Electronic timepiece with internal antenna
An electronic timepiece with internal antenna maintains sufficiently high reception performance of circularly polarized waves even when having a metal external case. The timepiece has a cylindrical case; a crystal that covers the opening on the face side of the case; a drive mechanism that arranged inside the case; a metal antenna; and a dielectric. The antenna houses the drive mechanism and has a cylindrical side part, a bottom part that covers the opening on the back side of the side part, and an antenna electrode that contacts the inside of the side part. The back cover covers the back side of the case and is also the bottom part. The dielectric extends circumferentially to the side part, and contacts the antenna electrode in the face-back cover direction. A slot extending circumferentially is formed in the antenna electrode. Part or all of the slot is covered by the dielectric.
1. An electronic timepiece with internal antenna, comprising:
a cylindrical external case;
a crystal that covers one of the two openings of the external case;
a drive mechanism that drives a hand inside the external case;
an antenna that has a cylindrical side part made of metal, a metal bottom part that covers one of the two openings of the side part, and a metal top part that extends transversely to the center axis of the side part inside the external case, and contacts the inside surface of the side part,
holds the drive mechanism between the bottom part and the top part, and has the top part disposed between the drive mechanism and the crystal; and
an annular dielectric that extends circumferentially to the side part and contacts the top part in the axial direction of the side part;
wherein the external case has a metal part that is made of metal,
the bottom part is a back cover that covers the other of the two openings of the external case,
the top part has a slot part that extends circumferentially to the side part and contacts the dielectric,
a slot that extends circumferentially to the side part is formed in the slot part, and
the dielectric covers part or all of the slot in the axial direction of the side part.
2. The electronic timepiece with internal antenna described in claim 1 , wherein:
the metal part includes part or all of the side part.
3. The electronic timepiece with internal antenna described in claim 1 , wherein:
the electronic timepiece further includes a dial disposed between the hand and the top part; and
the slot is disposed between the dial and the side part when seen from a direction perpendicular to the crystal.
4. The electronic timepiece with internal antenna described in claim 1 , wherein:
the hand rotates on a center shaft;
the top part has a center part surround by the slot part; and
a hole through which the center shaft passes is open in the center part.
5. The electronic timepiece with internal antenna described in claim 4 , further comprising:
an image display unit that displays an image and is disposed between the top part and the bottom part; and
a window for viewing the image is opened in the center part.
6. The electronic timepiece with internal antenna described in claim 1 , further comprising:
a photovoltaic conversion panel that extends transversely to the center axis of the side part, and converts light energy to electrical energy, and
is disposed between the top part and the hand inside the slot part when seen from the axial direction of the side part.
7. The electronic timepiece with internal antenna described in claim 1 , wherein:
the shape of the slot is a C-shape; and
the antenna has a power supply node at a specific position referenced to an end of the slot.