JP2019045310A - Electronic watch - Google Patents

Abstract

To propose an electronic watch that can effectively improve reception sensitivity because its electrical inner peripheral length is 0.85λ≤L≤1.7λ for a wavelength λ of a radio wave.SOLUTION: An electronic watch comprises: an exterior case 2 that has an accommodation space part S; a timepiece display unit 3 that is accommodated in the accommodation space part S and displays timepiece internal time; and an antenna 4 that is accommodated in the accommodation space part S and receives a radio wave from the outside of the exterior case 2. An electrical inner peripheral length L with respect to an inner peripheral length opposite to the antenna 4 in a radial direction of the exterior case 2 is 0.85λ≤L≤1.7λ for a wavelength λ of the radio wave.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic watch.

  There is an electronic watch having a function of correcting the display time displayed by the watch display unit by receiving radio waves from the outside with an antenna in the outer case. In electronic timepieces, in particular electronic wristwatches, a metal case is used rather than a resin because high designability is required. It is known that when a metal outer case is used, the outer case encloses the antenna annularly, so that the reception sensitivity is lower than that of a single antenna.

  Therefore, an electronic watch has been proposed in which the reception sensitivity is improved by the wavelength shortening effect by arranging an annular dielectric auxiliary member in the housing space portion for housing the antenna of the outer case and the clock display unit (Patent Document 1).

JP, 2015-143664, A

  By the way, since the outer case surrounding the antenna in a ring shape is caused by the decrease in the reception sensitivity of the antenna, there is room for further improvement of the device for the outer case in order to improve the reception sensitivity.

  The present invention has been made in view of the above, and an object thereof is to propose an electronic watch capable of effectively improving the reception sensitivity.

  In order to solve the problems described above and achieve the purpose, the electronic watch according to the present embodiment includes an outer case having a housing space portion, and a clock display portion housed in the housing space portion and displaying a clock internal time. And an antenna which is accommodated in the accommodation space and receives radio waves from the outside of the outer case, and the electric inner circumferential length L with respect to the inner circumferential length facing the antenna in the radial direction of the outer case is With respect to the wavelength λ of the radio wave, 0.85 λ ≦ L ≦ 1.7 λ.

  The electronic timepiece according to the present invention has an effect that the reception sensitivity can be effectively improved since the electric inner circumferential length L is 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the radio wave. .

FIG. 1 is an entire configuration diagram of the electronic timepiece according to the first embodiment. FIG. 2 is a cross-sectional view of the electronic timepiece according to the first embodiment. FIG. 3 is a diagram showing the relationship between the reception sensitivity and the electrical inner circumferential length L. As shown in FIG. FIG. 4 is an entire configuration diagram of the electronic timepiece according to the second embodiment. FIG. 5 is a cross-sectional view of an essential part of the electronic timepiece according to the second embodiment. FIG. 6 is a view showing the relationship between the dielectric and the electrical inner circumferential length L. As shown in FIG. FIG. 7 is a view showing the relationship between the dielectric and the electrical inner circumferential length L. As shown in FIG. FIG. 8 is a diagram showing the relationship between the dielectric and the electrical inner circumferential length L. As shown in FIG. FIG. 9 is a diagram showing the relationship between the frequency shift amount and the total volume of the dielectric. FIG. 10 is a view showing the antenna mounting position of the electronic timepiece according to the modification. FIG. 11 is a view showing the antenna mounting position of the electronic timepiece according to the modification.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the following embodiments. In addition, constituent elements in the following embodiments include those that can be easily conceived by those skilled in the art or those that are substantially the same.

Embodiment 1
FIG. 1 is an entire configuration diagram of the electronic timepiece according to the first embodiment. FIG. 2 is a cross-sectional view of the electronic timepiece according to the first embodiment. 2 is an axial sectional view of the timepiece display portion 3 shown in FIG. 1 at the twelve o'clock position T12. The X direction in FIG. 1 (also in FIG. 4) is the front-rear direction of the electronic timepiece, X 1 is the front direction, and X 2 is the rear direction. Further, the Z direction in FIG. 2 (the same applies to FIGS. 5, 10, and 11) is the vertical direction of the electronic timepiece, Z1 is upward, and Z2 is downward.

  The electronic timepiece 1 in the embodiment corrects at least the internal time of the clock kept by the electronic timepiece 1 by receiving radio waves from the outside. The electronic timepiece 1 in the present embodiment uses GPS (GLOBAL POSITIONING SYSTEM) radio waves output from satellites as radio waves. GPS radio waves are radio waves including GPS time information, and there are currently two types of 1.5 GHz band (1575.42 MHz) and 1.2 GHz band (1227.60 MHz). As shown in FIG. 1 and FIG. 2, the electronic timepiece 1 has an exterior case 2, a timepiece display unit 3, an antenna 4, a windshield 5, a ring 6, a back cover 7, a control unit 8 and an actuator 9. , A wheel train 10, a battery 11, insulating members 12 and 13, a feed pin 14, a solar panel 15, and a belt 16. The electronic watch 1 in the present embodiment is described as a watch-type, and an analog electronic watch as the clock display unit 3 is an analog display type, but may be a clock-type or pocket-watch type, and the clock display unit 3 is a digital display type It may be

  The exterior case 2 is made of metal, for example, a conductive material such as titanium or a titanium alloy, and constitutes the outermost portion of the electronic timepiece 1. The exterior case 2 is formed with a housing space S, and has an annular portion 21 and a collar 22.

