Thermoelectrically operated timepiece

Abstract: For efficient operation of a thermoelectrically operated timepiece, heat is transferred into and out of a thermoelectric device by mounting a thermally conductive plate (4) on the thermal energy output side (3b) of the thermoelectric device and placing the plate in direct contact with a heat-dissipating frame (5) made of a material having a high thermal conductivity. The heat-dissipating frame is placed on the top surface of a case body (9). The thermally conductive plate uses a material having a high thermal conductivity. As a result, the efficiency of the thermoelectric conversion can be improved. Also, heat can be dissipated efficiently.

Description: The present invention relates to thermoelectrically operated timepiece. The cross-sectional configuration of a prior art thermoelectrically operated timepiece is shown in Fig. 4 and disclosed, for example, in Japanese Unexamined Patent No. 13279/1990. In Fig. 4, a movement 30 is thermally insulated from a cold bezel 31 and from a hot casing bottom portion 32 by a frame portion 37 via a metal ring 38. Plastic rings 33 and 34 support the movement 30 and thermally insulate a thermoelectric generator 36 located between the casing bottom portion 32 and the cold metal ring 35. In such prior art thermoelectrically operated timepiece, heat is dissipated from the cold bezel 31 and from the cold metal ring 35 via the metal ring 38 on the cold side of the thermoelectric generator. Therefore, the frame portion 37 tries to provide heat insulation between the casing bottom and the metal ring, but heat is transmitted to the metal ring 38 located near the thermoelectric generator. The result is that the efficiency of the heat dissipation is low. FR 2425664A describes a wrist-watch comprising a thermoelectric generator. Summary of the Invention Accordingly, it is an object of the present invention to solve the foregoing problem. The present invention provides a thermoelectrically operated timepiece using electric power generated by a thermoelectric converter as an energy source, said timepiece comprising: a heat input means for absorbing heat from a human body with which the timepiece is in contact; a thermally conductive resilient or elastic member for conducting heat absorbed by the heat input means to a thermal energy input side of a thermoelectric generator means; characterised in that a thermally conductive means comprising a plate is mounted in contact with a heat output portion of the thermoelectric generator means, and in contact with a heat output means for exhausting heat, said heat output means comprising a heat-dissipating frame of the timepiece case, and said heat output means and said heat input means being spaced from each other. With the invention, a thermally conductive plate made of a material having a high thermal conductivity is mounted on the output side of a thermoelectric device from which thermal energy is taken. This thermally conductive plate is placed on the top surface of a case body and in direct contact with a heat-dissipating frame made of a material having a high thermal conductivity. Thus, heat can go into and out of the thermoelectric generator with high efficiency. In the structure according to this invention, a heat input means absorbs heat from a human body with which this structure is in contact, a thermally conductive elastic member conducts heat absorbed by the heat input means to a thermal energy input side of a thermoelectric generator means, and a thermally conductive means conducts heat between a heat energy output side of the thermoelectric generator means and a heat output means. The heat output means and the heat input means are spaced widely from each other. Brief Description of the Drawings Fig. 1 is a functional block diagram of a thermoelectrically operated timepiece in accordance with the present invention; Fig. 2 is a typical schematic illustrating the principle of operation of a thermoelectrically operated timepiece in accordance with the invention; Fig. 3 is a cross-sectional view showing die configuration of a thermoelectrically operated timepiece in accordance with the invention; Fig. 4 is a cross-sectional view of the prior art thermoelectrically operated timepiece; and Fig. 5 is a cross-sectional view showing a modification of the thermoelectrically operated timepiece in accordance with the invention. Detailed Description of the Preferred Embodiments Fig. 1 is a functional block diagram of a thermoelectrically operated timepiece in accordance with the present invention. In Fig. 1, a heat input means 54 absorbs heat from a human body with which the timepiece is in contact. A thermally conductive elastic or resilient member 53 conducts the heat absorbed by the heat input means 54 to the heat energy input side of a thermoelectric generator means 52. A thermally conductive means 51 provides heat conduction between the thermal energy output side of the thermoelectric generator means 52 and a heat output means 50. Fig. 2 is a schematic showing the principle of operation of a thermoelectrically operated timepiece in accordance with the present invention. In Fig. 2, the timepiece comprises a thermoelectric generator means 63 for receiving heat from a human body with which the timepiece is contacted and converting the heat into electricity, an electricity storage means 62 for storing the electricity converted by the thermoelectric generator means 63, an operation control means 61 powered by the electric power stored in the electricity storage means 62, and an indicating means 60 for displaying the time or the like under control of the operation control means 61. Fig. 3 is a cross-sectional view showing the configuration of a thermoelectrically operated timepiece in accordance with the present invention. In Fig. 3, there is provided a rear cover I that is a heat input means (54). A rear cover packing 10 is held between the rear cover 1 and a case body 9 made of a thermoplastic resin, for example, that is effective in providing thermal insulation. A thermally conductive spring 2 that is a thermally conductive elastic or resilient member (53) is made of a material having a high thermal conductivity such as aluminium or copper. One end of the thermally conductive spring 2 is in contact with the rear cover 1, while the other end is in contact with the heat input side portion 3a of a thermoelectric device 3 that is a thermoelectric generator means (52). The spring is held as shown by a main plate 12 made of a thermoplastic resin that is effective in providing heat insulation. A heat output side portion 3b, or the other side of the thermoelectric device 3, is in contact with a thermally conductive plate 4 having a guide pin portion 4a on its outer surface. The thermally conductive plate 4 is a thermally conductive means (51) that guides a dial 6. A thermal ray-reflecting coating (not shown) is formed on the surface of the dial 6. A heat-dissipating frame 5 is formed on the case body 9 by insert moulding from a material having a high thermal conductivity such as aluminium or copper. A heat-dissipating frame 5 that is a heat output means (50) and treated with an anticorrosive is mounted on the case body 9. The heat-dissipating frame 5 holds a glass 7 via a glass packing 8, and is in contact with the guide pin portion 4a of the thermally conductive plate 4. A printed circuit board 11 is in contact with one side (e.g., the heat output portion 3b) of the thermoelectric device 3 by a wire 11a The printed circuit board 11 (61) is electrically connected with a circuit block 15 (61) fixed to the main plate 12. Electric power generated by the thermoelectric device 3 (63) is stored (62) in a secondary battery 14 by the printed circuit board 11 under control of an electricity storage control circuit (not shown). The circuit block 15 powered by the stored electric power activates a driving motor (not shown) to operate and control a hand wheel train 17 (60) including a fourth wheel and pinion 17a, a second wheel and pinion 17b, and a hour wheel 17c that are held by a wheel train bridge 16 and the main plate 12. Hands comprising a second hand 18a, a minute hand 18b, and a hour hand 18c are mounted to the hand wheel train 17 to display the time. The secondary battery 14, the circuit block 15, and so on are made stationary by a holder 13. A space effective in providing thermal insulation between the rear cover 1 is secured. Fig. 5 is a cross-sectional view showing a modification of the embodiment shown in Figure 3 of a thermoelectrically operated timepiece in accordance with the present invention. In Fig. 5, the case body 9 made of a thermoplastic resin has an inclined surface portion 9a permitting a drive or interference fit. The heat-dissipating frame 5 has an inner inclined surface portion 5a that cooperates with the inclined surface portion 9a of the case body 9 to enable mounting with an interference. This embodiment is similar to Embodiment 1 in other respects. As described, the present invention comprises a heat input means for absorbing heat from a human body with which this structure is in contact, a thermally conductive elastic member for conducting heat absorbed by the heat input means to a thermal energy input side of a thermoelectric generator means, and a thermally conductive means for conducting heat between a thermal energy output side of the thermoelectric generator means and a heat output means. The heat output means and the heat input means are spaced widely from each other. Heat can be transferred into and out of the thermoelectric device efficiently. As a result, the efficiency of the thermoelectric conversion can be improved. The aforegoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.

