characteristics. At the time of measurement of the frequency characteristic, the battery 49 is disposed at any one of the superimposed positions P1 to P4. Also, the frequency characteristic is measured even when the battery 49 is not disposed. At the superimposed position P1, the end A2 of the antenna electrode 10a and the battery 49 overlap, and at the superimposed position P3, the middle point A1 of the antenna electrode 10a and the battery 49 overlap.

  FIG. 4B shows the resonance frequency of the antenna in the case where the battery 49 is not disposed and in each of the superimposed positions P1 to P4. When the battery 49 is not disposed, the resonance frequency is 1.32292 GHz. FIG. 4C shows the shift amount of the resonance frequency at the superimposed positions P1 to P4 in the case where the battery 49 is not disposed. The resonance frequency in the overlapping positions P1 to P3 is lower than that in the case where the battery 49 is not disposed, and in the overlapping position P4, the resonance frequency is higher than that in the case where the battery 49 is not disposed.

  As can be seen from FIGS. 4A to 4C, the resonance frequency can be lowered by overlapping a flat metal member such as the battery 49 with the portion S1 between the middle point A1 and the end A2 in plan view. In particular, when the flat metal member and the end A2 overlap, the resonance frequency can be lowered most. Here, assuming that the length between both ends of the dipole antenna is the antenna length La, in the case where the flat metal member and the portion S2 are superimposed when the resonance frequency is the same, the antenna length La is shorter than in the case where they are not superimposed. be able to. In the satellite radio-controlled wristwatch 1, since the antenna length La is smaller than the half wavelength λ / 2, the antenna can be miniaturized more easily.

  FIG. 5 is a diagram for explaining the relationship between capacitive coupling and frequency characteristics in the antenna. As can be understood from the description of FIG. 5A, when the antenna electrode 10a and the metal member (for example, the battery 49) overlap in plan view, stray capacitance is generated between the antenna electrode 10a and the metal member. Then, as shown in FIG. 5B, the antenna electrodes 10a and 10b and the stray capacitance are connected in parallel. As a result, the resonant frequency of the LCR circuit equivalent to the antenna is lowered, and the effective antenna length Le becomes longer than the actual antenna length La. Thereby, the actual antenna length La can be shortened while maintaining the resonance frequency.

  When the portions S1 and S2 overlap with the flat metal member, the influence on the sensitivity is also small. FIG. 6 is a diagram for explaining the current density in the antenna electrodes 10a and 10b. As shown in FIG. 6, the current density of the current flowing through the antenna electrodes 10a and 10b is maximum at the feed point 12 and is minimum around the ends A2 and B2. On the other hand, the region where the current density is high is easily affected by the metal member, and the sensitivity is largely reduced due to the overlapping of the metal members. Therefore, by overlapping the metal member outside the middle points A1 and B1 with a relatively low current density flowing through the antenna electrodes 10a and 10b in plan view, the influence of the metal member is reduced. The length of each of the antenna electrodes 10a and 10b is approximately La / 2, and the length between the middle points A1 and B1 and the feeding point 12 is approximately La / 4. By overlapping the antenna electrodes 10a and 10b and the metal member in plan view at a point where the influence on the sensitivity is small, the design freedom of the arrangement of the components in the case is increased.

  The antenna electrode 10a overlapping the flat metal member in plan view may be shorter than the antenna electrode 10b not overlapping the flat metal member in plan view. FIG. 7 is a plan view showing another example of the antenna electrodes 10a and 10b and the metal member. In the example of FIG. 7, the portion S1 between the middle point A1 and the end A2 of the antenna electrode 10a and the battery 49 overlap in a plan view. On the other hand, the antenna electrode 10b does not overlap with the flat metal member in plan view. In this example, the antenna electrode 10a overlapping the battery 49 is shorter than the antenna electrode 10b. Thus, even if the physical lengths of the antenna electrode 10a and the antenna electrode 10b are different, the electrical length can be equalized, so that the imbalance of the characteristics can be alleviated and the characteristic deterioration of the antenna can be suppressed.

  Further, both the portion S1 of the antenna electrode 10a and the portion S2 of the antenna electrode 10b may overlap with the flat metal member in plan view. FIG. 8 is a plan view showing another example of the satellite radio watch 1, and FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. In FIG. 8, the configuration below the dial 51 is described for ease of explanation. In the example of FIGS. 8 and 9, the magnetic shield 48 overlaps the step motor in plan view, and also overlaps the region SP2 near the end B2 of the antenna electrode 10b. Further, the battery 49 overlaps the region SP1 in the vicinity of the end A2 of the antenna electrode 10a. The magnetic plate 48 and the battery 49 are flat metal members. The area where the magnetic shield 48 and the antenna electrode 10b overlap in plan view is the area where the battery 49 and the antenna electrode 10a overlap, the distance d1 between the antenna electrode 10a and the upper surface of the battery 49, and the distance between the antenna electrode 10b and the magnetic shield 48 Depending on d2, it may be adjusted to obtain a desired antenna characteristic.