  The annular portion 21 constitutes the accommodation space portion S, and is annular in the present embodiment. As shown in FIG. 2, the annular portion 21 has openings at the top and bottom. By closing the upper opening with the windshield 5 and closing the lower opening with the back cover 7, the housing space S is made a closed space. The inner circumferential surface of the annular portion 21 constitutes the inner circumferential surface 2 a of the outer case 2 and has a projection 21 a. The protrusion 21 a is for receiving the windshield 5 and protrudes radially inward from the inner peripheral surface 2 a toward the center of the exterior case 2 to be formed annularly.

  The sleeves 22 connect the belts 16 and are two projecting forward from the forward end of the annular portion 21 and two projecting backward from the rear end. It is formed. In the electronic timepiece 1, one end of a belt 16 is connected between a pair of cans 22 and 22 in two on the forward side, and a pair of belts 22 is interposed between the pair of cans 22 and 22 in the rear side. The other end is connected, and the belt 16 is annularly connected to the outer case 2.

  Here, the exterior case 2 is formed such that the electrical inner circumferential length L is 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the radio wave. The electric inner circumferential length L in the present embodiment is the same as the inner circumferential length LI of the outer case 2 because the dielectrics 17 and 18 described later are not stored in the housing space S of the outer case 2. The inner circumferential length LI is a circumferential length of a portion facing the antenna 4 in the radial direction of the outer case 2. The inner circumferential length LI in the present embodiment is a circumferential length in a portion where the circumferential length is the smallest when viewed from the vertical direction, and is a circumferential length of the protrusion inner circumferential surface 2 b. The exterior case 2 has 161.75 mm ≦ inner circumferential length LI (= L) ≦ 323.50 mm if the GPS radio wave is in the 1.5 GHz band, and 207.58 mm ≦ inner circumference LI if the GPS wave is in the 1.2 GHz band. It is formed to be (= L) ≦ 415.16 mm. In other words, the outer case 2 has an inner diameter D, that is, a diameter of the protrusion inner circumferential surface 2b: 51.51 mm ≦ inner diameter D ≦ 103.03 mm for GPS radio waves in the 1.5 GHz band, and 1.2 GHz bands for GPS radio waves. And 66.11 mm ≦ inner diameter D ≦ 132.22 mm.

  The clock display unit 3 is housed in the housing space S and displays the clock internal time. The clock display unit 3 has a dial 31, a second hand 32, a minute hand 33, an hour hand 34, and a date plate 35. The dial 31 is formed in a disk shape, is fixed to the inner circumferential surface forming the housing space S of the outer case 2, and transmits at least light. The dial 31 has an index 31a, a small window 31b, and a through hole 31c through which the feed pin 14 passes. The index 31 a causes the user to recognize the display time by the hands 32 to 34 based on the relative positions of the second hand 32, the minute hand 33 and the hour hand 34. The indexes 31 a are formed at equal intervals in the circumferential direction with respect to the dial 31. The indexes 31a in the present embodiment are formed at equal intervals every 30 degrees. The small window 31 b is formed at a position facing the date dial 35 in the vertical direction of the dial 31, and penetrates the dial 31 in the vertical direction. The small window 31 b in the present embodiment has a rectangular shape, and is formed at the “3 o'clock” position on the dial 31. Each of the hands 32 to 34 is rotatably supported by a base (not shown), and coaxially rotates on the upper side of the dial 31, for example, at the center of the dial 31. The second hand 32 indicates "seconds" of the display time, the minute hand 33 indicates "minutes" of the display time, and the hour hand 34 indicates the display time according to the relative position with respect to the index 31a on the dial 31 Refers to "time". In each of the hands 32 to 34 in the present embodiment, the second hand 32 and the minute hand 33 have the same length from the center of the dial 31 in the radial direction, and the hour hand 34 is formed short. The date plate 35 is a rotary plate, is rotatably supported by a frame (not shown), and rotates on the lower side of the dial 31. A part of the date plate 35 is exposed to the upper side of the dial 31 by the small window 31 b. In the date plate 35, a plurality of characters of a series of character groups identifying a calendar are formed at equal intervals in the circumferential direction.

  The antenna 4 is accommodated in the accommodation space portion S and receives GPS radio waves from the outside of the exterior case 2. The antenna 4 is formed in a shape according to the frequency characteristic of the GPS radio wave to be received. The antenna 4 in the present embodiment is a dipole which is one of linear antennas, and is disposed between the dial 31 and the windshield 5. As shown in FIG. 2, the antenna 4 is attached to the surface of the windshield 5 that faces the dial 31, that is, the lower surface 5 a so as to face the protrusion 21 a in the radial direction. The antenna 4 has two feeding parts 41 and 41 and two antenna elements 42 and 42. Here, the antenna element 42 is made of a dielectric material such as copper, copper alloy, aluminum, aluminum alloy, silver, gold or the like.

  The feeding unit 41 outputs an antenna output signal based on the GPS radio wave received by the antenna element 42 to the control unit 8. The feeding portion 41 is formed at one end in the circumferential direction of the antenna element 42, and is integrally formed with the antenna element 42. The feed unit 41 is electrically connected to the main substrate 81 of the control unit 8 by the feed pin 14. The two feed parts 41, 41 are formed adjacent to each other in the circumferential direction. The two feeding parts 41, 41 are formed to face the 12 o'clock position T12 in the timepiece display 3 in the radial direction.

