Electronic clock

Abstract

It suppresses malfunctions caused by static electricity. [Solution] The electronic clock comprises a substrate having an antenna, a metal plate-shaped member, and a case having a metal side wall facing the end face of the plate-shaped member, and housing the substrate and the plate-shaped member. The plate-shaped member is electrically connected to the side wall of the case, and a gap is provided between a part of the plate-shaped member and the side wall. The electronic clock may also include a conductive member interposed between the plate-shaped member and the side wall of the case to electrically connect the plate-shaped member and the side wall.

Description

Technical Field

[0001] The present invention relates to an electronic clock.

Background Art

[0002] Conventionally, a wristwatch capable of receiving radio waves including time information and the like by an antenna provided inside a metal case is known (for example, Patent Document 1). In a wristwatch, a metal dial may be used to enhance texture and design. When a metal dial is used in a wristwatch having an antenna, for example, a configuration may be adopted in which a gap is provided between the outer periphery of the metal dial and the metal case to secure a radio wave passing area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above configuration, since the plate-like member made of metal constituting the dial becomes electrically floating, the path for static electricity to flow from the plate-like member made of metal to the ground conductor becomes indefinite. Therefore, depending on the path of static electricity, a large current may flow through the electronic components on the circuit board, leading to problems such as malfunctions.

[0005] An object of the present invention is to suppress the occurrence of problems caused by static electricity.

Means for Solving the Problems

[0006] To solve the above problems, an electronic clock according to the present invention includes a substrate having an antenna, a plate-like member made of metal, A case having a metal side wall facing the end face of the plate-shaped member, and housing the substrate and the plate-shaped member, Equipped with, The plate-shaped member is electrically connected to the side wall of the case. A gap is provided between a part of the plate-like member and the side wall. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress the occurrence of malfunctions caused by static electricity. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the appearance of an electronic clock. [Figure 2] Figure 5 shows a cross-section of an electronic clock along line AA. [Figure 3] This is a diagram showing the circuit board and the first antenna. [Figure 4] This is a diagram showing a watch face. [Figure 5] This diagram shows the positional relationship between the internal protrusion of the main case, the dial, the conductive member, the insulating member, and the first antenna. [Figure 6] This figure shows a magnified view of a portion of the cross-section in Figure 2. [Figure 7] Figure 5 shows a cross-section of an electronic clock along line BB. [Figure 8] This figure shows other examples of dial designs. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. As shown in Figure 1, the electronic clock 1 comprises a case 2 in which a dial 7 (plate-shaped member) and hands 10 etc. are housed, and two bands 3 attached to the case 2. The electronic clock 1 is a wristwatch that is worn on the user's wrist by wrapping the bands 3 around the wrist. Hereinafter, the direction parallel to the plate surface 74 of the dial 7 (see Figure 2; the surface on which the hour markers etc. are drawn) will be defined as the +X direction at 3 o'clock and the +Y direction at 12 o'clock, and the direction perpendicular to the plate surface 74 of the dial 7 and from the back surface of the electronic clock 1 (the surface that contacts the wrist when worn) toward the front surface will be defined as the +Z direction (vertical direction). In addition, the surface of each member facing the +Z direction will be referred to as the "top surface," and the surface facing the -Z direction will be referred to as the "bottom surface." In Figures 2 to 8 below, some components of the electronic clock 1 may be omitted. Also, for the sake of explanation, the size and aspect ratio of each component may differ from the original.

