Electronic timepiece with solar cell

To provide an electronic timepiece with a solar cell whereby a movement can be reduced in size and whereby a calendar function using a calendar wheel can be achieved, an electronic timepiece with a solar cell is provided with: a solar cell, a character plate, a ground plate arranged on a back surface of the solar cell, a ring-shaped date wheel arranged between the character plate and the ground plate, and a circuit board electrically connected to an electrode of the solar cell via a conduction spring. The conduction spring is arranged on the inside of the date wheel when in plan view seen from the character plate side. In comparison to a case where a conduction spring is provided to the outside of a date wheel, the movement can be reduced in size, and because the date wheel can be arranged, a calendar function can be achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2011-269892 filed on Dec. 9, 2011. The entire disclosure of Japanese Patent Application No. 2011-269892 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an electronic timepiece with a solar cell.

2. Background Technology

In an electronic timepiece with a solar cell, to which a solar cell is provided, a conduction part where a conduction spring (a coil spring) is used is provided to an outer peripheral part of a movement, in order for a secondary battery or the like to be charged with power generated by the solar cell (for example, see FIG. 11 of Patent Citation 1).

When the conduction part is provided to the outer periphery of the movement, there is an inevitable increase in the size of the movement in comparison to an ordinary electronic timepiece driven by a primary battery. For this reason, a problem has emerged in that it is difficult to configure a smaller-sized electronic timepiece with a solar cell, especially one suitable for use by women. In view whereof, in FIG. 4 of Patent Citation 1, a solar cell connection spring is arranged in a spatial region enclosed by a trigger piece, the main body of a yoke, and a yoke return spring part.

Japanese Laid-open Patent Publication No. 2004-239714 (Patent Document 1) is an example of the related art.

SUMMARY

Problems to Be Solved by the Invention

However, as is illustrated in FIG. 4 of Patent Citation 1, a new problem emerges in that when the solar connection spring is arranged in the vicinity of the trigger piece and/or the yoke, then it is difficult to provide a calendar function. More specifically, the trigger piece and the yoke are disposed close to the winding stem. A date wheel or similar calendar wheel is disposed on an upper side of the winding stem, and a calendar window formed on a character plate displays calendar information. The calendar wheel is formed in a ring shape (an annular shape), and is arranged between the solar cell and the movement, and therefore there is interference between the solar connection spring and the arrangement position. For this reason, in Patent Citation 1, a problem emerges in that it is not possible to use the calendar wheel to achieve a calendar function.

An advantage of the invention is to provide an electronic timepiece with a solar cell whereby a movement can be reduced in size and whereby a calendar function using a calendar wheel can be achieved.

Means Used to Solve the Above-Mentioned Problems

The electronic timepiece with a solar cell of the invention includes: a solar cell; a light-transmissive character plate arranged on a timepiece front side of the solar cell; a ground plate arranged on a back surface of the solar cell; a ring-shaped calendar wheel disposed between the character plate and the ground plate; and a circuit board electrically connected to an electrode of the solar cell via a conduction spring, the conduction spring being arranged on the inside of the calendar wheel in plan view seen from the character plate side.

In the electronic timepiece with a solar cell of the invention, the conduction spring electrically connecting the electrode of the solar cell and the circuit board is arranged in a space on the inside of the ring-shaped calendar wheel, which is a date wheel or the like. For this reason, the movement can be reduced in size in comparison to a case where the conduction spring is provided to the outside of the calendar wheel. As such, an electronic timepiece with a solar cell for use by women can also be readily designed.

In the case where the conduction spring is provided to the outside of the calendar wheel, when a model in which the calendar wheel has a large outer diameter is to be designed, it becomes necessary to change the arrangement position of the conduction spring, and the electrode position of the solar cell must also be changed. By contrast, according to the invention, because there is no interference with the conduction spring even when the outer diameter dimension of the calendar display is increased, there is no need to change the electrode position of the solar cell or the arrangement position of the conduction spring when a model in which the calendar wheel has a large outer diameter is being developed as the electronic timepiece with a solar cell. For this reason, a movement that includes the solar cell, the conduction spring, the circuit board, and the like can be created to be shared among a variety of models in which the outer diameter dimension of the calendar wheel is different, and also costs can be reduced.

