ELECTRONIC DEVICE AND TIMEPIECE

An electronic device includes: a date indicator that includes a letter part and a non-letter part different from the letter part, the non-letter part being a through hole; and a solar battery disposed below the date indicator.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to an electronic device and a timepiece.

Description of the Related Art

There is widely known an electronic device (e.g., a timepiece) including a solar panel that uses light to generate electricity. The solar panel generates electricity and charges a secondary battery, so that the timepiece is able to be used without replacement of batteries.

It is preferable that the solar panel be disposed at a visible side of the timepiece so that the solar panel certainly receives light and so that other components do not block light. A solar panel may be provided on the entire surface of the visible side of a timepiece to generate a greater amount of electric power.

However, unlike a dial as an example, a solar panel may not have an elaborated design on its surface. When a solar panel is disposed topmost and directly visible from outside, the external appearance of the timepiece may be deteriorated.

There is also a demand by users who love timepieces that the internal structure of a timepiece be visible. In particular, an analog timepiece that indicates time with hands includes therein a wheel mechanism that consists of gear wheels and so forth for rotating the hands. A timepiece that visibly exposes such a wheel mechanism as the external appearance will look excellent. However, main components of a wheel mechanism (e.g., gear wheels) are arranged around the central part of a timepiece. To make these components visible from outside, the timepiece needs to have a space in its central part that is not covered on its visible side.

For example, JP2002-350567A proposes disposing a ring-shaped solar panel at around the outer circumference of a timepiece and forming components that are disposed at the visible side of the solar panel with a material having a high level of optical transparency (e.g., transparent acrylic plate).

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, there is provided an electronic device including: a date indicator that includes a letter part and a non-letter part different from the letter part, the non-letter part being a through hole; and a solar battery disposed below the date indicator.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of a timepiece as an electronic device according to the present invention is described with reference toFIG.1toFIG.9.

The embodiment described below is provided with various limitations technically preferable for carrying out the present invention. However, the scope of the present invention is not limited to the embodiment below or illustrated examples.

A member such as a transparent acrylic plate, which is disclosed in the above-mentioned JP2002-350567A, absorbs light to some extent. When such a member covers the solar panel, the light reception efficiency of the solar panel decreases by the covered portion and the solar panel may fail to generate a sufficient amount of electric power.

The present disclosure allows an electronic device/timepiece to generate a sufficient amount of electric power with the solar panel and increases the flexibility in designing the electronic device/timepiece to provide a well-designed luxurious electronic device/timepiece.

FIG.1is a front view of a timepiece in this embodiment.FIG.2is an exploded perspective view of main components of the timepiece inFIG.1. InFIG.1and other figures, hands (minute hand, etc.) are not depicted.

In the following embodiment, the X direction corresponds to the direction of 9 o'clock and 3 o'clock, the Y direction corresponds to the direction of 12 o'clock and 6 o'clock, and the Z direction corresponds to the viewing direction from the visible side toward the invisible side. Hereinafter, the visible side may be referred to as “top side”, and the invisible side as “bottom side”. The X, Y directions and the Z direction (viewing direction) are shown inFIG.1.

The timepiece100in this embodiment includes a case (hereinafter called timepiece case1in this embodiment), as shown inFIG.1. The timepiece case1is made of metal (e.g., stainless, titanium), ceramic, or synthetic resin, for example. The material of the timepiece case1is not limited to these examples.

The timepiece case1in this embodiment has the shape of a hollow short column. To the opening11of the timepiece1at the front surface side (the visible side of the timepiece100, the side seen in the viewing direction Z inFIG.1andFIG.2), a windshield member2made of transparent glass, for example is attached. The back surface side of the timepiece100is covered by a not-illustrated back lid.

The timepiece case1has band attachment parts12at the ends of the timepiece case1in the top-bottom direction inFIG.1(the ends in the Y direction), namely at the ends corresponding to the 12 o'clock side and the 6 o'clock side of the analog timepiece. The band attachment parts12are for attaching a not-illustrated timepiece band.

The timepiece100has a not-illustrated operation receiver(s) (e.g., a crown, a push button), and the timepiece case1has a cut part13at a position corresponding to the operation receiver (e.g., on the lateral side of the timepiece case1).