  The antenna element 42 is a portion for receiving GPS radio waves, and is formed in an arc shape along the circumferential direction. One of the antenna elements 42 is formed to extend along the clockwise direction of the circumferential direction from the feeding portion 41 on the clockwise side. The other antenna element 42 is formed extending from the feed section 41 on the counterclockwise side along the counterclockwise direction in the circumferential direction. Here, the length of the antenna element 42 is set according to the GPS radio wave to be received, and is set to 1/4 of the wavelength λ of the GPS radio wave to be received, that is, 1/4 λ.

  The windshield 5 closes the housing space portion S, and protects the clock display portion 3 and the antenna 4. The windshield 5 is fixed to the exterior case 2 so as to face the timepiece display unit 3 in the upper direction of the timepiece display unit 3. The windshield 5 transmits light because the user recognizes the clock display unit 3 and is formed of a material that transmits GPS radio waves, such as glass. The windshield 5 in the present embodiment is fixed to the exterior case 2 at the protrusion 21 a via the insulating member 12 such as an O-ring made of a non-conductive material, for example, rubber.

  The ring 6 is housed in the housing space portion S and is a decorative plate. The ring 6 is disposed between the dial 31 and the windshield 5 and has an annular shape. The ring 6 is attached to the upper surface of the dial 31, and the outer peripheral surface is in contact with the inner peripheral surface 2 a of the outer case 2. The ring 6 is formed with a through hole 6 a through which the feed pin 14 passes. The ring 6 suppresses an extreme step between the outer case 2 and the dial 31 in the vertical direction when the electronic timepiece 1 is viewed from the visible side, that is, the side where the timepiece display unit 3 can be viewed. The continuity from 2 to the dial 31 is improved.

  The back cover 7 closes the housing space S, and protects the control unit 8, the actuator 9, and the like. The back cover 7 is fixed to the exterior case 2 so as to face the timepiece display unit 3 in the downward direction of the timepiece display unit 3. The back cover 7 in the present embodiment is made of metal. The back cover 7 in the present embodiment is fixed to the outer case 2 through an insulating member 13 such as an O-ring made of a non-conductive material such as rubber. As a result, the back cover 7 is not electrically connected to the exterior case 2 and is in a non-connected state, so that the influence of the back cover 7 on the electrical inner circumferential length L can be suppressed.

  The control unit 8 is accommodated in the accommodation space portion S and controls the electronic timepiece 1, and is disposed below the timepiece display unit 3. The control unit 8 includes a main substrate 81, a sub substrate 82, a receiving circuit 83, a control circuit 84, a main substrate retainer 85, a sub substrate retainer 86, and conductive members 87 and 88. The control unit 8 only needs to be able to achieve the required functions, and the hardware configuration thereof is the same as or substantially the same as the hardware configuration of a known microcomputer.

  The main substrate 81 controls main functions of the electronic timepiece 1. The main substrate 81 in the present embodiment performs reception control by the antenna 4, drive control of the actuator 9, power control of the electronic timepiece 1, charge / discharge control of the battery 11, and the like. The main circuit board 81 has the receiving circuit 83 and the control circuit 84 mounted thereon, the battery 11 mounted thereon, and is electrically connected to the battery 11. The main substrate 81 is held by the main substrate holder 85. The main substrate 81 is electrically connected to the solar panel 15 via the conduction members 87 and 88.

  The sub substrate 82 controls an additional function of the electronic timepiece 1. The sub-substrate 82 in the present embodiment controls the solar panel 15 and the like. The sub substrate 82 is electrically connected to the main substrate 81 via the conduction member 87. The sub substrate 82 is electrically connected to the solar panel 15 via the conduction member 88.

  The reception circuit 83 performs reception control by the antenna 4. The receiving circuit 83 is electrically connected to the antenna 4 via the antenna 4 and the feed pin 14. The reception circuit 83 receives an alternating current which is an output based on the GPS radio wave received by the antenna 4. The receiving circuit 83 is electrically connected to the control circuit 84, and outputs an output based on GPS radio waves to the control circuit 84 as an antenna output signal. The receiving circuit 83 may also form a balun circuit (balance-unbalance conversion circuit).

  The control circuit 84 performs drive control of the actuator 9 and correction control of the internal clock time. The control circuit 84 outputs a drive pulse so that the second hand 32, the minute hand 33, and the hour hand 34 have a display time corresponding to the internal time of the clock based on the internal time of the clock kept by a timer (not shown). That is, the control unit 8 controls the actuator 9 to rotate the second hand 32, the minute hand 33, and the hour hand 34 in the clockwise direction, and causes the display time to correspond to the clock internal time. The control circuit 84 replaces the clock internal time with the GPS time information included in the GPS radio wave based on the antenna output signal, that is, corrects the clock internal time based on the GPS time information. Of the control circuit 84, a drive circuit for performing drive control of the actuator 9 may be mounted as a separate component on the sub-substrate 82 closer to the actuator 9 than the main substrate 81. The drive circuit is controlled in accordance with the signal from the control circuit 84.