  FIG. 10 is a plan view showing another example of the satellite radio watch 1, and FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. In the example of FIG. 10, unlike the example of FIG. 8, the length (electrode length Lc) of the antenna electrode 10a and the length (electrode length Ld) of the antenna electrode 10b are different from each other. In the example of FIG. 10, the electrode lengths Lc and Ld are different so that the imbalance of the characteristics between the antenna electrode 10a and the antenna electrode 10b is alleviated. This length is the area where the magnetic shield 48 and the antenna electrode 10b overlap in plan view, the area where the battery 49 and the antenna electrode 10a overlap, the distance d3 between the antenna electrode 10a and the upper surface of the battery 49, the antenna electrode 10b and the magnetic shield It may be determined according to the distance d4 of 48 and the distance d4.

  12 is a plan view showing another example of the satellite radio watch 1, and FIG. 13 is a cross-sectional view taken along the line XIII-XIII in FIG. In the examples of FIGS. 12 and 13, the solar cell substrate 53 which is a flat metal member, and the antenna electrode 10a and the antenna electrode 10b overlap in a plan view. Also, the battery 49 is under the solar cell substrate 53, and in plan view, the region where the solar cell substrate 53 and the antenna electrode 10a overlap is overlapped with the battery 49. The distance d5 between the antenna electrode 10a and the solar cell substrate 53 and the distance d6 between the antenna electrode 10b and the solar cell substrate 53 are the same. On the other hand, the flat metal member closest to the antenna electrodes 10a and 10b to which the ground potential is supplied has a great effect on the antenna characteristics, and the metal characteristics of the metal member below the metal member on the antenna characteristics small. Therefore, it is easy to adjust the antenna characteristics by the solar cell substrate 53, and in the example of FIG. 12, the degree of freedom in the arrangement of the components can be increased as compared with the example described above.

  Also, a high dielectric member may be disposed between the antenna electrodes 10a and 10b and the flat metal member. The high dielectric member is, for example, a member such as ceramic, and the material of the high dielectric member may be, for example, alumina, silicon nitride (dielectric constant 8 to 10), zirconia (dielectric constant 28 to 33), or oxidation It may be a sintered body in which titanium (dielectric constant 60 to 100) is mixed. The material of the high dielectric member may be another ceramic material or resin material having a high dielectric constant.

  FIG. 14 is a cross-sectional view showing another example of the satellite radio watch 1. As shown in FIG. In the example of FIG. 14, the dial ring 34 is a high dielectric member, and the antenna electrodes 10 a and 10 b are disposed on the back surface of the windshield 31. The upper surface of the facing ring 34 is opposed to and adjacent to the lower surfaces of the antenna electrodes 10a and 10b. The high dielectric member shown in FIG. 14 not only achieves the wavelength shortening effect for the antenna electrodes 10a and 10b, but also increases the stray capacitance between the antenna electrode 10a and the metal member (here, the battery 49). The effect of downsizing can also be obtained.

  FIG. 15 is a cross-sectional view showing another example of the satellite radio watch 1. As shown in FIG. In the example of FIG. 15, the antenna electrodes 10a and 10b are below at least one of the dial ring 34 and the dial plate 51, and the high dielectric member 56 is disposed below the antenna electrodes 10a and 10b. A battery 49, which is a flat metal member, is disposed below the portion 56 and below the portion S1. The antenna electrodes 10 a and 10 b may be bonded to the lower surface of the dial 51 or dial ring 34. Also, the high dielectric member 56 may be made of a plastic containing a high dielectric, and may be, for example, a date dial.

  FIG. 16 is a cross-sectional view showing another example of the satellite radio watch 1. As shown in FIG. In the example of FIG. 16, unlike the example of FIG. 14, the ring-shaped high dielectric member 36 is provided on the upper side of the dial 51 along the inner peripheral surface of the bezel 32, and the antenna electrode 10 a is provided on the upper surface of the high dielectric member 36. , 10b are arranged. Furthermore, the antenna electrodes 10 a and 10 b and the high dielectric member 36 are covered by a dial ring 34.