It is also possible to reduce the distance between the calendar wheel and the outer circumference of the timepiece (an outer casing) in comparison to the case where the conduction spring is provided to the outside of the calendar wheel. For this reason, the degree of freedom in the formation position of the calendar window for offering a view of the calendar wheel is improved, and the degree of freedom in the design variation of the character plate can be improved.

Preferably, the electronic timepiece with a solar cell of the invention includes a solar cell holding member fixed to the back surface of the solar cell, the solar cell holding member and the ground plate each having opposing surfaces provided to the inside of the calendar wheel in plan view seen from the character plate side, a hook part being formed on one of the opposing surfaces and a guide hole formed to allow for the hook part to be arranged being formed on the other of the opposing surfaces, and the solar cell holding member being rotated with respect to the ground plate in the state where the hook part has been arranged within the guide hole to lock a peripheral edge of the guide hole onto the hook part, whereby the solar cell holding member is fixed to the ground plate.

In the electronic timepiece with a solar cell of the invention, opposing surfaces provided to the inside of the calendar wheel in plan view seen from the character plate side are provided to the ground plate and to the solar cell holding member fixed to the back surface of the solar cell. The hook part is provided to one of the opposing surfaces and the guide hole is provided to the other. Because the hook part and the guide hole are formed on the opposing surfaces on the inside of the calendar wheel, the fixation position at which the solar cell and the solar cell holding member are fixed to the ground plate can be set so as to be close to the arrangement position of the conduction spring. For this reason, even when a pressing force is applied to the electrode of the solar cell by the conduction spring, the pressing force can be borne by a locking structure of the hook part and the guide hole. As such, the pressing force of the conduction spring can be prevented from majorly deforming the solar cell even in a case where the solar cell used is a film solar panel in which the base material is made of a plastic film.

Also, the solar cell holding member need not be projected out to the outer periphery of the solar cell, and will not be visible through the character plate. For this reason, there is no need to arrange a visual limiting member for covering the solar cell holding member, and any constraint of the visual limiting diameter can also be eliminated. Accordingly, the degree of freedom of the size of the character plate and of the visual limiting diameter can be increased, and in a case where the electronic timepiece with a solar cell is to be configured to be a wristwatch, then the degree of freedom of model variation can also be increased, from a large-sized wristwatch having a large visual limiting diameter to a wristwatch for use by women, having a small visual limiting diameter. In addition, because the solar cell can be fixed at the ground plate, i.e., in the vicinity of the center of the movement, the size of the solar cell can be freely set within the size of the movement. For this reason, the size of the solar cell can be set to a minimum size on the basis of the amount of power generation required even in a case where the size of the movement is different. As such, the size of the solar cell need not be increased in accordance with the size of the movement, and the cost of the solar cell can thus also be reduced.

Furthermore, because the solar cell holding member is rotated with the hook part arranged in the guide hole to lock the peripheral edge of the guide hole onto the hook part and thereby fix together the solar cell holding member and the ground plate, the need for a connecting component, such as a screw, for fixing same can be obviated. For this reason, in comparison to a case where the solar cell is fixed to the ground plate with a screw, the number of components can be lowered and costs can be reduced; because consideration also need not be given to interference with a component arranged on the back surface side of the ground plate, an electronic timepiece with a solar cell posing even less of a burden on the global environment can be easily designed.

In the electronic timepiece with a solar cell of the invention, preferably, the solar cell holding member includes a positioning part for engaging with a positioning projection formed in the ground plate to carry out positioning in the direction of rotation, as well as an insertion hole into which the conduction coil is inserted, and the positioning part and the insertion hole are arranged so as to be adjacent to each other.