[0010] As shown in Figure 2, the case 2 has a substantially cylindrical internal space and is open at the top, which is covered by a transparent disc-shaped crystal glass 12. The case 2 has a metal main case 21 (side wall) and a metal back cover 22. The main case 21 constitutes the side wall of the case 2 and is a substantially cylindrical member that is open at the top and bottom. The top of the main case 21 is covered by the crystal glass 12 as described above. An internal projection 211 (internal flange) protrudes from the inner wall surface 212 of the main case 21 toward the interior of the case 2. The internal projection 211 is continuous around the entire circumference of the inner wall surface 212. The upper and lower surfaces of the internal projection 211 are parallel to the XY plane. In this embodiment, the bezel surrounding the crystal glass 12 is made up of a part of the main case 21. However, it is not limited to this, and the bezel may be a separate member from the main case 21. In this case, the bezel may be made of metal. In this case, the bezel also constitutes part of the case 2. The case back 22 is a roughly circular metal member that seals the lower part of the main case 21. The case back 22 may be made of an insulating material, such as resin. The internal space formed by the case 2 and the crystal 12 houses the circuit board 4 (substrate), housing 5, frame member 6, dial 7, conductive spacer 8 (conductive member), insulating spacer 9 (insulating member), multiple hands 10 (in this embodiment, hour hand, minute hand, and second hand), and rotating shaft 11, etc.

[0011] The circuit board 4 is provided with various electronic components and electronic circuits for controlling the operation of each part of the electronic clock 1, including the pointer 10. A grounding conductor, which is at ground potential, is formed on the surface of the circuit board 4. The grounding conductor may extend across both the upper and lower surfaces of the circuit board 4 via through vias that penetrate the circuit board 4. As shown in Figure 3, a first antenna 14 (antenna) for wireless communication with external devices is provided near the periphery of the circuit board 4. Note that in Figure 3, the configuration of electronic components, electronic circuits, and grounding conductors other than the first antenna 14 is omitted. In this embodiment, the wireless communication method is Bluetooth®.

[0012] The first antenna 14 is designed to transmit and receive radio waves in the frequency band of 2.4 GHz to 2.48 GHz, which is used in Bluetooth. The wavelength of radio waves in the above frequency band in a vacuum is approximately 120 to 124 mm, and a quarter wavelength is approximately 30 to 31 mm. However, radio waves inside the case 2 are subject to a wavelength shortening effect depending on the relative permittivity of the material (mainly resin) through which the radio waves pass, which is housed in the case 2. If the wavelength of the radio waves in the above frequency band, taking the wavelength shortening effect into account, is denoted as λ, then in the electronic clock 1 of this embodiment, λ / 4 is approximately 15 mm. The first antenna 14 has an antenna pattern 141 and an antenna chip 142 connected to the antenna pattern 141. The antenna pattern 141 is a rod-shaped metal conductor provided on the surface of the circuit board 4. The antenna pattern 141 constitutes a grounded monopole antenna using the above-mentioned ground conductor. The antenna chip 142 is, for example, an electronic component for obtaining a wavelength shortening effect in the operating frequency band. By shortening the length of the antenna pattern 141 to less than λ / 4 (for example, to a length of about λ / 8) and providing an antenna chip 142 that provides a wavelength shortening effect, it is possible to transmit and receive radio waves in the Bluetooth frequency band. The antenna chip 142 may be omitted when wavelength shortening by the antenna chip 142 is not necessary. The antenna chip 142 is electrically connected to the ground conductor via an RF matching circuit or the like (not shown). Note that the shape of the antenna pattern 141 and the position of the first antenna 14 on the circuit board 4 are not limited to those exemplified in Figure 3 and can be changed as appropriate depending on the positional relationship with other components.

[0013] As shown in Figure 2, the housing 5 is located on the +Z side of the circuit board 4. The housing 5 is a housing component that houses the drive module (drive mechanism) and battery for rotating the pointer 10. The outer shape of the housing 5 is approximately cylindrical. The housing 5 is made of insulating resin. The lower surface of the housing 5 that is in contact with the circuit board 4 is provided with openings and notches for electrical connection between the drive module and the circuit board 4. The upper surface of the housing 5 is also provided with an opening for the rotation shaft 11 to pass through. The drive module inside the housing 5 rotates the rotation shaft 11, causing each pointer 10 attached to the rotation shaft 11 to rotate.