  In addition, the present invention may be applied to a monopole antenna. FIG. 17 is a cross-sectional view showing another example of the satellite radio watch 1. As shown in FIG. In the example of FIG. 17, the antenna electrode 10a constitutes a monopole antenna. The antenna electrode 10a has a portion S1 between its midpoint A1 and an end A2 on the side different from the feeding point 12a. The flat metal member (the battery 49 in the example of FIG. 17) and the portion S1 overlap in a plan view. In particular, the flat metal member and the end A2 of the antenna electrode 10a overlap in a plan view. Even in the example of FIG. 17, the influence of the metal member on the sensitivity of the antenna can be reduced.

Second Embodiment
As the second embodiment of the present invention, the differences from the first embodiment will be mainly described with respect to the configuration of the satellite radio-controlled wristwatch 1 using a loop antenna.

  FIG. 18 is a plan view showing an example of the satellite radio-controlled wristwatch 1 according to the second embodiment. In the second embodiment, unlike the first embodiment, the antenna electrode 10 is in the form of a coil of one turn, and constitutes a loop antenna. The antenna electrode 10 is an arc-shaped electrode in which a part of the ring is cut in a plan view, and both ends thereof are adjacent to each other. The feeding points 12 a and 12 b are respectively present at the ends of the antenna electrode 10 and are adjacent to each other through the cut portion of the antenna electrode 10. The cross-sectional shape along the line AA in FIG. 18 is almost the same as that shown in FIG.

  FIG. 19 is a plan view showing an example of the antenna electrode 10. The feed point 12 of FIG. 19 collectively represents the feed points 12 a and 12 b in FIG. 18. In the present embodiment, the length from the feeding point 12 (one of the ends where the feeding point 12 is disposed) of the antenna electrode 10 is 1/8 times the circumferential length (loop antenna length Lb) of the antenna electrode 10 Has a portion S1 (intermediate portion) between the position F1 at which the distance F1 and the position F2 at which the length from one end is 3/8 the loop antenna length Lb, and the end at which the feeding point 12 is arranged Part between the position F3 where the length from the other is 1/8 times the loop antenna length Lb and the position F4 where the length from the other end is 3/8 times the loop antenna length Lb It has S2 (middle part). When viewed from one end of the antenna electrode 10a, the portion S2 has a position F3 where the length from one end thereof is 7/8 times the loop antenna length Lb, and the length from one end thereof is a loop There is a position F4 which is 5/8 times the antenna length Lb.

  In the second embodiment, a flat metal member such as the battery 49 overlaps the portion S1 in plan view. Furthermore, the flat metal member overlaps in plan view with the position F5 where the length from one end of the antenna electrode 10 is 1⁄4 of the loop antenna length Lb. Further, the center of the battery 49 does not overlap with the antenna electrode 10, and only the outer side of the center of the battery 49 overlaps the antenna electrode 10 in plan view. The flat metal member may further overlap with the portion S2, or may overlap with the position F6 where the length from the other end of the antenna electrode 10 is 1/4 times the loop antenna length Lb. Good. The flat metal member may overlap only with the portion S1 of the antenna electrode 10 in plan view as in the example of FIG. 19, or may overlap with only the portions S1 and S2. Also in the present embodiment, the configurations as shown in FIGS. 8 to 16 in the first embodiment can be applied.

  Assuming that the loop antenna does not overlap with the metal member, assuming that the facing point is located at a position separated by half from the feeding point 12, the first portion closer to the feeding point 12 than the facing point faces the feeding point 12 Each of the second portions close to the point has a current distribution corresponding to a dipole antenna. Therefore, the positions F1 to F4 correspond to the midpoints A1 and B1 in the first embodiment. The positions F5 and F6 correspond to the ends A2 and B2 in the first embodiment.

  20A to 20C are diagrams showing the relationship between the position of the battery 49 and the frequency characteristics. FIG. 20A shows superimposed positions PR1 to PR4 where the battery 49 is arranged in plan view in measurement of frequency characteristics. At the time of measurement of the frequency characteristic, battery 49 is arranged at any one of superimposed positions PR1 to PR4. Also, the frequency characteristic is measured even when the battery 49 is not disposed. At the overlapping position PR1, a position corresponding to the opposing point of the feeding point 12 in the antenna electrode 10 overlaps the battery 49. At superimposed positions PR2, PR3 and PR4, positions F2, F5 and F1 and battery 49 overlap in plan view. Here, the positions F4, F6, and F3 are symmetrical with respect to the positions F2, F5, and F1, respectively, with respect to the line connecting the feeding point 12 and the opposing point.