Below the windshield member2(at the invisible side/back surface side of the windshield member2), a ring-shaped parting member3is disposed. The parting member3extends along the opening11of the timepiece case1. At the internal circumferential side of the parting member3, hour signs4are arranged at a predetermined interval. The hour signs4are pointed by not-illustrated hands (e.g., hour hand, minute hand) to indicate the time. The hour signs4are made of metal, such as stainless or titanium, for example. The material and the position of the hour signs4are not limited to these examples.

The timepiece case1houses a module5and so forth. The module5includes a main plate51, a not-illustrated motor, a not-illustrated antenna, a wheel mechanism52, and a board57(seeFIG.9A) that are appropriately dispersed on the front and the back of the main plate51(on the visible and invisible sides of the main plate51with respect to the timepiece). InFIG.2, the thick arrow indicates the viewing direction Z from the visible side toward the invisible side. The board57is mounted with not-illustrated circuits, terminals, and so forth.

In the timepiece100in this embodiment, a time indicator includes the hour signs4, the hands for pointing the hour signs4(e.g., not-illustrated hour hand and minute hand), and the module5including the motor and the wheel mechanism52for moving the hands. The time indicator of the timepiece100indicates the time in the analog method by pointing appropriate hour signs4with the hands moved via the wheel mechanism52.

The date indicator6is disposed above the module5(at the visible side of the timepiece). The date indicator6is rotated via the wheel mechanism52. On the date indicator6, the date indicator holder7is disposed.

In this embodiment, a solar battery is disposed at the invisible side of the date indicator6(i.e., below the date indicator6). The solar battery is disposed between the date indicator6and the module5. The solar battery in this embodiment is a ring-shaped solar panel8.

The timepiece100in this embodiment does not include a dial plate, for example. By omitting a dial plate, the timepiece100can be made thin with less plate members layered, namely less parts. Further, by omitting a dial plate, the timepiece1can avoid a decrease in generation efficiency, which may be caused by the material of the dial plate that absorbs light. Accordingly, the timepiece1can generate a sufficient amount of electric power with a smaller area of the effective electricity generation region (described later).

FIG.3shows an exploded perspective view that shows details of the module5, the date indicator6, the date indicator holder7, and the solar panel8.

As shown inFIG.3, the date indicator6includes a frame61and letter parts64. The frame61has a gear62that is formed along the circumference of the frame61and that engages with the gear wheel (gear wheel521inFIG.1to be described later) constituting the wheel mechanism52. The letter parts64are supported by the frame61via bridges63.

The date indicator6is made of metal, such as stainless or titanium. The non-letter parts of the date indicator6, which are different from the letter parts64, are through holes that pass through the date indicator6. Specifically, the non-letter parts are through holes that pass through the front and the back of the date indicator6. The non-letter parts are parts except (i) the letter parts64and (ii) parts necessary for supporting the letter parts64and for maintaining the shape of the date indicator6, such as the frame61and the bridge63.

The date indicator6is thus formed by making through holes on metal material (by lightening metal material). Such a date indicator6looks substantial and solid as compared with a date indicator made of transparent material on which letter parts are printed, and is able to give an air of luxuriousness to the external appearance of the timepiece.

The method of forming the date indicator6by making through holes on part of metal material except the frame61, the bridge63and the letter part64is not limited to a specific method.

To make the through holes, various methods are applicable: micromachining technology applied to micro electro mechanical systems (MEMS), etching, and laser processing, for example. The date indicator6may also be formed by punching out holes on a metal plate or by casting, for example.

The date indicator6in this embodiment includes, as the frame61, the first frame part61aand the second frame part61b. The second frame part61bis disposed inside the first frame part61a.

In this embodiment, the gear62is formed along the inner circumferential surface of the second frame part61b. Inside the second frame part61b(at the side closer to the rotation center), the gear62engages with the wheel that constitutes the wheel mechanism52.

The letter parts64of the date indicator6are parts that visually express the numbers from 1 to 31 as days in one month. Between one letter part64and the neighboring letter part64, a bridge63(first bridge part63a) is formed so as to partition one date from another. The bridge63(first bridge part63a) is formed across the first frame part61aand the second frame part61b.

FIG.4is an enlarged view in which part of the date indicator6in this embodiment (the letter part64corresponding to “16” and its surroundings) is enlarged.