[0014] The frame member 6 holds the circuit board 4 and housing 5 so that they are integrated. In addition to the main frame shown below the circuit board 4 in Figure 2, the frame member 6 has side frames (not shown) that extend in the +Z direction from the end of the main frame and support the sides of the circuit board 4 and housing 5. The frame member 6 is made of a conductive metal. The frame member 6 has a leaf spring (not shown) that abuts against the back cover 22 and is electrically connected to the back cover 22 and the main case 21. The frame member 6 is also electrically connected to the ground conductor of the circuit board 4. Therefore, the frame member 6, back cover 22 and main case 21 also function as ground conductors.

[0015] The dial 7 is a disc-shaped member positioned on the +Z side of the housing 5. The surface 74 (top surface) of the dial 7 is provided with hour markers indicating the position of the hour, minute scales, etc. In this embodiment, the dial 7 is made of metal. Using a metal dial 7 enhances the texture and design of the electronic clock 1. A through hole 73 for passing the rotation shaft 11 is provided in the center of the dial 7. The end face 72 (side surface connecting the top and bottom surfaces) of the dial 7 faces the inner wall surface 212 of the main body case 21 without contacting the main body case 21. As shown in Figure 4, the dial 7 has a plurality of (four in this embodiment) protrusions 71a to 71d at its periphery that project in a direction parallel to the surface 74 (a direction parallel to the XY plane). Note that in Figure 4, only the outline of the dial 7 is shown, and the hour markers and minute scales provided on the surface 74 are omitted. Of the four protrusions 71, protrusions 71a and 71c are provided in positions and regions that are point-symmetric with respect to the center of the dial 7 (center of the through-hole 73) when viewed from the Z direction. Protrusions 71b and 71d are provided in positions and regions that are point-symmetric with respect to the center of the dial 7 when viewed from the Z direction. Hereinafter, any one of the protrusions 71a to 71d will be referred to as "protrusion 71". The shape of each protrusion 71 is obtained by removing a sector with a second radius r2, which is smaller than the first radius r1, from a sector with a first radius r1. The central angle of each sector may be, for example, within the range of 10 degrees to 45 degrees. Here, the first radius r1 is the length from the center of the dial 7 to the tip of the protrusion 71, and the second radius r2 is the length from the center of the dial 7 to the outline of the part of the dial 7 where the protrusion 71 is not provided. The amount of protrusion of the convex portion 71 (the difference between the first radius r1 and the second radius r2) is set to be within a range in which the tip of the convex portion 71 does not contact the inner wall surface 212 of the main case 21. As shown in Figure 5, each convex portion 71 overlaps with the inner protrusion portion 211 at least in part when viewed from the Z direction. The region R shown in Figure 4 represents the region of the convex portion 71 that overlaps with the inner protrusion portion 211. The dial 7 may be fixed on the housing 5 by restricting the position of each convex portion 71.For example, on the upper surface of the housing 5, corresponding to each convex portion 71, two protrusions may be provided at positions sandwiching both side ends of the convex portion 71, and the convex portion 71 and the protrusions may be engaged so that the side ends of each convex portion 71 are sandwiched between the two protrusions to regulate the position (movement) of the convex portion 71. Alternatively, the nameplate 7 may be fixed to the upper surface of the housing 5 by a double-sided tape.

[0016] As shown in FIGS. 2 and 6, a conductive spacer 8 is interposed between the convex portion 71a of the nameplate 7 and the inner protrusion 211 of the main body case 21. Specifically, the conductive spacer 8 is interposed between a portion of the convex portion 71a that overlaps the inner protrusion 211 when viewed from the Z direction (the portion corresponding to the region R) and the inner protrusion 211. In other words, the conductive spacer 8 is sandwiched between the upper surface of the convex portion 71a and the lower surface of the inner protrusion 211. However, as shown in FIG. 5, the conductive spacer 8 may extend to the outside of the portion where the convex portion 71a and the inner protrusion 211 overlap when viewed from the Z direction. In FIG. 5, dots are added to the conductive spacer 8 to make its extension range easier to see. In the present embodiment, the shape of the conductive spacer 8 is rectangular when viewed from the Z direction. The conductive spacer 8 electrically connects the nameplate 7 and the main body case 21 by contacting the nameplate 7 and the main body case 21. As described above, since the material of the upper surface of the housing 5 on which the nameplate 7 is placed is an insulating resin, the only conductive member in contact with the nameplate 7 is the conductive spacer 8. Therefore, when static electricity is generated on the metal nameplate 7, this static electricity flows to the main body case 21 and the back cover 22 via the conductive spacer 8. The conductive spacer 8 may be, for example, a copper piece with a gold plating on its surface. However, the conductive spacer 8 only needs to have conductivity, and its material is not limited to the above. In the present embodiment, the thickness d in the Z direction of the conductive spacer 8 shown in FIG. 6 is 0.2 mm. The conductive spacer 8 functions as a spacer that separates the nameplate 7 from the inner protrusion 211 in the -Z direction by the amount of its thickness d.