Because the positioning projection formed on the ground plate and the positioning part provided to the solar cell holding member are engaged together, the solar cell holding member can be prevented from rotating with respect to the ground plate in a direction inverse to the direction of locking of the guide hole and the hook part and the peripheral edge of the guide hole can be prevented from disengaging from the hook part.

Also, because the positioning part provided to the solar cell holding member and the insertion hole into which the conduction spring is inserted are arranged so as to be adjacent to each other, the solar cell holding member and the conduction spring can be more readily attached and detached. More specifically, when the solar cell holding member is to be mounted onto the ground plate, the solar cell holding member is placed atop the conduction spring arranged in the insertion hole and is pressed against the conduction spring, and also the peripheral edge of the guide hole is locked onto the hook part and the positioning part is engaged with the positioning projection while the solar cell holding member is being rotated.

When the positioning part is engaged with the positioning projection, because the positioning part is present near the conduction spring, the conduction spring can also be pushed in at the same time when the positioning part is being pushed in. As such, in comparison to a case where the positioning part and the conduction spring are arranged at positions spaced apart from each other, the solar cell holding member can be more easily mounted.

Also, when the positioning part of the solar cell holding member is to be removed from the positioning projection, too, then this can be done while the conduction spring near thereto is being pressed, and the solar cell holding member can also be easily removed.

In the electronic timepiece with a solar cell of the invention, preferably, the solar cell is arranged on the inside of the calendar wheel in plan view seen from the character plate side.

When the solar cell is arranged in the space on the inside of the calendar wheel, then the solar cell and the calendar wheel can be arranged at an identical height position in the thickness direction of the timepiece. For this reason, the thickness dimension of the movement can be reduced. Also, the surface area of the solar cell can be lowered, and therefore the costs of the solar cell can be reduced.

In the electronic timepiece with a solar cell of the invention, preferably, the height position of an upper surface of the calendar wheel in the thickness direction of the timepiece is positioned above a lower surface of the solar cell.

When the upper surface of the calendar wheel is set to be above the lower surface of the solar cell in terms of the height position in the thickness direction of the timepiece, the distance between the upper surface of the calendar wheel and the character plate arranged atop the solar cell can be lowered. For this reason, the impression of a recessed setting of the calendar wheel which can be viewed from the calendar window of the character plate can be attenuated, and the date and the like can also be more easily read.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of the invention shall now be described with reference to the accompanying drawings.

Schematic Configuration of the Electronic Timepiece with a Solar Cell

FIG. 1is an exploded perspective view of a timepiece main body10of an electronic timepiece1with a solar cell according to the present embodiment. The electronic timepiece1with a solar cell is schematically constituted of the timepiece main body10as well as an outer case (not shown) for accommodating the timepiece main body10, and is of a wristwatch type which a user utilizes worn on the wrist.

Configuration of the Timepiece Main Body

The timepiece main body10, as illustrated inFIG. 1, is provided with a movement2, a character plate-receiving ring member3, a solar cell4, and a light-transmissive character plate5arranged on the front side of the solar cell4. The movement2, as is also illustrated inFIG. 2, adopts a general configuration incorporating a ground plate20, a circuit board, a stepping motor, a driving wheel train, and the like, and therefore a description thereof has been omitted. The outer case also has a general configuration, and a description thereof has thus also been omitted.

Configuration of the Ground Plate

A date wheel21, which is a calendar wheel, is arranged on an upper surface of the ground plate20. Drive teeth211are formed on an inner peripheral surface of the date wheel21. Guide parts221,222,223for guiding the inner peripheral surface of the date wheel21(the drive teeth211) are formed so as to project out on the ground plate20. A date-turning wheel23which rotates in meshed engagement with the drive teeth211of the date wheel21and a day jumper24for regulating the position thereof after rotation when the date wheel21has been rotated one pitch by the date-turning wheel23are provided to an inner peripheral side of the date wheel21on the upper surface of the ground plate.