  The main substrate retainer 85 fixes the main substrate 81 to the exterior case 2. The main substrate holder 85 is made of metal, that is, made of a conductive material, and has an earth spring 85a. The ground spring 85 a is formed to project from the lower side of the main substrate retainer 85 and is connected to the back cover 7. Here, since the back cover 7 is made of metal, the back cover 7 is electrically connected to the main board 81 via the main board retainer 85 and functions as the GND of the main board 81 and the sub board 82. In addition, since the back cover 7 is not electrically connected with the exterior case 2 or in a non-connected state, it is possible to suppress the influence of the back cover 7 on the electrical inner circumferential length L. Note that the ground spring 85 a may be in contact with the exterior case 2. Even in this case, since the electrical connection point between the control unit 8 and the exterior case 2 is one point of the ground spring 85a, the influence of the control unit 8 on the electrical inner circumferential length L is to be suppressed. it can.

  The sub substrate retainer 86 fixes the sub substrate 82 to the exterior case 2. The sub substrate holder 86 is made of metal, that is, made of a conductive material, and is disposed to face the main substrate 81 with the battery 11 interposed therebetween in the vertical direction.

  The actuator 9 is accommodated in the accommodation space S and rotates the hands 32 to 34 on the dial 31. The actuator 9 is, for example, an electromagnetic motor that is intermittently driven, and is connected to the respective needles 32 to 34 via the wheel train 10.

  The wheel train 10 is a decelerating mechanism housed in the housing space S and interposed between the actuator 9 and each of the hands 32 to 34. The second hand 32 is reduced every 60 seconds by decelerating the rotational speed of the actuator 9 One rotation is performed, the minute hand 33 is rotated once every 60 minutes, and the hour hand is rotated once every 12 hours.

  The battery 11 is housed in the housing space S and is a part of the power supply of the electronic timepiece 1. The battery 11 in the present embodiment is a secondary battery capable of charging and discharging, and supplies power to each device of the electronic timepiece 1 through the main substrate 81.

  The solar panel 15 is accommodated in the accommodation space portion S and is a part of the power supply of the electronic timepiece 1. The solar panel 15 generates electric power by the light incident on the accommodation space portion S from the outside of the electronic timepiece 1. The solar panel 15 is an assembly of photovoltaic elements, and the light receiving surface is disposed on the lower side of the dial 31 so as to face the dial 31. The solar panel 15 transmits the windshield 5 and the dial 31. It generates electricity by receiving the received light. The generated electric power is supplied to the main substrate 81 and the sub-substrate 82 through the conduction members 87 and 88 to supply electric power to each device of the electronic timepiece 1 or to charge the battery 11.

  The belt 16 is made of metal, for example, a conductive material such as titanium or a titanium alloy, or a nonconductive material such as a synthetic resin or a ceramic.

  Next, reception of radio waves by the electronic timepiece 1 in the present embodiment will be described. The controller 8 receives GPS radio waves when correcting the clock internal time. Specifically, an alternating current is generated in the antenna element 42 by the GPS radio wave output from the satellite. The alternating current is output from the feeding unit 41 to the receiving circuit 83 of the control unit 8. At this time, the current density of the antenna 4 is highest at the feeding portion 41 and lowest at the end of the antenna element 42 opposite to the feeding portion 41 side. The antenna 4 changes the intensity of radio wave radiation according to the current density. Therefore, the strength of the radio wave radiation of the antenna 4 is the highest at the feeding part 41 and the lowest at the end of the antenna element 42 opposite to the feeding part 41 side.

  Here, the relationship between the electrical inner circumferential length L of the outer case 2 and the reception sensitivity of the antenna 4 will be described. FIG. 3 is a diagram showing the relationship between the reception sensitivity and the electrical inner circumferential length L. As shown in FIG. The vertical axis in the figure is the reception sensitivity (C / N (dB)), and the horizontal axis is the electrical inner circumferential length L (λ times). As the reception sensitivity becomes positive, the reception sensitivity becomes higher, and as the electrical inner circumferential length L becomes positive, the electrical inner circumferential length L becomes longer. In order to explain the relationship between the electrical inner circumferential length L of the exterior case 2 and the reception sensitivity of the antenna 4, the exterior case 2 and the antenna 4 were reproduced on a simple substrate. Specifically, an arc-shaped dipole antenna was formed on a substrate, and a plurality of annular copper foils having different diameters were prepared outside the dipole antenna. Here, the copper foil constitutes the inner circumferential length LI of the outer case 2. That is, the circumferential length of the copper foil is the inner circumferential length LI, that is, the electrical inner circumferential length L in the present embodiment. The relationship between the reception sensitivity and the electrical inner circumferential length L when receiving radio waves in the 1.5 GHz band (1575.42 MHz) as GPS radio waves is PI shown in FIG. Here, ST shown in FIG. 3 is a reference reception sensitivity in the case where only a circular arc dipole antenna is formed on the substrate, and this reception sensitivity is assumed to be 0 dB. When the antenna 4 is enclosed by the exterior case 2, the decrease in reception sensitivity should be suppressed if the electrical inner circumferential length L (= LI) is 1 λ, that is, the same as or substantially the same as the wavelength of GPS radio waves. Can. As the reception sensitivity is in a range not lower than −1 dB with respect to the reference reception sensitivity, the occurrence of a practical problem as the electronic timepiece 1 can be suppressed.