[0017] As shown in FIG. 2, an insulating spacer 9 is interposed between the convex portion 71c of the nameplate 7 and the inner protruding portion 211 of the main body case 21. In other words, the insulating spacer 9 is sandwiched between the upper surface of the convex portion 71c and the lower surface of the inner protruding portion 211. Further, as shown in FIG. 5, insulating spacers 9 are also arranged between the convex portion 71b and the inner protruding portion 211, and between the convex portion 71d and the inner protruding portion 211, respectively. That is, insulating spacers 9 are provided between the convex portions 71b to 71d, where the conductive spacers 8 are not provided, among the four convex portions 71a to 71d, and the inner protruding portion 211. As shown in FIG. 5, the insulating spacer 9 may extend to the outside of the overlapping portion of the convex portions 71b to 71d and the inner protruding portion 211 when viewed from the Z direction. Also, the shape of the insulating spacer 9 when viewed from the Z direction may be the same as the shape of the conductive spacer 8. In FIG. 5, dots are added to the insulating spacer 9 to make it easier to see the extending range of the insulating spacer 9. The material of the insulating spacer 9 is, for example, resin. However, the insulating spacer 9 only needs to have insulation, and its material is not limited to resin. The thickness d of the insulating spacer 9 in the Z direction is 0.2 mm. That is, the thickness of the insulating spacer 9 in the Z direction is the same as the thickness of the conductive spacer 8 in the Z direction. The insulating spacer 9 functions as a spacer that separates the nameplate 7 from the inner protruding portion 211 in the -Z direction by the amount of its thickness, similar to the conductive spacer 8. The position and arrangement area of the conductive spacer 8 provided on the convex portion 71a and the position and arrangement area of the insulating spacer 9 provided on the convex portion 71c are point-symmetrical with respect to the center of the nameplate 7 when viewed from the Z direction. Also, the position and arrangement area of the insulating spacer 9 provided on the convex portion 71b and the position and arrangement area of the insulating spacer 9 provided on the convex portion 71d are point-symmetrical with respect to the center of the nameplate 7 when viewed from the Z direction.

[0018] The dial 7 is positioned in the Z direction by abutting against the inward projection 211 from below in the +Z direction via the conductive spacer 8 and the insulating spacer 9. Therefore, the conductive spacer 8 and the insulating spacer 9 function as positioning members for the dial 7 in the Z direction. The position of the dial 7 in the Z direction can be adjusted by adjusting the thickness of the conductive spacer 8 and the insulating spacer 9.

[0019] As shown in Figure 5, when viewed from the Z direction, gaps 13a to 13d are provided between the portion of the dial 7 that does not overlap with the inner protrusion 211 (the portion where the convex portion 71 does not protrude) and the main body case 21 (inner protrusion 211). Each of the gaps 13a to 13d is provided between two adjacent convex portions 71 of the multiple convex portions 71a to 71d. Gap 13a is between convex portion 71a and convex portion 71b, gap 13b is between convex portion 71b and convex portion 71c, gap 13c is between convex portion 71c and convex portion 71d, and gap 13d is between convex portion 71d and convex portion 71a. In Figure 7, which shows a cross-section along the BB line in Figure 5, gaps 13b and 13d are shown. Radio waves received or transmitted by the first antenna 14 can pass through gaps 13a to 13d. Since the dial 7 and the main case 21 are made of metal, they shield the radio waves transmitted and received by the first antenna 14. However, by providing gaps 13a to 13d, it is possible to allow the radio waves transmitted and received by the first antenna 14 to pass through, thereby suppressing a decrease in the sensitivity of wireless communication in the electronic clock 1. Hereinafter, any one of the gaps 13a to 13d will be referred to as "gap 13".