As shown inFIG.4and so forth, each of the letter parts64in this embodiment is connected to the bridges63(second bridge parts63b) that cross the other bridges63(first bridge parts63a) and that extend along the circumferential direction of the frame61. Each of the letter parts64is supported by the frame61via the first bridge parts63aand the second bridge parts63b(i.e., the letter part64is supported between the first frame part61aand the second frame part61b).

The structure of the date indicator6is not limited to the one shown inFIG.4.

For example, the letter part64may be supported like a cantilever by the first frame part61aor the second frame part61bvia the bridge63, as shown inFIG.5. In the case, there may be only one frame61at the outside or inside of the letter part64. For example, inFIG.5, the frame61may consist of only the second frame part61b, which is inside the letter part64, and may not include the first frame part61aoutside the letter part64.

Conversely, the letter part64may be supported like a cantilever by the first frame part61aprovided outside the letter part64, and the second frame part61bmay be omitted. In such a case, the gear62is formed along the outer circumferential surface of the first frame part61a, and the gear62at the outside of the date indicator6engages with the gear wheel that constitutes the wheel mechanism52(the gear wheel521shown inFIG.1,FIG.3,FIG.7andFIG.8).

The first bridge part63a, which partitions one letter part64from another, is not essential. For example, when the letter part64is directly connected to the frame61via the bridge63(the second bridge part63b) that extends in the radial direction of the date indicator6as shown inFIG.5, the first bridge part63amay be omitted.

As described below, in this embodiment, the solar panel8is disposed below the date indicator6(at the invisible side of the date indicator6, below the date indicator6in the viewing direction Z). The date indicator6made of metal does not transmit light. When the frame61, the bridge63, and the letter parts64overlap with the solar panel8, the power generation efficiency decreases. It is therefore preferable that the date indicator6have as many (large) through holes as possible in order to minimize (narrow) the part constituting the frame61and the bridge63to the extent that the strength (shock resistance) of the date indicator6is retained. Regarding the letter parts64, the through holes are formed so as not to sacrifice the viewability of the letter parts64.

FIG.6is a front view of a configuration example of the solar panel in this embodiment.

The solar panel8is a solar battery that generates electricity using the received light. The electricity generated by the solar panel8through photovoltaic generation is stored in a not-illustrated secondary battery.

As shown inFIG.6, a ring-shaped panel (main body) of the solar panel8is divided into multiple cells81. The number of cells81into which the solar panel8is divided is not specifically limited. In this embodiment, the solar panel8is divided into five cells81(cell81ato cell81e).

The voltage generated by the solar panel8is stored in the not-illustrated secondary battery as a power source for the components constituting the timepiece100. However, a single cell (solar cell) generates a low voltage. To stably charge the secondary battery, in this embodiment, the solar panel8is divided into multiple cells81, and the cells81are connected in series, so that the solar panel can generate a higher voltage.

The greater the number of cells81connected in series is, the higher the voltage generated by the entire solar panel8is. It is preferable that the number of cells81constituting the solar panel8be determined according to the required voltage level (e.g., the voltage of the secondary battery that stores electricity generated by the solar panel8).

The solar panel8includes division lines82that divide the solar panel8into the cells81(cells81ato81e). In this embodiment, the division lines82extend in the radial direction of the ring-shaped solar panel8so that the cells81are substantially fan-shaped.

The parts corresponding to the division lines82are not used for generation of electricity. It is therefore preferable that the components disposed at the visible side of the solar panel8overlap with the division lines82to the extent possible. Accordingly, less areas are covered in the visible-side area of the effective electricity generation region, which is the region effectively used for electricity generation. This can restrain a decrease in generation efficiency.

In this embodiment, when the date indicator6is stationary, at least one of the bridges63of the date indicator6(the first bridge parts63aalong the radial direction of the date indicator6) overlaps with at least one of the division lines82of the solar panel8. More preferably, when the date indicator6is stationary, each of the division lines82of the solar panel8always overlaps with any of the bridges63of the date indicator6.

The shape of the division lines82corresponds to the shape of the bridges63(e.g., the first bridges63a). Thus, when the bridges63are positioned so as to correspond with the division lines82, the division lines82are hidden by the bridges63. This allows the timepiece1to look better. Since the effective electricity generation region is not covered by the bridges63, the timepiece100can restrain a decrease in electricity generation.

The solar panel8further incudes cell connectors83that connect the cells81. Each of the cell connectors83is disposed across the consecutive cells81. As described above, in this embodiment, the solar panel8is constituted of multiple division cells81and the cell connectors83that connect the cells81in series.