  The electrical inner circumferential length L in the present embodiment is 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the GPS radio wave. If the electrical inner circumferential length L is less than 0.85 λ, the receiving sensitivity drops sharply when the electrical inner circumferential length L is 0.85 λ or more, and the receiving performance of the GPS radio wave as the antenna 4 is remarkable It is to decrease. On the other hand, the reason why the electrical inner circumferential length L is 1.75λ or less is that if the electrical inner circumferential length L exceeds 1.75λ, the reception sensitivity will be lower than the reference reception sensitivity, and the inner circumferential length As the LI increases, the outer diameter of the outer case 2 increases, and particularly when the electronic watch 1 is an electronic watch, the designability is degraded, that is, the reception sensitivity is effectively improved, and the designability is improved. It is because coexistence of suppression of a fall can not be aimed at. The electrical inner circumferential length L is preferably 0.85 λ ≦ L ≦ 1.3 λ with respect to the wavelength λ of the GPS radio wave. The reason why the electrical inner circumferential length L is 1.3 λ or less is that the receiving sensitivity is higher than −1 dB of the reference reception sensitivity even if the electrical inner circumferential length L is 1.3 λ or less, and the inner circumferential length LI (= L) becomes 247.38 mm or less, and the outer diameter of the exterior case 2 can be reduced while maintaining the effective improvement of the reception sensitivity, whereby the deterioration of the design can be further suppressed. Furthermore, the electrical inner circumferential length L is preferably 0.85 λ ≦ L ≦ 1.13 λ with respect to the wavelength λ of the GPS radio wave. The reason why the electrical inner circumferential length L is 1.13λ or less is that the receiving sensitivity is higher than −1 dB of the reference reception sensitivity even if the electrical inner circumferential length L is 1.13λ or less, and the inner circumferential length LI (= L) becomes 215.03 mm or less, and by further reducing the outer diameter of the exterior case 2 while maintaining the effective improvement of the reception sensitivity, it is possible to further suppress the deterioration of the design.

  As described above, in the electronic timepiece 1 according to the present embodiment, the electrical inner circumferential length L is set to 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the GPS radio wave. It is possible to suppress a decrease in reception sensitivity caused by accommodating the antenna 4 in the accommodation space S of the exterior case 2 with respect to the reference reception sensitivity). Therefore, in the electronic timepiece 1, even in the state where the antenna 4 is housed in the outer case 2, the reception sensitivity can be effectively improved.

  In the electronic timepiece 1 in the above embodiment, the inner circumferential length LI is set to the circumferential length of the inner circumferential surface 2b of the projection, but the present invention is not limited to this. It may be a circumference, and it may be a circumference at a portion where the circumference is the smallest. For example, in the case where the outer case 2 is formed with a projection for receiving the back cover 7, if the circumferential length of the inner peripheral surface of the projection for receiving the back cover 7 is the smallest, the back cover 7 is received. The outer case 2 is formed such that the circumferential length of the inner circumferential surface of the protrusion is 0.85 λ ≦ L ≦ 1.7 λ.

Second Embodiment
Next, the second embodiment will be described. FIG. 4 is an entire configuration diagram of the electronic timepiece according to the second embodiment. FIG. 5 is a cross-sectional view of an essential part of the electronic timepiece according to the second embodiment. The electronic timepiece 1 according to the first embodiment is, as shown in FIGS. 4 and 5, that the dielectrics 17 and 18 are disposed between the outer case 2 and the antenna 4 in the electronic timepiece 1 according to the first embodiment. Become. The electronic timepiece 1 according to the second embodiment is substantially the same in basic configuration and basic operation as the electronic timepiece 1 according to the first embodiment, and therefore, the components having the same reference numerals will be omitted or the description thereof will be simplified.

  The dielectrics 17 and 18 are made of a material having a dielectric constant ε higher than that of the outer case 2 and, for example, made of zirconia having a dielectric constant ε of about 30 to 40 or titanium oxide having a dielectric constant ε higher than zirconia. It is done. The dielectrics 17 and 18 are accommodated in the accommodation space S and are formed along the inner circumferential surface 2 a of the exterior case 2. The dielectrics 17 and 18 are opposed to the antenna 4 in the radial direction of the outer case 2 when viewed in the vertical direction. The dielectric 17 directly faces the antenna 4 when viewed in the radial direction, and is formed along the upper side of the dial 31 of the inner peripheral surface 2a. The dielectric 18 indirectly opposes the antenna 4 when viewed from the radial direction, and is formed along the lower side than the dial 31 of the inner peripheral surface 2 a. The dielectrics 17 and 18 in the present embodiment are both disposed in the housing space S in contact with the inner circumferential surface 2 a. The dielectric 17 has a protrusion 17 a formed along the protrusion 21 a. That is, the portion of the protrusion 21 a of the outer case 2 where the protrusion 17 a of the dielectric 17 is provided is not the protrusion inner circumferential surface 2 b of the protrusion 21 a but the inner circumferential surface 17 b of the protrusion 17 a is the antenna 4 Opposite. The dielectrics 17 and 18 are formed along a part of the entire circumference of the inner peripheral surface 2 a (including the projection inner peripheral surface 2 b) of the outer case 2. The dielectrics 17 and 18 in the present embodiment are formed in an arc shape so as to radially face at least a part of the feeding portion 41 and the antenna element 42 when viewed in the vertical direction. Here, the dielectrics 17 and 18 are formed symmetrically with respect to the feeding portion 41 in order to suppress a decrease in the reception sensitivity of the antenna 4.