[0020] As shown in Figure 5, the second antenna 15 is formed by the portion of the dial 7 and the main case 21 adjacent to the gap 13a, and the conductive spacer 8 that electrically connects these portions. The second antenna 15 is a slot antenna. In Figure 5, the area of ​​the gap 13a that functions as a slot for the slot antenna is shown by a thick dashed line. Specifically, the second antenna 15 includes a portion of the dial 7 adjacent to the gap 13a, a portion of the main case 21 adjacent to 13, a protrusion 71a (first protrusion), a protrusion 71b (second protrusion), and the conductive spacer 8 as its components. The ground conductor of the circuit board 4, the main case 21, and the back cover 22 also function as the ground for the second antenna 15. The distance between the protrusion 71a and the protrusion 71b (the length of the gap 13a that functions as a slot for the slot antenna) is determined to be a distance at which radio waves of a predetermined frequency can be received. Here, the predetermined frequency is the frequency of the radio waves transmitted or received by the first antenna 14, and in this embodiment, it is the frequency used in Bluetooth. The distance between the protrusions 71a and 71b may be a length that falls within a predetermined distance range centered on λ / 2, for example. Note that the range of the second antenna 15 shown by the dashed line in Figure 5 represents an approximate range in which the second antenna 15 functions, and does not limit the range of the second antenna 15. At least a part of the area shown by the dashed line in Figure 5 functions as the second antenna 15, and the remaining area may further function as the second antenna 15. The wireless communication function of the electronic clock 1 is realized by the first antenna 14 and the second antenna 15. Specifically, a portion of the radio waves transmitted from the first antenna 14 is received by the second antenna 15 and retransmitted (re-radiated) from the second antenna 15 to the outside of the electronic clock 1. The other portion of the radio waves transmitted from the first antenna 14 is transmitted (radiated) directly to the outside of the electronic clock 1 through the gap 13. Furthermore, a portion of the radio waves transmitted from the external device to the electronic clock 1 is received by the second antenna 15 and retransmitted from the second antenna 15. This retransmitted radio wave is received by the first antenna 14. Another portion of the radio waves transmitted from the external device to the electronic clock 1 is directly received by the first antenna 14 through the gap 13.

[0021] Point P1 shown in Figure 5 is the feed point of the first antenna 14 as viewed from the Z direction. The feed point P1 is the point where the high-frequency current related to the transmitted radio wave flows into the first antenna 14, and the point where the high-frequency current related to the received radio wave flows out from the first antenna 14. The feed point P1 is actually located on the circuit board 4. Point P2 shown in Figure 5 is a representative point (representative connection point P2) that represents the electrical connection position between the dial 7 and the main body case 21. In Figure 5, the representative connection point P2 is defined as the centroid of the area of ​​region R where the convex portion 71a and the inwardly protruding portion 211 overlap when viewed from the Z direction. However, the representative connection point P2 may be set at another position within region R. In order to enhance the radio wave relay function of the second antenna 15, it is preferable that the distance D between the feed point P1 and the representative connection point P2 is included in a predetermined distance range centered on 1 / 4 of the wavelength of the radio wave transmitted or received by the first antenna 14 (i.e., λ / 4 as described above). In other words, it is preferable to provide a conductive spacer 8 on one of the four protrusions 71a to 71d such that the distance between the power supply point P1 and the representative connection point P2 falls within the predetermined distance range described above, thereby electrically connecting the dial 7 and the main body case 21. Here, the predetermined distance range may be, for example, λ / 4 × 0.8 or more and λ / 4 × 1.2 or less, and more preferably λ / 4 × 0.9 or more and λ / 4 × 1.1 or less.