In one solar panel8that is constituted of multiple cells81connected in series, when output current values are different among the cells81, the output current value of the solar panel8is lowered according to the lowest current value among the cells81.

To increase the generation efficiency, it is preferable that the area of the effective electricity generation region of each cell81be as equal as possible.

In this embodiment, the intervals between the division lines are aligned so that the five cells81ato81ehave approximately the same area.

When a metal member that may affect electric generation (e.g., relatively large metal hour signs4or metal decorations, such as a not-illustrated logo) overlaps with the surface of the solar panel8, the optical transparency decreases in part of the effective electricity generation region of the cells81. As a result, the electric power generated by the cells81decreases, and the generation efficiency of the whole solar panel8decreases.

In such a case, it is preferable that the area of the substantial effective electricity generation region of each cell81be nearly equal to one another. For example, when a cell81has a low optical transparency in part of its effective electricity generation region, the cell81may have a greater area than the other cells81.

The parts corresponding to the cell connectors83are not used for generation of electricity, as with the parts corresponding to the division lines82. It is therefore preferable that the components disposed at the visible side of the solar panel8overlap with the cell connectors83to the extent possible.

Specifically, the cell connectors83are formed to overlap with the letter parts64of the date indicator6when the date indicator6is stationary, for example. The cell connectors83may be disposed under the hour signs4(the cell connectors83may overlap with the hour signs4). More preferably, when the date indicator6is stationary, each of the cell connectors83of the solar panel8always overlaps with any of the letter parts64of the date indicator6.

Preferably, the shapes of the cell connectors83are as close as possible to the shapes of overlapping members (letter parts64, hour signs4).

Accordingly, less areas are covered in the visible side of the effective electricity generation region. This can minimize a decrease in generation efficiency.

The inner circumferential part and the outer edge part of the ring-shaped solar panel8are not used for generating electricity (non-light-receiving region). As shown inFIG.1and so forth, in this embodiment, the frame61of the date indicator6(the first frame parts61a, the second frame parts61b) overlaps with the non-light-receiving region when viewed from the visible side.

According to such a configuration, the region of the solar panel8that corresponds to the through holes of the date indicator6is utilized as the light receiving region of the solar panel8. Further, the region of the date indicator6looks uniform and looks better. Further, the edges of the cells81of the solar panel8do not interfere with the edges of the through holes of the date indicator6, and the date indicator6can move smoothly. Further, the bridges63of the date indicator6are prevented from contacting the edges of the cells81of the solar panel8. Thus, the damage to the bridges63can be prevented.

The solar panel8further includes a date background region86at a part corresponding to the date indication position where the date indicator6indicates a date. The date background region86is colored so as to be highly distinguishable from the date indicator6.

For example, inFIG.1,FIG.3and so forth, the date background region86is part of the solar panel8that corresponds to the date and that is colored differently from the other part of the entire solar panel8. Specifically, inFIG.1, the date background region86is the part corresponding to the letter part “1” and colored white, whereas the other part of the solar panel8is shaded.

The date background region86is formed by directly coloring part of the surface of the solar panel8, for example. The coloring may be done by any method, such as printing or various techniques of vapor deposition.

The date background region86may also be formed by cutting out part of the solar panel8and fitting a plate or a film of a different color from the color of the solar panel8into the cut-out part or by attaching the plate/film to the cut-out part from the back surface side. The date background region86having a color clearly distinguishable from the date indicator6may also be formed by any other method.

The date background region86is formed at the position of 3 o'clock of the timepiece, for example. InFIG.6, the date background region86is formed in the effective electricity generation region of the cell81a.

When, for example, the date background region86is formed by fitting a plate or a film, the region corresponding to the date background region86cannot generate electricity. In consideration of the area of the date background region86, the area of the cell81amay be a little larger than the areas of the respective other cells81.

When the date background region86is not used for generation of electricity, the cell connector83may be provided at the position of the date background region86. By gathering as many regions not used for generation of electricity as possible at the same position, the effective electricity generation region can be maximized to the extent possible.

The solar panel8further includes contact parts84that are electrically connected to the board57(seeFIG.9A). The contact parts84may not be used as the effective electricity generation region. Therefore, preferably, the contact parts84are arranged inside or outside the ring-shaped main body so as not to affect the area of the effective electricity generation region of the solar panel8.

