Horology: time measuring systems or devices – Power supply details – Electrical
Reexamination Certificate
2000-10-03
2003-10-14
Miska, Vit (Department: 2859)
Horology: time measuring systems or devices
Power supply details
Electrical
C322S049000, C322S052000
Reexamination Certificate
active
06633511
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electronic controlling type mechanical timepiece in which the period of rotation of a generator is controlled by operating, a rotation controlling device by electrical power output from the generator operated by mechanical energy, used as a driving source, of a mechanical energy accumulating device, such as a mainspring.
BACKGROUND ART
There is known an electronic controlling type mechanical timepiece which controls the driving of a hand by controlling the period of rotation of a generator operated by a controlling device, such as an IC, by electrical power produced by rotation of the generator to which energy has been transmitted from a mechanical energy accumulating device, such as a mainspring, serving as an energy source.
According to the principle of driving the electronic controlling type mechanical timepiece, the mechanical energy accumulating device, such as a mainspring, is used as a mechanical energy source to drive a wheel train, and, instead of using a mechanical speed regulating mechanism, comprising an escape wheel and a timed annular balance that are characteristic component parts of a mechanical timepiece, a generator which is connected to the wheel train is used. The generator generates electrical power as a result of being subjected to rotational motion of the wheel train, and the electrical power generated thereby drives a controlling electronic circuit which is driven to generate a control signal. The period of rotation of the generator is controlled by the control signal from the electronic circuit in order to brake the wheel train and regulate the speed thereof. Therefore, in this structure, it is not necessary to use a battery for the driving source of the electronic circuit, and a precision as high as that provided by a battery-driven type electronic timepiece is provided.
A conventional electronic controlling type mechanical timepiece technology is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 8-5758 previously developed by the applicant.
FIG. 28
is a plan view of the timepiece disclosed in the document, and
FIG. 29
is a partial perspective view of a generator used in the timepiece.
The electronic controlling mechanical timepiece comprises a movement barrel including a mainspring, a barrel gear, a barrel arbor, and a barrel cover. The mainspring is a mechanical energy accumulating device, with the outside end thereof being secured to the barrel gear, and the inside end being secured to the barrel arbor. The barrel arbor is supported by a main plate and a wheel train bridge, and is secured by a square-hole screw
5
so as to be integrally rotatable with a ratchet wheel
4
. The ratchet wheel
4
engages a click
6
so as to allow the ratchet wheel
4
to rotate clockwise, but to prevent it from rotating counterclockwise.
The rotational power from the movement barrel
1
which incorporates the mainspring therein is increased in speed through a wheel train including a second wheel
7
, a third wheel
8
, a fourth wheel
9
, a fifth wheel
10
, and a sixth wheel
11
in order to be transmitted to a generator
20
.
The generator
20
has a structure similar to that of a driving stepping motor used in a conventional battery-driven type electronic timepiece, and comprises a rotor
12
, a stator
15
, and a coil block
16
.
In the rotor
12
, a rotor magnet
12
b
and a rotor inertial disk
12
c
are integrally mounted axially around a rotor pinion
12
a
connected to the sixth wheel
11
for rotation.
A stator coil
15
a
is wound at the outer periphery of the stator
15
. The stator
15
has a stator hole (a rotor placing hole or a rotor hole)
15
b
formed at an end thereof in order to rotatably accommodate the rotor magnet
12
b
, has a form defined by a pair of outside notches
15
c
formed at an interval of 180° at the outer periphery of the stator hole
15
b
so as to curve inward towards the hole
15
b
, and has its back end secured to the main plate (not shown) by a screw
21
.
The coil block
16
comprises a coil
16
b
wound upon a magnetic core
16
a
, and both ends thereof are placed upon both ends of the stator
15
and similarly secured together by a pair of screws
21
in order to form them into an integral structure.
PC permalloy is used as a material for constructing the stator
15
and the magnetic core
16
a
, and the stator coil
15
a
and the coil
16
b
are connected in series so that an output voltage in which each generated electrical power voltage is added is obtained.
Electrical power of the generator
20
obtained by the rotation of the rotor
12
is supplied to an electronic circuit including a crystal oscillator through a capacitor (not shown). The electronic circuit sends a signal for controlling the rotation of the rotor in accordance with a reference frequency and a detection of the rotation of the rotor
12
, as a result of which the wheel train rotates at a fixed speed in accordance with a braking force thereof.
This electronic controlling type mechanical timepiece does not require a motor because the mainspring is used as a power source for driving a hand, thereby reducing the number of component parts, and, thus, the cost. In addition, the generator
20
needs to generate only a slight amount of electrical energy to operate the electronic circuit, so that, for the mechanical energy from the mainspring, a slight torque is sufficient.
Oscillating weight timepieces including electrical power generating mechanisms are disclosed in, for example, Japanese Examined Patent Application Publication Nos. 7-38029 and 7-52229. In each of the oscillating weight timepieces, electrical power is generated by rotation of an oscillating weight, and the generated electrical power is accumulated in order to drive a stepping motor by the accumulated electrical power in order to move a hand. Compared to each of these oscillating weight timepieces, the conventional electronic controlling type mechanical timepiece only requires a small amount of electrical power, so that the cogging torque exerted onto the rotor
12
of the generator
20
is very small. More specifically, in each of the oscillating weight timepieces, the cogging torque exerted onto the rotor is usually of the order of 1.0×10
−6
N m, whereas, in the electronic controlling type mechanical timepiece, it is usually of the order of 4.0×10
−9
N m, so that, in the electronic controlling type mechanical timepiece, the torque is smaller by approximately a factor of 2 to 3.
Therefore, as in, for example, Japanese Unexamined Patent Application Publication Nos. 8-75873 and 9-203785, in each of the above-described oscillating weight timepieces, the cogging torque is reduced by forming, though in a different location, an inside notch.
In contrast, in the electronic controlling type mechanical timepiece, the cogging torque is extremely small compared to that in each of the oscillating w eight timepieces, so that taking measures to further reduce the cogging torque was not considered.
From the results of assiduous research and development carried out to put the electronic controlling type mechanical timepiece into practical use, the present applicant has discovered the electronic controlling type mechanical timepiece has the following problems which do not arise in the oscillating weight timepieces.
In each of the oscillating weight timepieces, electromotive power of the generator operated by the oscillating weight causes the capacitor to be charged, and the stepping motor driven by the electrical power from the capacitor causes a hand to move. Therefore, even if the generator is temporarily stopped by an external disturbance, the hand continues to move without stopping as long as the capacitor does not discharge.
In contrast to this, in the electronic controlling type mechanical timepiece, a hand is driven in connection with the generator
20
, so that, when the generator
20
stops, the hand stops moving immediately, resulting in the problem that an error occurs in the indicatio
Matsuzawa Kinya
Moteki Masatoshi
Sekino Hirokazu
Gabrik Michael T.
Miska Vit
Seiko Epson Corporation
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