  FIG. 20B shows resonant frequencies of the antenna in the case where the battery 49 is not disposed and in the superimposed positions PR1 to PR4. When the battery 49 is not disposed, the resonance frequency is 1.92042 GHz. FIG. 20C shows the shift amount of the resonance frequency at the superimposed positions PR1 to PR4 as compared with the case where the battery 49 is not disposed. In the overlapping positions PR2 to PR4, the resonance frequency is lower than that in the case where the battery 49 is not disposed, and in the overlapping position PR1, the resonance frequency is higher than that in the case where the battery 49 is not disposed. If the battery 49 overlaps the antenna electrode 10 at the positions F4, F6, and F3, the same shift amount as when the battery 49 and the antenna electrode 10 overlap at the overlapping positions PR2, PR3, and PR4, respectively.

  As can be seen from FIGS. 20A, 20B, and 20C, the resonance frequency can be lowered by overlapping the portion S1 and the battery 49 which is a flat metal member in plan view. In particular, when the flat metal member and the position F5 overlap, the resonance frequency can be lowered most. Here, when the resonance frequency is the same, the loop antenna length Lb can be shortened. In other words, the antenna can be miniaturized more easily, and for example, the degree of freedom of the dielectric arrangement for obtaining the wavelength shortening effect is also improved. Further, similarly to the first embodiment, it is possible to reduce the decrease in sensitivity due to the proximity of the metal member.

  Although the case where the present invention is applied to the satellite radio watch 1 has been described above, the present invention can be applied to, for example, a portable small watch different from the watch.

  1 satellite radio-controlled watch, 10, 10a, 10b antenna electrode, 12, 12a, 12b feeding point, 31 windshield, 32 bezel, 34 look back ring, 36, 56 high dielectric member, 38 body, 39 back cover, 47 circuit board, DESCRIPTION OF SYMBOLS 48 Magnetic-resistant board, 49 batteries, 51 dials, 52a hour hand, 52b minute hand, 52c second hand, 53 solar cell substrate, A1, B1 middle point, A2, B2 end, d1, d2, d3, d4, d5, d6 distance, F1 , F2, F3, F4, F5, F6 position, S1, S2 part, SP1, SP2 area, La antenna length, Lb loop antenna length, Le effective antenna length, Ls, Lc, Ld electrode length, P1, P2, P3, P4, PR1, PR2, PR3, PR4 Superposing position.

Claims (13)

With the case,
An antenna electrode having a feeding position connected to the signal line and an antenna end;
A flat conductive member disposed inside the case;
Including
The antenna electrode has an end side between a position where the length from the feeding position is half of the length of the antenna electrode and the antenna end,
The conductive member overlaps at least a part of the end side in a plan view.
Electronic clock. In the electronic timepiece according to claim 2,
The conductive member overlaps the antenna end in plan view.
Electronic clock. The electronic timepiece according to claim 1 or 2
Further comprising a second antenna electrode having a feed point to which the signal is fed and an antenna end,
The antenna electrode is shorter than the second antenna electrode,
Electronic clock. With the case,
An antenna electrode which is a loop antenna and has a feeding position to which a signal is supplied;
A flat conductive member disposed inside the case;
Including
The antenna electrode has a first position at which the length from the feeding position is 1/8 times the circumferential length of the antenna electrode, and the length from the feeding position is the circumferential length of the antenna electrode Have a middle part between the second position which is 3/8 times
The conductive member overlaps the intermediate portion in plan view.
Electronic clock. In the electronic timepiece according to claim 4,
The conductive member overlaps a third position in which the length from the feeding point is 1⁄4 of the circumferential length of the antenna electrode in plan view.
Electronic clock. In the electronic timepiece according to claim 4 or 5,
The antenna electrode is a coil of one turn,
Electronic clock. The electronic timepiece according to any one of claims 1 to 6,
The conductive member is at least one of a battery, a magnetic plate, a solar cell, and a circuit board.
Electronic clock. The electronic timepiece according to any one of claims 1 to 7.
And a high dielectric member disposed between the antenna electrode and the conductive member.
Electronic clock. In the electronic timepiece according to claim 8,
The high dielectric member is a turnaround or a date wheel,
Electronic clock. The electronic timepiece according to any one of claims 1 to 9.
Another conductive member is not disposed between the conductive member and the antenna electrode,
Electronic clock. The electronic timepiece according to any one of claims 1 to 9.
The flat conductive member is closer to the antenna electrode than another flat conductive member facing the antenna electrode.
Electronic clock. The electronic timepiece according to any one of claims 1 to 11.
A ground potential is supplied to the conductive member.
Electronic clock. The electronic timepiece according to any one of claims 1 to 12.
The conductive member is a negative electrode of a battery,
Outside the center of the battery overlaps the antenna electrode,
Electronic clock.

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