In this embodiment, three contact parts84are formed at three positions inside the ring-shaped main body of the solar panel8. As shown inFIG.3, one of the three contact parts84is in contact with the board57, which is disposed at the invisible side of the module5, via contact springs87.

The contact parts84may be provided outside the ring-shaped main body of the solar panel8. In the case, the contact parts84are disposed below the parting member3and favorably invisible from outside. However, in the assembled state, the contact springs87biases the solar panel8upward. To avoid the solar panel8and the date indicator6placed above the solar panel8from being pushed upward, a holder member for holding them is required on the contact part84(i.e., at around contact points at which the contact springs87are in contact with the contact part84). The holder member may be provided to the parting member3, for example.

When the contact parts84are provided inside the ring-shaped main body of the solar panel8as in this embodiment, the date indicator6is held down from the above by a date indicator holder, as described later. The date indicator holder can hold the pushing of the contact springs87without any additional members.

In this embodiment, the contact parts84also function as a rotation preventer that prevents the solar panel8from rotating in the circumferential direction.

When the ring-shaped main body of the solar panel8has no projections or recesses on its circumferential surface, the solar panel8may rotate in the circumferential direction by the rotation of the date indicator6, the vibration applied to the timepiece100, or other effects. To prevent the solar panel from rotating, the solar panel8may have to be screwed through screw holes at the sacrifice of the effective electricity generation region, for example.

In this embodiment, the contact parts84are formed at the inside or outside of the ring-shaped main body. These contact parts84can be used for preventing the solar panel8from rotating in the circumferential direction.

Specifically, as shown inFIG.3andFIG.7, recess parts55are formed in the module5(e.g., in the visible-side surface of the main plate51) at positions corresponding to the contact parts84. The shape of the recess parts55corresponds to the shape of the contact parts84so that the contact parts84fit in the respective recess parts55in the assembled state. With such a configuration, the solar panel8is prevented from rotating in the circumferential direction, and the position of the solar panel8with respect to the circumferential direction is determined.

To more certainly prevent rotation of the solar panel8and to fix the solar panel8against the pushing of the contact springs87, it is preferable that the solar panel8be screwed near the contact springs87.

In this embodiment, all of the three contact parts84including the contact part84that abuts the contact springs87have screw holes85. Through the screw holes85, screws72(seeFIG.3andFIG.7) are inserted from above the date indicator holder7to screw the date indicator6and the solar panel8on the module5. InFIG.3, the dashed lines show the points in which the screws72are inserted.

On the date indicator6, the date indicator holder7is disposed.

The date indicator holder7has a cut-out part71(seeFIG.3andFIG.8) at a part corresponding to the components mounted on the module5and desired to be visible from outside, such as gear wheels of the wheel mechanism52. The shape of the cut-out part71is not limited to the illustrated example. The positions and areas of the cut-out parts are determined according to the positions of components to be exposed outside.

As described above, the date indicator holder7is screwed on the module5with screws72along with the date indicator6and the solar panel8.

FIG.9Ais the perspective cross section of the date indicator holder7, the date indicator6, and the solar panel8that are laid on one another.FIG.9Bis the enlarged cross section showing part of the date indicator holder7, the date indicator6, and the solar panel8laid on one another.

As shown inFIG.9AandFIG.9B, on the circumferential surface of the date indicator holder7, a step part73is formed. The height of the step part73is almost equal to the height of the frame61(in this embodiment, the second frame part61b). The outer edge of the frame61is positioned under the step part73, so that the position of the date indicator6, including the frame61, in the up-down direction is determined. Thus, the date indicator6is restrained from rising up.

The step part73has a stand part74. The stand part74extends along the inner circumferential surface of the frame61, and serves as a wall part that restrains the date indicator6including the frame61from moving in the surface direction (the radial direction). Thus, the stand part74serves as a position determiner that determines the position of the date indicator6in the radial direction. Thus, at the inside in the radial direction of the date indicator6, the date indicator6is held down from above, so that the gear end of the date indicator6is prevented from being pushed upward by the contact springs87. Accordingly, the gear62of the date indicator6can accurately engage with the gear wheel of the wheel mechanism52.

When the date indicator6is under the step part73of the date indicator holder7, the invisible-side surfaces of the date indicator holder7and the date indicator6are almost flush, as shown inFIG.9B. The invisible-side flush surfaces are positioned on the visible-side of the solar panel8. The solar panel8is therefore prevented from moving upward.