  The dielectrics 17 and 18 are fixed to the outer case 2 by an adhesive or a biasing member. For example, in the case of an adhesive, first, an adhesive tape material having an adhesive is attached to the outer peripheral surface of the dielectrics 17 and 18, and then an adhesive tape material is attached to the inner peripheral surface 2a of the exterior case 2; Fix 17, 18 to the exterior case 2. In the case of an adhesive, first, a liquid adhesive, which is a liquid adhesive, is applied to at least one of the outer peripheral surfaces of the dielectrics 17 and 18 or the inner peripheral surface 2 of the outer case 2. By housing the dielectrics 17 and 18 in the portion S, the dielectrics 17 and 18 are fixed to the outer case 2 by a liquid adhesive. Here, since the adhesive is to be interposed between the dielectrics 17 and 18 and the exterior case 2, one having a high dielectric constant in order to increase the electrical inner circumferential length L of the dielectrics 17 and 18. preferable. In the case of the biasing member, a biasing member such as rubber is interposed between the dielectric 17 and the ring 6 and between the dielectric 18 and the main substrate retainer 85, respectively. Is urged radially outward, that is, the outer case 2 side, and the dielectric 18 is urged radially outward, ie, the outer case 2 side, with respect to the main substrate retainer 85. Although the case 2 and the dielectrics 17 and 18 are configured as separate members and the case of fixing them is described, the case 2 and the dielectrics 17 and 18 may be integrated.

Here, the relationship between the electrical inner circumferential length L of the outer case 2 and the dielectrics 17 and 18 will be described. 6 to 8 are diagrams showing the relationship between the dielectric and the electrical inner circumferential length L. FIG. The electrical inner circumferential length L is different from the inner circumferential length LI when the dielectrics 17 and 18 exist between the antenna 4 and the exterior case 2, and the dielectrics 17 and 18 are formed on the exterior case 2 having conductivity. It becomes long by contact (including almost contact). The electric inner circumferential length L of the outer case 2 is the inner circumferential length of a portion of the outer case 2 facing the antenna 4 in the radial direction, and the inner circumferential length of the dielectric 4 facing the antenna 4 in the radial direction. It is based on the dielectric constants of the dielectrics 17 and 18. Here, the effective dielectric constant in the dielectric 17, 18 with epsilon _e. The effective dielectric constant ε _e is based on the dielectric constant ε of the dielectrics 17 and 18, the width t in the radial direction of the dielectrics 17 and 18, and the distance d in the radial direction with respect to the exterior case 2 (ε _e = (ε , T, d)) increase as the dielectric constant ε of the dielectrics 17 and 18 increases. For example, as shown in FIG. 6, when the dielectric 17 is formed in an annular shape along the entire inner peripheral surface of the outer case 2, assuming that the inner peripheral length of the dielectric 17 is LA, L = LA × It becomes eε _e . Here, if the dielectric 17 is in contact with the inside surface of the case 2, the inner peripheral length LI is because the LA, the L = LI × √ε _e. In this case, for example, when the effective dielectric constant ε _e is 33, the electric inner circumferential length L is 5.74 times the inner circumferential length LI, and when the effective dielectric constant ε _e is 93, the electric inner radius L The circumferential length L is 9.65 times the inner circumferential length LI. Further, as shown in FIG. 7, when one dielectric 17 is formed in an arc shape along a part of the inner peripheral surface of the outer case 2, the inner peripheral length of the dielectric 17 is LA, and the outer case is of the inner peripheral surface of 2, the inner circumferential length of a portion where the dielectric 17 does not meet When LB, the _{L = LB + LA × √ε e} . Here, when the dielectric 17 is in contact with the inner peripheral surface of the outer case 2, the inner peripheral length LI = LA + LB. In this case, assuming that LA = 1/3 LI and LB = 2/3 LI, for example, when the effective dielectric constant ε _e is 33, the electrical inner circumferential length L is 2.58 times the inner circumferential length LI, which is effective. When the dielectric constant ε _e is 93, the electrical inner circumferential length L is 3.88 times the inner circumferential length LI. Further, as shown in FIG. 8, when two or more dielectrics 17 are formed in a circular arc along a part of the inner peripheral surface of the outer case 2, the inner peripheral length of the dielectric 17 is set to LA 1, LA 2, LA 3 Assuming that the inner circumferential lengths of portions where the dielectric 17 does not extend along the inner circumferential surface of the outer case 2 are LB1, LB2 and LB3, L = LB (= LB1 + LB2 + LB3) + LA (= LA1 + LA2 + LA3) × √ε _e It becomes. Here, when the dielectric 17 is in contact with the inner peripheral surface of the outer case 2, the inner peripheral length LI = LA + LB. In this case, assuming that LA = 1/2 LI and LB = 1/2 LI, for example, when the effective dielectric constant ε _e is 33, the electrical inner circumferential length L is 3.37 times the inner circumferential length LI, which is effective. When the dielectric constant ε _e is 93, the electrical inner circumferential length L is 5.32 times the inner circumferential length LI. That is, when the dielectrics 17 and 18 exist between the antenna 4 and the exterior case 2, the electrical perimeter L can be made several times longer than the internal perimeter LI of the exterior case 2, so Compared with the case where the dielectrics 17 and 18 do not exist between the lower case 2 and the outer case 2, the electric inner circumferential length L can be made longer without increasing the inner circumferential length LI of the outer case 2.