Three hook parts25,26,27for fixing the solar cell4are also formed on the inner peripheral side of the date wheel21on the upper surface of the ground plate20. The hook part25, as is also illustrated inFIG. 2, is provided so as to be adjacent to the guide part221, and is provided with an upright part251standing upright from the ground plate20and with an extension part252extending to the side from the upright part251. As such, a recess for locking the solar cell4is formed between the upper surface of the ground plate20and the extension part252. The other hook parts26,27are also configured to be provided with an upright part and an extension part similarly with respect to the hook part25. Positioning projections28are provided projecting out at two locations on the guide part223.

Also, as shall be described below, two insertion holes225into which a conduction spring7is to be inserted are formed at a position adjacent to the positioning projection28formed closer to the hook part25from among the two positioning projections28provided to the ground plate20, i.e., are formed on the inner peripheral side of the date wheel21.

Configuration of the Character Plate-Receiving Ring Member

The character plate-receiving ring member3is formed in an annular shape using a non-light-transmissive-material (for example, a synthetic resin), and is colored to be of the same type of color as the solar cell4described below. The character plate-receiving ring member3has a support hook part (not shown) formed at two mutually facing locations with the plane center thereof interposed therebetween. The support hook parts engage with a back surface side of the movement2, and the character plate-receiving ring member3holds the movement2.

An upper surface30of the character plate-receiving ring member3is provided with two first character plate fixing parts33arranged so as to be mutually facing with the center of the character plate-receiving ring member3interposed therebetween, and also with two second character plate fixing parts34also arranged so as to be mutually facing. The first character plate fixing parts33are constituted of a substantially prismatic-shaped engagement projection formed so as to project out toward the character plate5from the upper surface30. The second character plate fixing parts34are constituted of a cylindrical-shaped engagement projection formed so as to project out toward the character plate5from the upper surface30.

Configuration of the Solar Cell

The solar cell4, as illustrated inFIG. 1, is provided with a base material41having a substantially cylindrical shape in plan view and a solar cell light-receiving unit42formed on a front surface side of the base material41. The base material is constituted of an insulating material such as a film made of a synthetic resin. The light-receiving unit42is configured by stacking onto the front surface of the base material41a metal electrode layer, a semiconductor layer, an insulating layer, a wiring electrode layer, a light-transmissive sealing resin layer, or the like. The light-receiving unit42is formed separated into three regions. More specifically, three fan-shaped light-receiving units42are formed on the front surface of the solar cell4. In the present embodiment, the generated electrical voltage is enhanced by connecting in series the outputs of the three light-receiving units42.

Solar light transmitted through the character plate5hits against the light-receiving units42, whereby the solar cell4generates electricity, and the power generated by the light-receiving units42, as is also illustrated inFIG. 3, is charged in a secondary cell29provided to the movement via a conduction spring including a coil spring or the like; the circuit board and the like are driven by the output of the second cell29. The solar cell4is set such that outer diameter dimension is of an equal size to the inner diameter dimension of the date wheel21.

Configuration of the Solar Cell Holding Member

A solar cell holding member45is fixed to the back surface of the solar cell4. The solar cell holding member45is constituted of a stainless steel plate or a plastic plate, and is formed in a substantially disc shape. The solar cell holding member45is bonded to the base material41of the solar cell4using an adhesive agent or adhesive tape. The solar cell holding member45is formed to be slightly smaller in size than the solar cell4, and the entirety thereof is covered by the base material41of the solar cell4. For this reason, the solar cell holding member45will not be exposed from the solar cell4and will not be visible from the character plate5side.

The solar cell holding member45, when mounted onto the ground plate20, is arranged above the drive teeth211of the date wheel21(on the character plate5side) and is also provided with a function for positioning so as to prevent the date wheel21from moving toward the character plate5side. More specifically, the solar cell holding member45functions like a date wheel holder for positioning the date wheel21in the cross-section direction (the timepiece thickness direction).

