Electronic watch

Details Electronic watch Electronic watch

1998-10-21

2001-02-06

Roskoski, Bernard (Department: 2859)

Horology: time measuring systems or devices

Arbor and pinion details

C368S324000

Reexamination Certificate

active

06183125

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an electronic watch including a so-called automatic winding dynamo, and more particularly to a technology for improving the structure of such an electronic watch to achieve a reduction in thickness.
BACKGROUND OF THE INVENTION
In a so-called electronic watch using a crystal oscillator or the like as a time base, as shown in
FIG. 1
, a power supply section
10
is made up of a small-sized dynamo
20
and a secondary power supply
30
, and a stepping motor
40
is driven by power supplied from the power supply section
10
. A watch wheel train
50
is operatively connected to a motor rotor
42
of the stepping motor
40
so that, for example, a second hand
161
attached to a second wheel
52
is intermittently rotated in steps of 6 for each second.
On the other hand, the small-sized dynamo
20
comprises a dynamo rotor
21
rotated by torque transmitted to it, a dynamo stator
22
disposed in surrounding relation to the dynamo rotor
21
, and a dynamo coil
23
wound over a magnetic core
24
making up a magnetic circuit in cooperation with the dynamo stator
22
and the dynamo rotor
21
. A dynamo wheel train
60
for transmitting rotation of an oscillating weight
25
while speeding up the rotation is operatively connected to the dynamo rotor
21
.
In the field of electronic watches with hands, there is a strong demand for a reduction in thickness even in the above-mentioned type having a small-sized dynamo. However, such a demand for a reduction in thickness cannot be satisfied simply by reducing the size or thickness of various parts, e.g., the oscillating weight
25
as one component of the small-sized dynamo. For example, if the thickness of the oscillating weight
25
is reduced, weight unbalance of the oscillating weight
25
in the angular direction would be diminished and the oscillating-weight
25
would be hard to rotate at a high speed. Also, because necessary parts are mounted on a circuit board
31
constituting a circuit section, the circuit section cannot be further reduced in size and thickness. If it is nonetheless attempted to reduce a space in which the circuit section is installed, there would occur a risk that electronic parts and so forth may interfere with gears of the dynamo wheel train
60
and the watch wheel train
50
.
A rotational shaft of the dynamo rotor
21
and a rotational shaft of the dynamo wheel train
60
are each often supported by a small and simple bearing formed of a hole jewel. In the bearing structure using a hole jewel, however, a lubricant applied to the rotational shaft tends to scatter to the surroundings upon rotation of the rotational shaft. If the scattered lubricant adheres to the watch wheel train
50
, the lubricant may cause abnormal motion in driving the hands, such as stop or delay of any of gears, due to its viscosity. This raises a problem in conventional electronic watches with hands in that the parts cannot be arranged in closer relation and hence the thickness of the watch cannot be reduced.
Further, in the conventional electronic watches with hands, as shown in
FIG. 11
, one of the gears of the dynamo wheel train which tends to be easily subject to lateral pressure, such as a dynamo rotor transmitting wheel
62
A (see FIG.
1
), is sometimes supported at its rotational shaft
20
A by a ball bearing
28
A. The ball bearing
28
A comprises a plurality of balls
281
A arranged around the rotational shaft
620
A of the dynamo rotor transmitting wheel
62
A, a ring-shaped frame piece
282
A holding the balls
281
A, and a retainer piece
283
A positioned adjacent the frame piece
282
A to cooperate with it to prevent the balls
281
A from slipping off. The balls
281
A are held in contact with the rotational shaft
620
A to restrict a lateral inclination of the rotational shaft
620
A. Also, the rotational shaft
620
A has a stepped portion
626
A formed around it, and the stepped portion
626
A abuts against the retainer piece
283
A to restrict the position of the rotational shaft
620
A in the axial direction.
However, the bearing structure shown in
FIG. 11
has a problem that large friction resistance generates between the stepped portion
626
A and the retainer piece
283
A when the rotational shaft
620
A is rotated. Generation of large friction resistance means that wasteful excessive force is required to rotate the rotational shaft
620
A, and that the stepped portion
626
A or the retainer piece
283
A is severely worn away. Thus, there is a need for a novel bearing structure capable of solving the above-stated problems. However, even a bearing structure which has succeeded in solving the above-stated problems cannot be practically adopted if it requires a larger space, because such a bearing structure prevents a reduction in thickness of electronic watches with hands.
In view of the problems stated above, an object of the present invention is to provide a construction of an electronic watch with a built-in dynamo, which can improve structures of parts themselves arranged inside the watch and layout of the parts, and can reduce a total thickness of the electronic watch.
SUMMARY OF THE INVENTION
To achieve the above object, according to the present invention, an electronic watch having a base on which are mounted a dynamo including a dynamo wheel train for transmitting external force to a dynamo rotor, a secondary power supply for storing electric energy generated by the dynamo, a circuit section including a driving circuit supplied with power from the secondary power supply, a stepping motor driven by the driving circuit, and a watch wheel train for transmitting torque from the stepping motor to a time indicating member, is constructed as follows.
According to a first aspect of the present invention, at least one of a rotational shaft of the dynamo rotor and a rotational shaft of the dynamo wheel train is supported by a bearing portion comprised of a hole jewel portion supporting an axial end of the rotational shaft, and a ring-shaped cap portion covering one end surface of the hole jewel portion from the outer side to define a lubricant holding annular slot between the cap portion and an outer circumferential surface of the rotational shaft.
In the present invention, even under rotation of the rotational shaft, a lubricant applied to between the rotational shaft and the hole jewel portion is kept in the lubricant holding annular slot defined by the outer circumferential surface of the rotational shaft itself, the cap portion and the hole jewel, and is prevented from scattering to the surroundings. Accordingly, gaps between adjacent parts can be narrowed and the thickness of the electronic watch can be reduced.
In the present invention, preferably, the hole jewel portion and the cap portion make up a bearing portion for the rotational shaft of the dynamo rotor. The lubricant tends to scatter most easily from the bearing portion of the dynamo rotor which is rotated at a maximum speed in the watch wheel train and the dynamo wheel train. It is therefore preferred that the above bearing structure is provided for the rotational shaft of the dynamo rotor.
In the present invention, the hole jewel portion and the cap portion may be constructed by separate parts from each other. In this case, preferably, a gap is defined between the cap portion and the one end surface of the hole jewel portion covered by the cap portion. The presence of such a gap is advantageous in that when an assembly of the hole jewel portion and the cap portion fitted to each other is subject to surface treatment for preventing the lubricant from spilling out, a treatment solution can smoothly enter a space between the hole jewel portion and the cap portion, enabling the surface treatment to be reliably conducted all over the surfaces including the space between the hole jewel portion and the cap portion. Here, a size of the gap can be determined by the depth of the fit which results when the hole jewel portion is fitted into the cap portion.
In the present invention, the hole jewel porti

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