[0022] As described above, the electronic clock 1 according to this embodiment comprises a circuit board 4 having a first antenna 14, a metal dial 7, and a case 2. The case 2 has a metal main body case 21 (side wall) facing the end face 72 of the dial 7, and houses the circuit board 4 and the dial 7. The dial 7 is electrically connected to the main body case 21 of the case 2. A gap 13 is provided between a part of the dial 7 and the main body case 21. With this configuration, if static electricity is generated on the metal dial 7, this static electricity flows to the main body case 21 via the conductive spacer 8. By defining the transmission path of static electricity in this way, it is possible to prevent large currents from flowing due to static electricity to electronic components on the circuit board 4, for example. Therefore, the occurrence of malfunctions due to static electricity can be suppressed. In addition, by providing the gap 13, radio waves transmitted or received by the first antenna 14 can pass through the gap 13, so that radio waves can be transmitted and received by the first antenna 14 while using the metal dial 7. Furthermore, by electrically connecting the dial 7 and the main case 21, and by providing a gap 13 between the dial 7 and the main case 21, the portion of the dial 7 and the main case 21 adjacent to the gap 13 functions as a second antenna 15 (slot antenna). Therefore, compared to the conventional technology in which the dial is simply floating, the sensitivity (antenna gain) of wireless communication can be improved because the dial 7 functions as a second antenna 15.

[0023] Furthermore, the electronic clock 1 includes a conductive spacer 8 interposed between the dial 7 and the main case 21 of the case 2 to electrically connect the dial 7 and the main case 21. This allows the conductive spacer 8 to electrically connect the dial 7 and the main case 21 while also supporting the dial 7. Therefore, compared to the conventional configuration in which the dial 7 is free and floating, the dial 7 is less likely to shift position, improving the shock resistance of the electronic clock 1. In addition, the thickness of the conductive spacer 8 creates a gap 13 between the dial 7 and the main case 21, which allows radio waves to pass through more easily and improves the sensitivity of wireless communication.

[0024] Furthermore, the main case 21 has an internal projection 211 that protrudes toward the inside of the case 2, and a portion of the dial 7 overlaps with the internal projection 211 when viewed from the Z direction perpendicular to the surface 74 of the dial 7. The conductive spacer 8 is interposed between the portion of the dial 7 that overlaps with the internal projection 211 and the internal projection 211 in the Z direction. With this configuration, the position of the dial 7 in the Z direction can be adjusted by abutting the dial 7 toward the conductive spacer 8 in the Z direction.

[0025] Furthermore, the dial 7 has a plurality of protrusions 71 that project in a direction parallel to the plate surface 74 at its peripheral edge. Each of the plurality of protrusions 71 overlaps with the inner protrusion 211 in at least a portion when viewed from the Z direction. In addition, a conductive spacer 8 is interposed between some of the plurality of protrusions 71 and the inner protrusion 211, and an insulating spacer 9 is interposed between the plurality of protrusions 71 that do not have the conductive spacer 8 interposed between them and the inner protrusion 211. By providing the protrusions 71, a gap 13 can be created between the portion of the dial 7 that does not have the protrusions 71 and the main case 21. Furthermore, the dial 7 and the main case 21 can be electrically connected via the conductive spacer 8 provided on the protrusions 71. Furthermore, with the configuration that includes the protrusions 71, a gap 13a is created near the conductive spacer 8, so the portion of the dial 7 and the main body case 21 adjacent to the gap 13a, along with the conductive spacer 8, can function as a second antenna 15 (slot antenna). In addition, by interposing either the conductive spacer 8 or the insulating spacer 9 between each of the multiple protrusions 71 and the internal protrusion 211, the position of the dial 7 can be stabilized and the shock resistance of the electronic clock 1 can be improved.