The solar cell holding member45, as is also illustrated inFIG. 4, is provided with three guide holes46,47,48corresponding to the hook parts25,26,27. The guide holes46,48are given a groove shape communicating to the outer periphery of the solar cell holding member45. The guide holes46,47,48are formed so as to allow the hook parts25,26,27to be arranged in the respective holes thereof. More specifically, the size and/or formation position of the guide holes46,47,48is set in accordance with that of the hook parts25,26,27.

As is also illustrated inFIG. 2, an outer peripheral part453coupled to a center part451of the solar cell holding member45via a bent part452has a height position (position in the timepiece thickness direction) located closer to the character plate5than the center part451, due to the fact that the bent part452has been bent. The outer peripheral part453is arranged above the drive teeth211of the date wheel21and carries out positioning of the date wheel21.

Locking parts461,471,481which are locked onto the hook parts25,26,27are formed on a portion of the center part451facing each of the guide holes46,47,48. These locking parts461,471,481are formed one step lower than the center part451toward the movement2.

A positioning part482extended out from the outer peripheral part453is formed on the guide hole48. A hole483for engaging with one of the two positioning projections28is formed on the positioning part482.

A hole462serving as a positioning part for engaging with one of the two positioning projections28and two insertion holes463into which the conduction spring7is to be inserted are all formed on the outer peripheral part453provided between the guide holes46,48, i.e., on an inner peripheral side of the date wheel21. The conduction spring7is therefore arranged on the inside of the date wheel21when in plan view seen from the character plate5side. The hole462and the insertion hole463are arranged at positions that are adjacent on the inside of the date wheel21. The insertion hole463is formed to a size that does not come into contact with the conduction spring7. A configuration can also be adopted such that an insulating member is arranged on an inner peripheral surface of the insertion hole463to prevent electricity from being conducted even when there is contact with the conduction spring7. Electrodes electrically connected to the conduction spring7are therefore formed at positions corresponding to the insertion holes463of the solar cell holding member45on the back surface of the base material41of the solar cell4. Also, as illustrated inFIG. 3, an electrode on a circuit board8side electrically connected to the conduction spring7is formed also at positions corresponding to the insertion holes225of the ground plate20in the circuit board8arranged on the back lid side of the ground plate20. The circuit board8is mounted onto the ground plate20by a circuit-pressing plate9. The solar cell holding member45is bonded to the base material41of the solar cell4at a portion where the outer peripheral part453is.

Configuration of the Character Plate

The character plate5is formed of a light-transmitting material to a size that covers the entirety of the light-receiving unit42of the solar cell4, as illustrated inFIGS. 1 and 2. The character plate5can be of a size that covers at least the entirety of the light-receiving unit42, or can be of a size greater than that of the character plate-receiving ring member3. The character plate5is provided with four extension parts51extending out from the outer peripheral edge in the radial direction, as well as with two first engagement parts52formed by making a cut into each of the extension parts51in the shape of a “U” in plan view, and two second engagement parts53formed by making a cut in a semi-circular shape in plan view.

At least the extension parts51are placed on top of a top surface30of the character plate-receiving ring member3, whereby the character plate5is supported by the character plate-receiving ring3. The first engagement parts52are fitted into first character plate fixation parts33, and the second engagement parts53are fitted into second character plate fixation parts34. The character plate5is thereby positioned and fixed in the direction of rotation with respect to the character plate-receiving ring member3. The calendar window55, from which the date wheel21is exposed, is formed on the character plate5.

Assembly of the Timepiece Main Body

A method for assembling the timepiece main body10shall now be described. Firstly, the movement2is held with the character plate-receiving ring member3. At this time, the character plate-receiving ring member3is inserted in from above the movement2, and is supported such that the support hook parts of the character plate-receiving ring member3are hooked onto the base surface of the movement2. Depending on the size of the timepiece case, a frame (not shown) is also mounted onto the movement2.