FIG. 9 is a diagram showing the relationship between the frequency shift amount and the total volume of the dielectric. The vertical axis in the figure is the frequency shift amount (MHz), and the horizontal axis is the total dielectric volume. The amount of frequency shift indicates the frequency shortening effect by the dielectrics 17 and 18, and means that the electrical inner circumferential length L becomes longer as it becomes positive. Here, assuming that the frequency in the case where the dielectric does not exist is f0, the frequency fa in the case where the dielectric exists is small. The amount of frequency shift is f0−fa, and the frequency decreases with the presence of the dielectric as plus, and λ increases as f decreases from f = v / λ. As the frequency shift amount becomes larger, the frequency shift amount becomes larger, and as the dielectric total volume becomes larger, the dielectric total volume becomes larger. In order to explain the relationship between the electrical inner circumferential length L of the outer case 2 and the dielectrics 17 and 18, the dielectrics 17 and 18 and the antenna 4 were reproduced with a simple model. Specifically, an arc-shaped dipole antenna model having a width of 1 mm and a thickness of 0.1 mm is formed in a three-dimensional space, and a width of 2 mm is opposed to the dipole antenna model in the axial direction of the dipole antenna model. A plurality of dielectric models were prepared with different arrangement and thickness for the dipole antenna model. The relationship between the amount of frequency shift and the electrical inner circumferential length L when receiving radio waves in the 1.5 GHz band (1575.42 MHz) as GPS radio waves is A to F shown in FIG. Here, A to C shown in the same figure, when the effective dielectric constant ε _e is 93, 33, 3 respectively, the ratio of the dielectric model to the entire circumference of the dipole antenna model (contact in the axial direction) By increasing it, the dielectric total volume is increased. Also, D to F shown in the same figure, when the effective dielectric constant ε _e is 93, 33, 3 respectively, the ratio of the dielectric model to the entire circumference of the dipole antenna model (contact in the axial direction) is constant The total volume of the dielectric is increased by increasing the thickness. As shown in A to F shown in the figure, even if the ratio occupied by the dielectric model or thickness is constant, the frequency shift amount increases and the electrical inner circumferential length L increases as the effective dielectric constant ε _e becomes higher. It will be done. Also, as shown in A to C in the same figure, even if the effective dielectric constant ε _e is the same and the thickness is constant, the frequency shift amount increases as the ratio occupied by the dielectric model increases, and The perimeter L will increase. Also, as shown by D to F in the figure, even if the effective dielectric constant ε _e is the same and the ratio occupied by the dielectric model is constant, the frequency shift amount increases as the thickness increases, and The perimeter L will increase. Also, as shown in A to F in the same figure, even if the effective dielectric constant _{e e} is the same, the increase in the ratio occupied by the dielectric model increases the frequency shift amount more than the thickness increases, and the electrical The inner circumferential length L will increase.

  As described above, in the electronic timepiece 1 according to the present embodiment, even when the dielectrics 17 and 18 exist between the antenna 4 and the exterior case 2, the electrical inner circumferential length L is compared to the wavelength λ of the GPS radio wave. Although it is set as 0.85 (lambda) <= L <= 1.7 (lambda), compared with the case where the dielectrics 17 and 18 do not exist between the antenna 4 and the exterior case 2, lengthening the internal peripheral length LI of the exterior case 2 Since it is possible to lengthen the electrical inner circumferential length L, in order to set the electrical inner circumferential length L to 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the GPS radio wave, It is possible to suppress the increase of the perimeter LI. Therefore, in the electronic timepiece 1, even in the state where the antenna 4 is housed in the outer case 2, the reception sensitivity can be effectively improved, and by reducing the outer diameter of the outer case 2, It is possible to suppress the decrease.

Further, in the electronic timepiece 1 according to the present embodiment, the dielectrics 17 and 18 are in contact with the outer case 2, thereby reducing the effective dielectric constant ε _e compared to the case where the dielectrics 17 and 18 are not in contact with the outer case 2. It can be suppressed. Therefore, in order to set the electric inner circumferential length L to 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the GPS radio wave, it is possible to further suppress the extension of the inner circumferential length LI of the exterior case 2 . Further, in the electronic timepiece 1 according to the present embodiment, by providing not only the dielectric 17 but also the dielectric 18, the length in the vertical direction of the entire dielectric, that is, the dielectrics 17 and 18 is regarded as one dielectric. The thickness in the case can be increased and the total dielectric volume can be increased. Therefore, in order to set the electric inner circumferential length L to 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the GPS radio wave, it is possible to further suppress the extension of the inner circumferential length LI of the exterior case 2 .

  Although the electronic timepiece 1 in the first and second embodiments has the antenna 4 attached to the windshield 5, the present invention is not limited to this, and it may be disposed in the housing space portion S. FIG. 10 is a view showing the antenna mounting position of the electronic timepiece according to the modification. FIG. 11 is a view showing the antenna mounting position of the electronic timepiece according to the modification. The antenna 4 may be attached to the ring 6 as shown in FIG. In this case, the ring 6 is attached to the surface facing the windshield 5 in the vertical direction, that is, the upper surface 6 b. Also, the antenna 4 may be attached to the inside of the ring 6 as shown in FIG. In this case, the ring 6 is formed to have an L-shaped cross section in the radial direction, and both ends in the tangential direction contact the inner peripheral surface of the exterior case 2 and the upper surface of the dial 31 respectively. A space is formed by the ring 6, the exterior case 2 and the dial 31. In the watch display unit 3, an antenna base 36 is formed between the dial 31 and the ring 6. The antenna base 36 is formed in an arc shape or a ring shape along the circumferential direction. The antenna 4 is attached to the surface of the antenna base 36 facing the ring 6 in the vertical direction, that is, the upper surface 36 a.