[0026] Furthermore, the thickness d of the conductive spacer 8 in the Z direction is the same as the thickness of the insulating spacer 9 in the Z direction. This allows the dial 7 to be positioned in the Z direction using the conductive spacer 8 and the insulating spacer 9.

[0027] Furthermore, among the multiple protrusions 71, a gap 13a is provided between a protrusion 71a on which a conductive spacer 8 is provided and a protrusion 71b adjacent to the protrusion 71a. The electronic clock 1 includes the dial 7 and the portion of the inner protrusion 211 adjacent to the gap 13a, the conductive spacer 8, the protrusions 71a and 71b, and a second antenna 15 which is a slot antenna. As a result, the dial 7 can function as part of the second antenna 15, thereby improving the sensitivity of wireless communication compared to the conventional technology configuration in which the dial 7 is floating.

[0028] Furthermore, the distance between the two protrusions 71a and 71b is the distance at which the second antenna 15 can receive radio waves of a predetermined frequency. This makes it possible to receive and transmit desired radio waves, such as those used in Bluetooth, using the second antenna 15.

[0029] Furthermore, when viewed from the Z direction, a gap 13 is provided between the portion of the dial 7 that does not overlap with the inner protrusion 211 and the main case 21. This allows radio waves transmitted or received by the first antenna 14 to pass from one side of the dial 7 to the other in the Z direction. Thus, the sensitivity of wireless communication can be further improved.

[0030] Furthermore, the distance D between the feed point P1 of the first antenna 14 and the representative connection point P2, which is the electrical connection point between the dial 7 and the main body case 21, is determined to be a distance corresponding to the wavelength of the radio waves transmitted or received by the first antenna 14. In the above embodiment, the distance D between the feed point P1 and the representative connection point P2 is included in a predetermined distance range centered on 1 / 4 of the wavelength of the radio waves transmitted or received by the first antenna 14. This increases the antenna gain of the second antenna 15, thereby further improving the sensitivity of wireless communication.

[0031] It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. For example, the number of protrusions 71 is not limited to four. To support the dial 7, at least three protrusions 71 are sufficient, and five or more may be provided. Also, as shown in Figure 8, the dial 7 may have one recess 75 for forming a gap 13 as a slot for the second antenna 15 (slot antenna), and may have no protrusions 71. In this case, the entire outer circumference of the dial 7 excluding the recess 75 becomes the region R that overlaps with the inner protrusion 211. However, even in this case, it is preferable to arrange the conductive spacer 8 and the insulating spacer 9 at positions that are point-symmetric with respect to the center of the dial 7.

[0032] Alternatively, the conductive spacer 8 may be omitted, and a metal projection may be provided on the upper surface of some of the multiple protrusions 71 of the dial 7, and the dial 7 and the main case 21 may be electrically connected by bringing this projection into contact with the inner protrusion 211. An insulating spacer 9 can be interposed between the protrusions 71 that are not electrically connected to the inner protrusion 211 and the inner protrusion 211.

[0033] Furthermore, a gap 13 is not necessarily provided between the dial 7 and the main case 21 when viewed from the Z direction; for example, a gap 13 may be provided when viewed from a direction parallel to the XY plane.

[0034] Furthermore, the inner protrusion 211 of the main case 21 does not need to be connected around its entire circumference. It is sufficient that the inner protrusion 211 protrudes at least in a position that overlaps with the convex portion 71, and the inner protrusion 211 in positions that do not overlap with the convex portion 71 may be omitted.

[0035] Furthermore, conductive spacers 8 (or the aforementioned protrusions; the same applies hereafter in this paragraph) may be provided at two or more protrusions 71 to electrically connect them to the main body case 21. For example, in Figure 5, a conductive spacer 8 may be provided at the position of protrusion 71b instead of an insulating spacer 9. In this case, a closed circuit consisting of the dial 7, the main body case 21, and the two conductive spacers 8 is formed around the gap 13a. The second antenna 15 of the slot antenna can also be established with such a configuration. Alternatively, conductive spacers 8 may be provided at three or more protrusions 71, or at all of the protrusions 71, prioritizing electrostatic discharge resistance.