Next, the solar cell4is mounted onto the movement2by the following procedure. Firstly, the conduction spring7is arranged in the insertion holes225of the ground plate20. Next, the hook parts25,26,27are arranged on the inside of the guide holes46,47,48of the solar cell holding member45, which has been bonded to the back surface of the solar cell4. Then, together with the solar cell4, the solar cell holding member45is rotated clockwise while also being pushed in on the movement2side, and the locking parts461,471,481are locked into the hook parts25,26,27as illustrated inFIG. 5. The solar cell4and the solar cell holding member45are thereby mounted onto the ground plate20positioned in the timepiece thickness direction. The hole483of the positioning part482of the solar cell holding member45as well as the hole462formed on the outer peripheral part453are both engaged with the positioning projection28, and the solar cell holding member45is positioned in the direction of rotation. At this time, the conduction spring7is brought into contact with an electrode formed on the back surface of the solar cell4and with an electrode of the circuit board8, and allows conduction through the solar cell4and the circuit board8.

The solar cell4and the solar cell holding member45are thus fixed to the movement2, as illustrated inFIG. 5, by the foregoing procedure. Also, the solar cell4and the solar cell holding member45are positioned with respect to the direction of rotation of the ground plate20by the engagement of the holes462,483into the positioning projection28.

Next, the character plate5is held by the character plate-receiving ring member3from the front surface side of the solar cell4. More specifically, the first engagement part52is fitted into the first character plate fixation part33of the character plate-receiving member3, and the second engagement part53is fitted into the second character plate fixation part34. The character plate5is thereby placed on top of the top surface30of the character plate-receiving member3and positioned with respect to the thickness direction. Also, the character plate5is positioned with respect to the direction of rotation of the character plate-receiving member3by the fitting of the engagement part52,53into the character plate fixation parts33,34. The foregoing is the manner in which the timepiece main body10is assembled.

According to the electronic timepiece1with a solar cell as in the embodiment described above, the following effects are achieved.

(1) Because the conduction spring7electrically connecting the solar cell4and the circuit board8is arranged in a space on the inside of the date wheel21, the movement2can be reduced in size in comparison to a case where the conduction spring is provided to the outside of the date wheel21. For this reason, an electronic timepiece with a solar cell for use by women, too, can be easily designed and manufactured. Also, because there is no interference from the conduction spring7even when the outer diameter dimensions of the date wheel are large, there is no need to change the electrode position of the solar cell4nor the arrangement position of the conduction spring7when a model having a large outer diameter of the date wheel21is developed as the electronic timepiece1with a solar cell. For this reason, a movement2that includes the solar cell4, the conduction spring7, and the circuit board8can be created to be shared among a variety of models in which the outer diameter dimension of the date wheel21is different, and also costs can be reduced. Also, the distance between the date wheel21and the timepiece outer periphery (the outer case) can be reduced in comparison to the case where the conduction spring7is provided to the outside of the date wheel21. For this reason, the degree of freedom in the position of the calendar window55formed in the character plate5is improved, and the degree of freedom in the design variation of the character plate5can be improved.

(2) The hook parts25,26,27are formed on the upper surface of the ground plate20of the movement2, the guide holes46,47,48having the locking parts461,471,481are formed on the solar cell holding member45bonded to the back surface of the solar cell4, and the locking parts461,471,481are locked onto the hook parts25,26,27to mount the solar cell4onto the movement2. For this reason, the position of fixation of the solar cell4and the solar cell holding member45to the ground plate20can be designed to be close to the arrangement position of the conduction spring7. As such, even when a pressing force is applied to the electrode of the solar cell4by the conduction spring7, the pressing force can be borne by the locking structure of the hook parts25,26,27and the guide holes46,47,48. As such, the solar cell4can be prevented from majorly deforming due to the pressing force of the solar cell7, even in a case where the base material is made using a film solar panel made of a plastic film as the solar cell4.