The date indicator holder7also holds the components on the module5and restrains the components from shifting. Thus, the positions of the components mounted on the module5, such as an hour wheel, are also determined.

Next, the effect of this embodiment is described.

In this embodiment, the wheel mechanism52and so forth are mounted on the front and back surfaces of the main plate51of the module5. Over the module5(at the visible side of the timepiece), the ring-shaped solar panel8is disposed.

The contact springs87are disposed between the contact part84of the solar panel8and the module5. The solar panel8is electrically connected to the board57via the contact springs87.

The contact parts84of the solar panel8are fit into the recess parts55formed in the main plate51, so that the solar panel8is restrained from rotating in the circumferential direction. The position of the solar panel8is thus determined.

The date indicator6is laid over the solar panel8, and the date indicator holder7is placed on the date indicator6to hold the date indicator6from above. The date indicator holder7, the date indicator6, and the solar panel8are altogether screwed on the module5with screws72.

The date indicator holder7, the date indicator6, the solar panel8, and the module5combined together are then housed in the timepiece case1along with the other components of the timepiece (e.g., hands), and the back lid is attached to the timepiece case1. Thus, the timepiece is completed.

According to the above configuration, the central part of the timepiece100is not covered by the solar panel8or other components. The mechanical structure of the timepiece, such as the wheel mechanism52, are therefore exposed.

Part of the date indicator6except the letter parts and so forth is through holes. The date indicator6therefore blocks less light when placed on the solar panel8, and the solar panel8can generate a sufficient amount of electric power without a solar panel that covers the entire front surface of the timepiece.

The date indicator6is three-dimensionally formed by making through holes in metal material (by lightening metal material) and has a stronger presence as compared with a two-dimensional date indictor on which dates are printed. Such a date indicator6allows the base color, the uneven surface, the division lines82, and the cell connectors83of the solar panel8to be inconspicuous. The date indicator6thus contributes to an excellent appearance of the timepiece.

As described above, according to the present disclosure, the timepiece100includes the date indicator6and the ring-shaped solar panel8as a solar battery that is positioned at the invisible side of the date indicator6. The date indicator6includes the frame61that has the gear62that engages with the gear wheel driven to rotate and the letter parts64supported by the frame61via the bridge(s)63.

As the solar panel8is ring-shaped, the central part of the timepiece100is not covered by the solar panel8or other components. The mechanical structure of the timepiece, such as the wheel mechanism52, can therefore be exposed.

The date indicator6, which includes the frame(s)61, the bridges63, and the letter parts64, is three-dimensionally formed. When such a date indicator6is placed over the solar panel8, the base color, the uneven surface, the division lines82, and the cell connectors83of the solar panel8become inconspicuous.

The date indicator6thus contributes to the substantial, solid, and excellent appearance of the timepiece.

Since the date indicator6consists of minimum parts, such as the frame(s)61, the bridges63, and the letter parts64, the date indicator6blocks less light when placed over the solar panel8. Accordingly, the solar panel8can generate a sufficient amount of electric power without a solar panel that covers the entire front surface of the timepiece.

In this embodiment, the gear wheel that engages with the gear62of the frame61is the gear wheel521that constitutes the wheel mechanism52(seeFIG.1, etc.).

According to such a configuration, the date indicator6rotates as the gear wheel521constituting the wheel mechanism52rotates.

In this embodiment, the solar panel8is divided into multiple cells81by the division lines82. When the date indicator6is stationary, the division lines82overlap with the bridges63of the date indicator6.

The date indicator6does not rotate except when the date is updated. The date indictor6is normally in a stationary state when the user uses the timepiece100.

In the stationary state, the bridges63of the date indicator6overlap with the division lines82, thereby hiding the division lines82and making the division lines82inconspicuous. This allows the timepiece to have an excellent external appearance.

In this embodiment, the shape of the division lines82corresponds to the shape of the bridges63.

Such division lines82are more certainly inconspicuous when hidden by the bridges63of the date indicator6.

In this embodiment, the solar panel8has the contact parts84at the inside or outside of its ring-shaped main body, the contact parts84being electrically connected to the board57.

With the contact parts84, the solar panel8can be in contact with the board57without reducing the effective electricity generation region of the ring-shaped main body.

