# US 8,787,121 B2 · Electronic timepiece with solar cell

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- Number: US 8,787,121 B2
- Document ID: US8787121B2
- Status: Granted
- Kind: B2
- Application number: 13/708,130
- Filed: 2012-12-07
- Published: 2013-06-13
- Granted: 2014-07-22
- Earliest claimed: 2011-12-09
- Assignees: Seiko Epson Corporation
- Applicants: Seiko Epson Corporation
- Inventors: Reiko Nagahama
- Web page: https://patentgrep.com/patent/US8787121B2

## CPC

- G04C 10/02: the power supply being a radioactive {or photovoltaic} source
- G04G 9/00: Visual time or date indication means
- G04G 17/04: Mounting of electronic components
- G04G 17/06: Electric connectors, e.g. conductive elastomers
- G04C: ELECTROMECHANICAL CLOCKS OR WATCHES
- G04G: ELECTRONIC TIME-PIECES

## Abstract

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.

## Claims

### Claim 1

An electronic timepiece with a solar cell, the timepiece comprising:
a hand configured to show time;
an axis connected to the hand to rotate the hand, the axis extends in a direction;
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 having a conduction spring, and electrically connected to an electrode of the solar cell via the conduction spring,
the conduction spring being arranged on the inside of the calendar wheel in plan view seen in the direction.

### Claim 2 (depends on 1)

The electronic timepiece with a solar cell as set forth in claim 1, further comprising:
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 the plan view seen in the direction, 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 a 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.

### Claim 3 (depends on 2)

The electronic timepiece with a solar cell as set forth in claim 2, wherein
the solar cell holding member comprises:
a positioning part for engaging with a positioning projection formed in the ground plate to carry out positioning in a direction of rotation, as well as an insertion hole into which the conduction coil is inserted, the positioning part and the insertion hole being arranged so as to be adjacent to each other.

### Claim 4 (depends on 1)

The electronic timepiece with a solar cell as set forth in claim 1, wherein
the solar cell is arranged on the inside of the calendar wheel in the plan view seen in the direction.

### Claim 5 (depends on 4)

The electronic timepiece with a solar cell as set forth in claim 4, wherein
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.