  Moreover, although the electronic timepiece 1 in the present Embodiment 1, 2 and the modification demonstrated the antenna 4 as a dipole antenna, it is not limited to this. The electronic timepiece 1 may be a loop antenna which is one of linear antennas. In this case, two feed parts 41 and 41 and one antenna element 42 are provided. The feeding portion 41 is formed to face the 12 o'clock position T12 in the timepiece display portion 3 in the radial direction. The antenna element 42 is formed in an annular shape along the circumferential direction from the one feed portion 41 to the other feed portion 41 opposed in the circumferential direction along the circumferential direction. The two feed parts 41, 41 are formed at positions facing the twelve o'clock position T12 in the timepiece display unit 3 in the radial direction. Here, the length of the antenna element 42 is set to the length of the wavelength λ of the GPS radio wave to be received. If the antenna 4 is a loop antenna, antenna characteristics are as if two dipole antennas are opposed in the radial direction. That is, in the antenna 4 in the modified example, an apparent feeding portion is present in a portion facing the two feeding portions 41 and 41 with the center of the outer case 2 therebetween.

  The antenna 4 may be a monopole antenna which is one of linear antennas, or may be a patch antenna, a chip antenna, an inverted F antenna, a slot antenna or the like. In addition, the antenna 4 may be attached to the space portion on the lower side of the dial 31 in the accommodation space portion S. For example, an antenna base may be formed on the main substrate 81 of the control unit 8 in a space below the dial 31 and the antenna 4 may be formed on the antenna base. Since the width in the radial direction of the ring 6 can be reduced as compared with the case where the antenna 4 is attached to the upper surface 6b of the ring 6 or the inside of the ring 6, the diameter of the solar panel 15 can be increased. The light receiving surface of the panel 15 can be enlarged. Further, by reducing the width of the ring 6 in the radial direction, the design can be improved.

  Further, the back cover 7 may be made of resin or ceramic. In this case, since the back cover 7 is made of a synthetic resin or ceramic which is a nonconductive material, the reception sensitivity of the antenna 4 can be further improved. In addition, the back cover 7 can be directly fixed to the outer case 2 without using the insulating member 13. In addition, even if the back cover 7 is made of metal, it is a central member made of a non-conductive material such as synthetic resin, ceramics, and glass for the purpose of improving the design and the reception sensitivity of the antenna 4; It may have an outer peripheral member formed of metal which is a conductive material surrounding the outer periphery of the central member. In this case, since the back cover 7 is electrically connected to the outer case 2 to be in a connected state, the electric inner circumferential length L is set in consideration of the influence exerted by the back cover 7.

  In the electronic timepiece 1 according to the first and second embodiments and the modification, the dielectrics 17 and 18 are formed along a part of the entire circumference of the inner peripheral surface 2 a of the exterior case 2, but along the whole circumference It may be formed. In the electronic timepiece 1 according to the first and second embodiments and the modification, the dielectrics 17 and 18 are formed along a part of the entire circumference of the inner peripheral surface 2 a of the outer case 2, but two or more It may be formed, i.e. distributed, along the points of. In this case, the dielectrics 17 and 18 are formed symmetrically with respect to the feeding portion 41 in order to suppress a decrease in the reception sensitivity of the antenna 4. In the electronic timepiece 1 according to the first and second embodiments and the modification, the dielectrics 17 and 18 are formed at positions facing the feeding portions 41 and 41 in the radial direction, but not facing the feeding portions 41 and 41 It may be formed at a position or a position not facing the antenna element 42.

DESCRIPTION OF SYMBOLS 1 electronic watch 2 exterior case 2 a inner circumferential surface 2 b protrusion inner circumferential surface 21 ring portion 21 a protrusion 22 ring 3 clock display portion 31 dial plate 32 second hand 33 minute hand 34 hour hand 35 sun plate 36 antenna base 4 antenna 41 feeding portion 42 antenna Element 5 windshield 6 ring 7 back cover 8 control section 9 actuator 10 wheel train 11 battery 12, 13 insulation member 14 feed pin 15 solar panel 16 belt 17, 18 dielectric S housing space T12 12 o'clock position

Claims (4)

An outer case having a housing space;
A clock display unit which is housed in the housing space portion and which displays a clock internal time;
An antenna which is accommodated in the accommodation space and which receives radio waves from the outside of the outer case;
Equipped with
An electrical inner circumferential length L related to an inner circumferential length facing the antenna in the radial direction of the outer case is 0.85 λ ≦ L ≦ 1.7 λ with respect to the wavelength λ of the radio wave.
An electronic watch characterized by In the electronic timepiece according to claim 1,
The electrical inner circumferential length L is the inner circumferential length,
Electronic clock. In the electronic timepiece according to claim 1,
A dielectric disposed between the outer case and the antenna;
The electrical inner circumferential length is an inner circumferential length in a portion facing the antenna in the radial direction of the outer case, an inner circumferential length of the dielectric facing the antenna in the radial direction, and the inner circumferential length of the dielectric Based on dielectric constant,
Electronic clock. In the electronic watch according to claim 3,
The dielectric is in contact with the outer case,
Electronic clock.

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