In this embodiment, the contact parts84also function as a rotation preventer that prevents the solar panel8from rotating in the circumferential direction.

In this embodiment, the projection parts that project outward or inward from the ring-shaped main body are used as the contact parts84, and the contact parts84are fitted into the recess parts55of the module5. The contact parts84thus easily restrain the solar panel8from rotating in the circumferential direction and determine the position of the solar panel8.

In this embodiment, the solar panel8further includes the date background region86at a part corresponding to the date indication position where the date indicator6indicates a date. The date background region86is colored so as to be clearly distinguishable from the date indicator6.

With the date background region86, the timepiece clearly indicates the currently selected date for the user.

In this embodiment, the frame61of the date indicator6includes the first frame part61aand the second frame part61bthat is inside the first frame part61a. The letter parts64are supported between the first frame part61aand the second frame part61bvia the bridge(s)63.

Such a date indicator6can retain a high level of shock resistance.

In this embodiment, part of the date indicator6except the frame61, the bridges63, and the letter parts64are through holes.

Such a date indicator6blocks less light when placed over the solar panel8, so that the solar panel8can generate a sufficient amount of electric power without a solar panel that covers the entire front surface of the timepiece.

With the through holes, the date indicator6is made three-dimensional. Such a date indicator6looks substantial, solid and excellent as compared with a date indicator formed by printing letter parts on a plate member, for example.

Although the embodiment of the present invention has been described, the embodiment is not intended to limit the present invention and can be variously modified without departing from the scope of the invention.

For example, in the above embodiment, the solar panel8includes the cell connectors83that connect the cells81and that are formed on the outer edge parts of the solar panel8along the division lines82. However, the position and shape of the cell connectors83are not limited to the above embodiment.

For example, as shown inFIG.10andFIG.11, the cell connectors83of the solar panel8amay be formed in the middle of the respective division lines82.

In such a case, as shown inFIG.12as an example, each of the letter parts64is disposed in the middle of the bridge63formed across the first frame part61aand the second frame part61b.

According to such a configuration, the letter parts64of the date indicator6overlap with the cell connectors83when the date indictor6bis stationary, as shown inFIG.13. The cell connectors83are thus hidden by the letter parts64and become inconspicuous.

Further, when the date indicator6bis stationary, the bridges63that support the letter parts64overlap with the division lines82of the solar panel8. The division lines82are also inconspicuous, and the timepiece1can retain a beautiful external appearance.

As shown inFIG.13, the division line82and the cell connector83may be formed so as to be within the date background region86, and the division line82, the cell connector83, and the date background region86may be altogether colored with the color of the date background region86(e.g., white). Accordingly, the division line82and the cell connector83are inconspicuous even when the positions of the bridge63and the letter part64of the date indicator6bslightly deviate from the position of the division line82and the cell connector83.

Further, as shown inFIG.14, the cell connectors83of the solar panel8bmay be formed along the outer circumference of the solar panel8, and the width of each cell connector83in the radial direction may be narrowed.

In such a case, most part of the cell connectors83is covered and hidden by the first frame part61a, which is formed outside the date indicator6c, as shown inFIG.15as an example. The cell connectors83thus become inconspicuous.

Further, the parting member3may be formed to extend over the cell connectors83, so that the cell connectors83are hidden more certainly.

Further, as shown inFIG.15, the division line82and the cell connector83may be formed within the date background region86, and the division line82, the cell connector83, and the date background region86may be altogether colored with the color of the date background region86(e.g., white), so that division line82and the cell connector83are inconspicuous.

The arrangement of the letter parts64of the date indicator6is not limited to the above embodiment. For example, as in the date indicator6cshown inFIG.16, the letter parts64indicating the dates from “1” to “31” may be arranged counterclockwise.

For another example, like the date indicator6dshown inFIG.17, the letter parts64indicating the dates from “1” to “31” may be arranged on every other date.

Although not illustrated, one-digit dates (i.e.,1to9) may be appropriately mixed with the two-digit dates (i.e.,11to31). In the case, the letter parts64may be arranged such that the letter parts64having a smaller area (e.g.,1,7) are next to the letter parts64having a larger area (e.g.,28,29).