(3) Because there is no need to provide a hook part to the outer periphery of the solar cell holding member45, the hook parts will not protrude from the outer periphery of the solar cell4and will not be seen from through the character plate5. As such, there is no need to arrange a visual limiting member for covering the solar cell holding member45, and any constraint of the visual limiting diameter can also be eliminated. Accordingly, the degree of freedom of the size of the character plate5and the size of the visual limiting diameter can be increased, and in a case where the electronic timepiece1with a solar cell is to be configured as a wristwatch, then the degree of freedom of model variation can also be increased, from a large-sized wristwatch having a large visual limiting diameter to a wristwatch for use by women, having a small visual limiting diameter.

(4) Because the solar cell4can be fixed in the vicinity of the center of the ground plate20, i.e., of the movement2, the size of the solar cell4can be freely set within the size of the movement2. For this reason, the size of the solar cell4can be set to a minimum size on the basis of the amount of power generation required even in a case where the size of the movement is different2. As such, the size of the solar cell4need not be increased in accordance with the size of the movement2, and the cost of the solar cell4can thus also be reduced. Also, in the fixation between the solar cell holding member45and the ground plate20, because the solar cell holding member45is rotated with the hook parts25,26,27arranged in the guide holes46,47,48to lock the locking parts461,471,481on the peripheral edges of the guide holes46,47,48onto the hook parts25,26,27, there is no need for fixation using a separate screw or other connecting component. For this reason, in comparison to a case where the solar cell4is fixed to the ground plate20with a screw, the number of components can be lowered and costs can be reduced; because consideration also need not be given to interference with a component arranged on the back surface side of the ground plate20, the electronic timepiece1with a solar cell can be easily designed.

(5) Because the solar cell holding member45is provided with the holes462,483for engaging with the positioning projection28formed on the ground plate20, the solar cell holding member45can be rotated with respect to the ground plate20to prevent the locking parts461,471,481from falling out of the hook parts25,26,27. Also, because the hole462and the insertion hole463into which the conduction spring7is inserted are arranged so as to be adjacent to each other, the solar cell holding member45and the conduction spring7are easily removable. More specifically, because the hole462, which is a positioning part for engaging with the positioning projection28is provided close to the conduction spring7, the conduction spring7can be pushed in at the same time as when the portion of the outer peripheral part453where the hole462is formed is being pushed in. As such, in comparison to a case where the positioning part and the conduction spring7are arranged at positions spaced apart from each other, the conduction spring7can be more reliably pushed in and the solar cell holding member45can be more easily mounted. Also, when the hole462, which is a positioning part of the solar cell holding member45, is to be removed from the positioning projection28, too, then this can be done while the conduction spring7near thereto is being pressed, and the solar cell holding member45can also be easily removed.

(6) Because the solar cell4is set to substantially an equivalent size to that of the solar cell holding member45, the surface area of the solar cell4can be reduced and the cost of the solar cell4can be lowered.

(7) Because the solar cell4and the character plate5can be arranged in a stacked fashion without any spacing therebetween, the electronic timepiece1with a solar cell can be reduced in thickness and the impression of a recessed setting of the date wheel21can also be attenuated in comparison to a case where, for example, a structure is adopted in which a solar cell holder is provided fixed between the solar cell4and the character plate5.

(8) Because the solar cell4and the solar cell holding member45are fixed using an adhesive agent or adhesive tape, there will be no exposure of a connecting component on the surface of the solar cell, and a decline in the outer appearance of the electronic timepiece1with a solar cell can be prevented in comparison to a case where a connection component such as a screw is used for fixation.

(9) Because the solar cell holding member45doubles as a component for positioning the date wheel21in a cross-sectional manner, i.e., in the timepiece thickness direction, the number of components can be reduced and the procedure for incorporating same can also be reduced, and thus costs can be lowered. Also, the thickness dimension of the movement2can be reduced in comparison to a case where both the solar cell holding member45and a component for positioning the date wheel21are used.