Claims: A thermoelectrically operated timepiece using electric power generated by a thermoelectric converter (3, 52, 63) as an energy source, said timepiece comprising: a heat input means (1, 54) for absorbing heat from a human body with which the timepiece is in contact; a thermally conductive resilient or elastic member (2, 53) for conducting heat absorbed by the heat input means to a thermal energy input side (3a) of a thermoelectric generator means (3, 52, 63); characterised in that a thermally conductive means (4,51) comprising a plate (4) is mounted in contact with a heat output portion (3b) of the thermoelectric generator means, and in contact with a heat output means (5, 50) for exhausting heat, said heat output means comprising a heat-dissipating frame (5) of the timepiece case, and said heat output means (50) and said heat input means (54) being spaced from each other. A timepiece according to claim 1, wherein said frame (5) is formed by insert moulding a material of high thermal conductivity. A timepiece according to claim 1 or 2, wherein said frame is secured to the case by making an interference fit (5a,9a) with the case body (9). A timepiece according to any preceding claim, wherein the thermally conductive means (4, 51) includes an upstanding pin (4a) for positioning a dial (6) of the timepiece. A timepiece according to any preceding claim, wherein the thermally conductive resilient or elastic member (2, 53) comprises a spring (2) of a material such as aluminium or copper. A timepiece according to any preceding claim, wherein the heat input means comprises a rear cover (1) of the case. A timepiece according to any preceding claim, wherein the dial (6) of the timepiece has a surface coating to reflect thermal radiation.

Inventors: KAWATA MASAYUKI, KAWATA, MASAYUKI
Applicants: SEIKO INSTR INC, SEIKO INSTRUMENTS INC.
Application year: 1997
Main classification: G04C10
IPC codes: G04C10, H02N11, G04G19