Some letter parts64have a larger area, while other letter parts64have a smaller area. Therefore, the area of each cell81that effectively receives light (effective light-receiving area) varies depending on the letter parts64that overlap with the cell81. When the letter parts64are arranged such that “1” and “31” are next to each other as in the above embodiment or the example ofFIG.16, the effective light-receiving area greatly differs among the cells81. To deal with this, the letter parts64may be arranged such that letter parts corresponding to a large effective light receiving area and letter parts corresponding to a small effective light receiving area are mixed. For example, the letter parts64indicating1to31may be arranged on every other day, so that variations of effective light receiving areas become small among the cells81.

This allows the effective electricity generation regions uniform among the cells81. Accordingly, the generation efficiency increases.

To restrain variations of effective light receiving areas, the design of the letter parts64may be adjusted, instead of or as well as adjusting the order of dates. For example, letters corresponding to a large effective light receiving area may be formed with thicker metal lines, whereas letters corresponding to a small effective light receiving area may be formed with thinner metal lines.

For another example, the level of lighting the metal material may be adjusted. For example, letters corresponding to a large effective light receiving area may be made of thick metal material, whereas letters corresponding to a small effective light receiving area may be made of thin metal material.

The shapes of the solar panel8and the cells81constituting the solar panel8are not limited to the substantial ring-shape in the above embodiment.

When the timepiece100has a rectangular shape, the solar panel8may also have a rectangular frame shape, for example.

In the above embodiment, the solar panel8includes five cells81ato81eas an example. However, the number of cells81constituting the solar panel8is not limited to a specific number. The number of cells may be more than or less than five (e.g., six, three) in the above embodiment.

The way of dividing the solar panel8is also not specifically limited. In the above embodiment, the ring-shaped solar panel8is divided into cells81by the radial division lines82that extend in the radial direction of the solar panel8, as an example. However, the division lines that divide the solar panel8into multiple cells81are not limited to such lines.

For example, the solar panel8may be divided into multiple ring-shaped cells by concentric division lines.

In a case where the user wears the timepiece100as shown inFIG.1, part of the timepiece100may be covered by the sleeve of the cloth of the user, for example. If the solar panel8is divided into cells81by the radial division lines82that extend in the radial direction, some of the cells81may completely hidden behind the sleeve.

On the other hand, if the solar panel8is divided into ring-shaped cells by the concentric division lines, the cells are not completely hidden by the sleeve or the like, and the timepiece1can avoid the state where the solar panel generates no electric power (i.e., the state where the timepiece1completely loses the electricity generation function).

In the above embodiment, the date background region86is formed on the solar panel8as an example. However, the date background region86may not be necessarily formed on the solar panel8.

As long as the data indication position of the date indicator6(the position where the current date is indicated) is clearly noticeable for the user, any configuration is applicable. For example, the windshield member2or the parting member3may have a frame that defines the date indication position.

In the above embodiment, a dial plate is not provided. However, a ring-shaped dial plate may be provided between the solar panel8and the date indicator6, for example.

In such a case, the dial plate is made to have a high light transmittance in order to minimize the decrease in generation efficiency of the solar panel8. For example, the dial plate may be made of transparent material, such as glass, on which printing is performed. When a dial plate is provided, the division lines82and the cell connectors83of the solar panel8are more certainly inconspicuous. The dial plate can also prevent direct contact between the date indicator6and the solar panel8, so that the date indicator6rotates smoothly.

When a dial plate is provided, the dial plate may have a frame that defines the date indication position.

In the above embodiment, the solar panel8(solar battery) is ring-shaped as an example. However, the shape of the solar battery is not limited to the ring shape but may be another shape.

In the above embodiment, the frame61of the date indicator6is ring-shaped. However, the shape of the frame61and the date indicator6including the frames61is not limited to the ring shape but may be another shape. The frame61may not extend along the whole circumference of the electronic device (e.g., timepiece100) in a plan view. The frame61may extend only part of the whole circumference of the electronic device.

Although the timepiece100is disclosed as an example of the electronic device, the electronic device is not limited to a timepiece.

The electronic device may be any device including: the date indicator6that includes letter parts and non-letter parts different from the letter parts, the non-letter parts being through holes; and the solar battery (solar panel8) that is disposed below the date indicator6. For example, the electronic device may be a calendar device that does not indicate time but indicates the date, the day of the week and so forth, for example.

This application claims the benefit of Japanese Patent Application No. 2021-152858, filed on Sep. 21, 2021 which is hereby incorporated by reference in in its entirety.