(10) Because the solar cell holding member45, bonded to the back surface of the solar cell4, can be constituted of a metal such as stainless steel, the solar cell holding member functions not only to mount the solar cell4onto the ground plate20, but also to enhance the strength of the solar cell4itself. As such, a film made of a synthetic resin or the like can be used as the base material41of the solar cell4, and the solar cell4can be reduced in thickness and reduced in cost.

(11) Because the color of the front surface side of the character plate-receiving ring member3can be made to be the same type of color as the solar cell4, the color tones of the solar cell4and the character plate-receiving ring member3can be matched together. For this reason, a difference in the color tone with respect to the character plate-receiving ring member3can be prevented from causing the outer form of the solar cell4to be visible seen through the character plate5, and the outer appearance of the timepiece when seen through the character plate5can be enhanced.

Modifications of the Embodiment

The invention is not to be limited to the above-described embodiment, but rather any modification, improvement, or the like made within a scope capable of achieving the advantage of the invention is intended to be included within the invention. The size of the solar cell4is not limited to the size in the above-described embodiment. More specifically, any size is permissible, provided that adequate power needed to drive the movement2can be ensured. Herein, when the outer diameter of the solar cell4is formed to be smaller than the inner diameter of the date wheel21, then the solar cell4and the date wheel21can be arranged at the same height position (the same positioning in the thickness direction of the timepiece). In such a case, the thickness dimension of the electronic timepiece1with a solar cell can be reduced and a thinner timepiece can be achieved, in comparison to a case where the solar cell4and the date wheel21are arranged at different height positions.

The upper surface position of the date wheel21, i.e., the height position in the timepiece thickness direction can be arranged to be above the lower surface of the solar cell4. In such a case, the distance between the date wheel21and the character plate5, arranged atop the solar cell4, can be reduced. For this reason, the impression of a recessed setting of the date wheel21which can be viewed from the calendar window55of the character plate5can be attenuated, and the date and the like can also be more easily read.

In the above-described embodiment, the character plate-receiving ring member3that was used was annular, but a character plate-receiving ring member having a planar rectangular frame shape can also be used. When a character plate-receiving ring member of such description is used, the character plate or timepiece case can constitute a rectangular model.

In the above-described embodiment, the hook parts25,26,27were formed on the ground plate20side, and the guide holes46,47,48were formed on the solar cell holding member45side, but conversely, the guide holes can be formed on the ground plate20side and the hook parts can be formed on the solar cell holding member45side.

In the above-described embodiment, the solar cell holding member45was fixed to the back surface of the solar cell4with an adhesive agent or adhesive tape, but other methods of fixation can be used to fix same. For example, in a case where the base material41of the solar cell4is a metal plate, then the solar cell holding member45can be fixed with swaging or the like.

In the above-described embodiment, the solar cell holding member45doubled as a member for positioning the date wheel21in the timepiece thickness direction, but the positioning of the date wheel21in the timepiece thickness direction can also be carried out with another component. Also, although the date wheel21was provided as a calendar wheel, a day-of-the-week wheel or other calendar wheel can also be arranged. Furthermore, because the conduction spring7is arranged in a space on the inside of the calendar wheel and the arrangement space of the calendar wheel is easily expanded toward the outer periphery, there can be two types of calendar wheels, such as the date wheel21and a day-of-the-week wheel, arranged therein.

In the above-described embodiment, the color the character plate-receiving member3was the same type of color as that of the solar cell4, but these can also be of different colors. In particular in a case where an exposed surface of the character plate-receiving member3is covered by a dial ring or other visual limiting member, there is no need for the color of the character plate-receiving ring member3to be matched to that of the solar cell4. In the above-described embodiment, a timepiece of the wristwatch type was described as an example of the timepiece according to the invention, but there is no limitation thereto, and a wall-hanging clock or other type of timepiece is also possible.