Horology: time measuring systems or devices – Power supply details – Electrical
Reexamination Certificate
2000-04-03
2002-08-06
Miska, Vit (Department: 2859)
Horology: time measuring systems or devices
Power supply details
Electrical
C368S276000, C368S286000
Reexamination Certificate
active
06430111
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic timepiece having in the timepiece a secondary battery to be charged from outside the timepiece, and which has an electrostatic protection function for a charge terminal.
In recent years, electronic timepieces have been produced that have generator means such as solar generation means or thermoelectric generation means not requiring battery exchange. These timepieces have structurally provided therein a secondary battery so that generated power is stored in the secondary battery so that the timepiece need to be stopped even when power generation cannot be made. Here, if the secondary battery is small in capacity, there often occur cases in which storage electric power is used up. In order to prevent this, there is a tendency of using secondary batteries, large in capacity. However, where storage electric cower is used up it is difficult to charge the secondary battery up to a level necessary to operate the timepiece. There may be a case where the timepiece is rendered inoperable as the case may be. Due to this, a structure is used to directly charge the secondary battery from the outside thereby preventing such a disadvantage. Also, a timepiece has been put into products structured to charge the secondary battery inside the timepiece directly from the outside without having generator means.
In such a timepiece, because a charging electrode is extended to the outside, there is a possibility of applying an electric shock due to static electricity. A static electricity protection circuit is used to prevent a disadvantage due to electric shock.
The detailed circuit of a conventional static electricity protection circuit is explained using FIG.
1
. Also,
FIG. 2
shows a block diagram of an electronic timepiece having the conventional static electricity protection circuit. An input terminal
301
is connected to a first external electrode
101
through first connection means
114
of FIG.
2
. The input terminal
301
is connected to a resistance
302
. The resistance
302
has the other end connected to an output terminal
305
, an anode of a third diode
303
and a cathode of a fourth diode
304
. The third diode
303
has a cathode that is connected to a positive potential
112
on a positive side of storage means
109
. The fourth diode
304
has an anode connected to a reference potential
111
of a negative side of the storage means
109
. This reference potential
111
is extended outside the timepiece through the second external electrode
107
. The output terminal
305
is connected to an input part of a charge protection circuit
108
through the first diode
103
for reverse flow prevention. On the other hand, the voltage generated by a heat generator
104
is supplied to a booster circuit
105
through second connection means
113
. The electric power increased in voltage by the booster circuit
105
is supplied to the input part of the charge protection circuit
108
through the second diode
106
. The charge protection circuit
108
has an output connected with the storage means
109
to control the charge to the storage means
109
, preventing overcharge of the like. The electric power stored on the storage means
109
is supplied to a timepiece circuit
110
, and the timepiece circuit counts and displays a time.
If static electricity enters the input terminal
301
, it is reduced in voltage by the resistance
302
and further flows to the third diode
303
or fourth diode
304
thereby reducing over-voltage in a spike form. The effect of static electricity likely to occur at the output circuit
305
or the subsequent is reduced thus preventing breakdown or malfunction.
As charge electrodes an upper case and lower case of an exterior case are used. In this case, because insulation is provided between the upper case and the lower case, there is a case that the static electricity externally entered through the case flows to an electronic circuit inside the electronic timepiece without being immediately discharged to a human body. In order to reduce the effect of the static electricity on the timepiece circuit, the above static electricity protection circuit is used.
However, in the conventional static electricity protection circuit the effect is not sufficient in reducing the effort of static electricity. Although electrostatic breakdown can be prevented, circuit malfunction could not be prevented up to 6 KV of contact discharge in static electricity rating IEC1000-4-2 and 8 KV of in-air discharge.
In routine use, discharge occurs up to approximately 8 KV of contact discharge and 15 KV of in-air discharge as the operation may be. Accordingly, in this case, the conventional static electricity protection circuit could not have prevented malfunction of the timepiece circuit.
SUMMARY OF THE INVENTION
It is an object of the present invention to prevent malfunction, breakage or deterioration of an electronic timepiece due to high voltage of about 8 KV of contact discharge or 15 KV of in-air discharge in order not to cause trouble in routine use.
The electronic timepiece of the present invention is characterized in that, in an electronic timepiece having an exterior case structured by storage means, a conductor case and an insulation case, the conductor case is in a structure divided by the insulator case into a plurality wherein each conductor case is electrically in an insulation state. Furthermore, the conductor case is partly, structurally used as an electrode to charge to the storage means thereby enabling external energy of the electronic timepiece to the storage means. In these structures, in order to increase electrostatic withstand voltage, a pattern for discharging static electricity is further provided on a wiring board in a heat generator besides the usual static electricity protection circuit. Also, an air discharge layer is further provided between charge electrodes. This can prevent malfunction, breakage and deterioration of the timepiece circuit.
REFERENCES:
patent: 4106279 (1978-08-01), Martin et al.
patent: 4282597 (1981-08-01), Yenawine et al.
patent: 5280646 (1994-01-01), Koyama et al.
patent: 0608328 (1979-01-01), None
patent: 0846989 (1998-06-01), None
patent: 60078550 (1985-05-01), None
Adams & Wilks
Miska Vit
Seiko Instruments Inc.
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