Horology: time measuring systems or devices – Power supply details
Reexamination Certificate
2000-11-02
2003-02-18
Miska, Vit (Department: 2841)
Horology: time measuring systems or devices
Power supply details
C368S204000
Reexamination Certificate
active
06522603
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a charging device for an electronic timepiece having a generator for receiving at least one type of external energy and converting the external energy into electric energy and a charge storer for storing the electric energy generated by the generator. The present invention further relates to an electronic timepiece using such a charging device, and a method for controlling the charging device.
2. Description of the Related Art
A small-sized electronic timepiece such as a wristwatch has a time-keeping circuit for measuring time and a timepiece driving circuit including a driving circuit for driving a motor which is coupled to a hand moving mechanism, i.e., a mechanism to move hands of the timepiece. Electronic timepieces having a generator therein have been realized in the art, which can operate without having to replace a used battery.
In these electronic timepieces, the electric power generated by the generator can be once charged into a secondary power source such as a capacitor. Therefore, when no electric power is being generated, time display is performed by the electric power which is discharged from the secondary power source. This enables the timepiece to stably operate over a long period of time without a battery.
In view of the labor and time for replacing a used battery or the problems associated with the disposal of used batteries, it is expected that more electronic timepieces will be provided with a generator in the future.
Generators which are provided in a timepiece such as a wristwatch include a solar battery which converts incident light into electric energy, a power generation system which converts kinetic energy of the movement of the user's arm into electric energy, etc.
These generators are quite desirable in that they can utilize energy around the user by converting it into electric energy. However, the available energy density is small, and the energy cannot be obtained continuously. Therefore, power is not generated continuously. During the non-power-generation periods (i.e., when the generator is in an inoperative state), the electronic timepiece is operated by the electric power which has been stored in the secondary power source.
In the case of an electronic device with a solar battery installed, for example, no electric power is generated by the solar battery in the nighttime. In such an electronic device with a solar battery installed, a charge storer discharges to operate a processing device. Therefore, it is desired to increase the storage capacity of the charge storer so as to accommodate situations where no electric power is generated by the power generation system. However, an increase in the storage capacity of the charge storer also increases the time required to charge the capacitor device. As a result, once the capacitor device is completely discharged off, it then takes a long time for the capacitor device to be charged to a predetermined voltage sufficient to operate the processing device. Thus, once a device employing a solar battery stops operating, for example, it will take some time to start up the device even after the device is placed back into an environment where light is incident upon the solar battery and the power generation has been resumed.
A number of circuits have been devised in the art to shorten the processing device start-up time in such situations.
An example of such circuits is shown in
FIG. 8
which is a block diagram illustrating portable electronic equipment (an electronic timepiece) having a solar battery as described in Japanese Patent Provisional Publication No. 9-264971, entitled “Power Control Device, Power Generation Device and Electronic Equipment”.
In
FIG. 8
, the electronic timepiece includes a solar battery
501
, a capacitor device
513
, and a power control section
520
.
The solar battery
501
converts energy of the sunlight into electric power.
The capacitor device
513
stores the electric power from the solar battery
501
.
The power control section
520
supplies the electric power from the solar battery
501
to the large-capacity capacitor device
513
and to a processing device
509
such as a time-keeping device.
The capacitor device
513
will now be described in detail.
The capacitor device
513
includes a capacitor
502
, diodes
517
,
521
,
522
and
529
, switches
518
,
523
and
524
, a limit switch
519
, and a control circuit
530
.
The capacitor
502
is a large-capacity capacitor such as an electric doublelayer capacitor.
The switch
523
is coupled between the ground power rail (which in the present case is used as the reference high voltage VDD) and the anode of diode
522
. When switch
523
is actuated (i.e. is closed) it forms a bypass current path around diode
521
. Diodes
521
and
522
are coupled end-to-end such that when switch
523
is not actuated (i.e. is opened), diodes
521
and
522
are effectively serially connected with each other. In the electronic timepiece illustrated in
FIG. 8
, the reference high voltage VDD is the ground voltage power rail (reference voltage), and the VSS line is the relative low voltage. To emphasize that VDD is implemented by the ground power rail, the term “ground voltage VDD” is at times used to refer to the reference high source, i.e. high side, of the circuit.
The switch
524
is coupled between the VDD voltage and the cathode of diode
522
. When switch
524
is actuated (i.e. is closed), it forms a bypass current path around both of the diodes
521
and
522
.
The diode
529
is provided between the solar battery
501
and one of the terminals of the capacitor
502
which is on the VSS voltage (low voltage) side. The diode
529
functions as a reverse current flow prevention diode. Specifically, the diode
529
is operative to ensure that a voltage which is discharged from the capacitor
502
while no power is being generated from the solar battery
501
is not applied to the solar battery
501
.
The diode
517
is operative to ensure that a current does not flow in the reverse direction from an auxiliary capacitor device
516
including a small-capacity capacitor
503
to the solar battery
501
.
The switch
518
is a switch provided for controlling a discharge from the capacitor device
513
into the auxiliary capacitor device
516
.
The limit switch
519
short-circuits the high voltage side VDD and the low voltage side VSS with each other when the voltage supplied from the solar battery
501
is too high. In this way, it is possible to prevent the capacitor device
513
from being overcharged so that a high voltage is not applied to the processing device
509
, etc.
The control circuit
530
monitors various voltages in the power control section
520
and controls the switches. The control circuit
530
detects a voltage VSCP on the high voltage side of the capacitor device
513
, a voltage VSCN on the low voltage side of the capacitor device
513
, the voltage VSS which is supplied to the processing device
509
, etc.
Based on the detection results, the control circuit
530
outputs control signals for controlling the switch
523
and the switch
524
, respectively. The control circuit
530
also outputs a control signal for controlling the switch
518
(which is provided for controlling the discharge from the capacitor device
513
into the auxiliary capacitor device
516
), and a control signal for controlling the limit switch
519
.
With the configuration as described above, a charge voltage VSC of the capacitor device
513
is equal to the difference between the terminal voltages thereof, i.e., between the high potential side voltage VSCP and the low potential side voltage VSCN. However, when light is illuminated onto the solar battery
501
while substantially no electric charge is stored in the capacitor device
513
and the charge voltage VSC is substantially 0 V, the switches
523
and
524
are turned OFF.
Therefore, the electric power supplied from the solar battery
501
is dropped by a forward bias voltage of the d
Iijima Yoshitaka
Miyahara Fumiaki
Nakamiya Shinji
Goodwin Jeanne Marguerite
Haro Rosalio
Miska Vit
Seiko Epson Corporation
LandOfFree
Charging device for electronic timepiece, electronic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Charging device for electronic timepiece, electronic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Charging device for electronic timepiece, electronic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3181331