[0036] Furthermore, while the dial 7 is given as an example of a metal plate-like member, the invention is not limited to this. For example, a part of the dial 7 may be made of a metal plate-like member. For instance, the dial 7 may be a configuration in which a resin dial and a metal plate-like member are integrated, with the metal plate-like member exposed through an opening or notch provided in the resin dial. Alternatively, the metal plate-like member may be an anti-magnetic plate to suppress the effects of an external magnetic field.

[0037] Furthermore, although the above embodiment illustrates an analog electronic clock 1 that displays the time using a pointer 10, it is not limited to this. The electronic clock 1 may be a digital type that displays the time using a display device such as a liquid crystal display, or it may be a combination model that combines analog and digital methods.

[0038] Furthermore, the detailed configuration and operation of each component of the electronic clock 1 in the above embodiments can be appropriately modified without departing from the spirit of the present invention. Although embodiments of the present invention have been described, the scope of the present invention is not limited to the embodiments described above, but includes the scope of the invention as described in the claims and its equivalents. [Explanation of symbols]

[0039] 1…Electronic clock, 2…Case, 21…Main case (side wall), 211…Internal protrusion, 4…Circuit board (board), 7…Dial (plate-shaped member), 8…Conductive spacer (conductive member), 9…Insulating spacer (insulating member), 13, 13a~13d…Gap, 14…First antenna (antenna), 15…Second antenna, 71, 71a~71d…Protrusion

Claims

1. A substrate having an antenna, A metal plate-shaped member, A case having a metal side wall facing the end face of the plate-shaped member, and housing the substrate and the plate-shaped member, Equipped with, The plate-shaped member is electrically connected to the side wall of the case. A gap is provided between a part of the plate-like member and the side wall. Electronic clock.

2. The case includes a conductive member interposed between the plate-shaped member and the side wall of the case to electrically connect the plate-shaped member and the side wall. The electronic clock according to claim 1.

3. The side wall has an inward projection that protrudes toward the inside of the case, The plate-like member, when viewed from a vertical direction perpendicular to the plate surface of the plate-like member, has a portion that overlaps with the inwardly protruding portion. The conductive member is interposed between the portion of the plate-shaped member that overlaps with the inner protrusion and the inner protrusion in the vertical direction. The electronic clock according to claim 2.

4. The plate-like member has a plurality of protrusions at its peripheral edge that project in a direction parallel to the plate surface, Each of the aforementioned multiple protrusions overlaps with the inwardly protruding portion at least in part when viewed from the vertical direction. The conductive member is interposed between some of the multiple protrusions and the internally protruding portion. An insulating member is interposed between the convex portion of the plurality of protrusions that does not have the conductive member interposed therein and the inwardly protruding portion. The electronic clock according to claim 3.

5. The thickness of the conductive member in the vertical direction is the same as the thickness of the insulating member in the vertical direction. The electronic clock according to claim 4.

6. The gap is provided between the first protrusion on which the conductive member is provided and the second protrusion adjacent to the first protrusion. The slot antenna comprises the plate-shaped member, the portion of the inner protrusion adjacent to the gap, the conductive member, the first protrusion, and the second protrusion. The electronic clock according to claim 4.

7. The distance between the first protrusion and the second protrusion is the distance at which the slot antenna can receive radio waves of a predetermined frequency. The electronic clock according to claim 6.

8. When viewed from the vertical direction, the gap is provided between the portion of the plate-shaped member that does not overlap with the inwardly protruding portion and the side wall. The electronic clock according to claim 3.

9. The distance between the feed point of the antenna and the electrical connection point of the plate-shaped member and the side wall is determined to be a distance corresponding to the wavelength of the radio waves transmitted or received by the antenna. The electronic clock according to claim 1.

10. The distance between the power supply point and the connection position is within a predetermined distance range centered on one-quarter of the wavelength of the radio waves transmitted or received by the antenna. The electronic clock according to claim 9.

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