JP2001103672A - Electronic equipment and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of a secondary battery by preventing the voltage of the secondary battery from exceeding an allowable voltage caused by the internal resistance of the secondary battery when a charge current rapidly changes. SOLUTION: Even if the voltage of a secondary battery is near an allowable voltage or even if a charge current rapidly changes based on the consumption current of a load and the size of the load, the charge current due to charging following the change is controlled so that the voltage of the secondary battery does not exceed the allowable voltage, thus suppressing the deterioration of the secondary battery and hence extending the life of electronic equipment where the secondary battery is mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device and a control method of the electronic device, and more particularly to an electronic device and an electronic device capable of charging a built-in secondary battery for supplying a driving power. It relates to a control method.

[0002]

2. Description of the Related Art In recent years, small portable electronic devices (= charged electronic devices) such as portable terminals and electronic timepieces are housed in chargers called stations, and the portable electronic devices are configured to be charged. It has been known. In such a configuration, a lithium ion secondary battery is provided in the small portable electronic device as a power storage device for storing charged electric energy. This lithium ion secondary battery has features such as high voltage, high energy density, and relatively low self-discharge, and particularly small portable electronic devices (for example, a mobile phone, a camera-integrated video, Tape recorders, notebook personal computers, etc.).

In a lithium ion secondary battery, when a voltage higher than a so-called allowable voltage is applied, dendrite (dendritic crystals) precipitates, causing an internal short circuit phenomenon and shortening the life of the battery. Therefore, as a general charging method, constant current charging is performed until the charging voltage of the lithium ion secondary battery reaches the allowable voltage, and constant voltage charging is performed after the charging voltage reaches the allowable voltage (details). About Japanese Patent Application Laid-Open No. 5-111184). When charging between the small portable electronic device and the charger, the battery voltage of the lithium ion secondary battery should not exceed the allowable voltage.
A limiter circuit for limiting a rise in battery voltage was provided.

[0004]

FIG. 12 shows a circuit diagram of a power supply system of a conventional electronic timepiece (= small electronic equipment). The electronic timepiece 500 can be roughly classified into a timepiece coil 510 functioning as an electromagnetic coupling coil used for charging, a secondary battery 520 functioning as a power storage unit, a load 530 connected to the secondary battery 520, and a secondary battery 520. A limiter circuit 54 that electrically disconnects the secondary battery 520 from the clock side coil 510 when the voltage of the battery 520 becomes equal to or higher than a predetermined limit voltage.
0 and a backflow prevention diode 550 for preventing backflow of the charging current from the watch side coil 510. The limiter circuit 540 includes a comparator 541 including an operational amplifier that sets a limit control signal to an “H” level when the voltage of the secondary battery 520 exceeds a reference voltage Vreg corresponding to a predetermined allowable voltage. When the output limit control signal is at the “H” level, the output is turned on, and a closed loop is formed between the output terminals of the clock side coil 510 via the current limiting resistor 542 so that the secondary battery 520 is connected to the clock side coil 510. And a transistor switch 543 that is electrically disconnected from the power supply.

In this case, the input current input through the clock side coil 510 is represented by IIN and the limiter circuit 540.
The bypass current flowing through the diode and the backflow prevention diode 5
Id is the current flowing through 50, Ij is the charging current, and 530 is the load.
The following relational expression is obtained assuming that the consumption current flowing through is IL. Id = Ij + IL IIN = IS + Id By modifying these equations, Ij = Id-IL = IIN- (IS + IL) is obtained. Here, assuming that the internal resistance of the secondary battery 520 is r, the charging voltage of the secondary battery rises by Ij · r [V] more than the actual charging voltage.

If the response speed of the comparator 541 is sufficiently fast, it is possible to control the transistor switch 543 to flow the bypass current IS so that the battery voltage VD does not exceed the allowable voltage Vreg. However,
If the response speed of the comparator 541 is not very fast, if the change in the charging current Ij is too fast, it is impossible to follow the change in the battery voltage VD, and VD> Vreg, and there is a possibility that the allowable voltage of the secondary battery 520 will be exceeded. Occurs. More specifically, as shown in FIG. 13A, the consumption current IL of the load 530 becomes 10 at time t0.
When [mA] changes from [mA] to 0.1 [mA], FIG.
As shown in (b), the charging current Ij has an initial current of 5 [m
A], 14.9 [mA], and the limiter circuit 540 due to the response time TOP of the comparator 541.
The timing at which the device actually operates is time t1, and FIG.
As shown in (c), the battery voltage VD exceeds the allowable voltage Vreg during the period from time t0 to time t1. Therefore, when the secondary battery 520, especially the secondary battery 520 is a lithium ion secondary battery, there is a problem that the life is shortened. Therefore, an object of the present invention is to prevent the voltage of the secondary battery from exceeding the allowable voltage due to the internal resistance of the secondary battery when the charging current changes abruptly, and to prevent the deterioration of the secondary battery. An object of the present invention is to provide an electronic device and a control method of the electronic device that can prevent the electronic device.

[0007]

According to a first aspect of the present invention, there is provided a power storage device which is capable of being charged externally and which is set so that a charging voltage does not exceed a predetermined allowable voltage. In an electronic device having a device and a load device driven by electric power stored in the power storage device, a charging current is bypassed by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage. Charging current bypass means, current consumption detecting means for detecting current consumption in the load device, and forced bypass means for forcibly bypassing the charging current via the charging current bypass means based on the magnitude of the current consumption. And, it is characterized by having.

According to a second aspect of the present invention, a power storage device that can be charged from the outside and is set so that a charging voltage does not exceed a predetermined allowable voltage, and is driven by electric power stored in the power storage device A charging current bypass unit that bypasses a charging current by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage; and a magnitude of a load in the load device. Heavy load detecting means for detecting the load, and forced bypass means for forcibly bypassing the charging current via the charging current bypass means based on the magnitude of the load.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the forced bypass means comprises:
A resistance value control means for forcibly reducing the flow path resistance value of the charging current in the charging current bypass means is provided.

According to a fourth aspect of the present invention, in the configuration of the first or second aspect, the charging current bypass means includes a resistance element, a backflow prevention element, and the resistance element connected via the backflow prevention element. First switch means connected in parallel to the power storage device, wherein the forced bypass means comprises:
A second switch for controlling the first switch and forcibly connecting the resistance element to the power storage device in parallel;
And second switch control means for controlling the second switch means.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the first switch means is a comparator, and the resistance element is a transistor whose comparator output is input to a control terminal as a control signal. Preferably, the second switch means is a transistor that outputs a control signal to the control terminal for forcibly turning the transistor on.

According to a sixth aspect of the present invention, in the configuration of the first or second aspect, the charging current bypass means charges a variable resistance means having a variable resistance value and a resistance value of the variable resistance means. Resistance value control means for controlling based on current or the allowable voltage.

According to a seventh aspect of the present invention, in the configuration of the first or second aspect, after the charging current is forcibly bypassed through the charging current bypass means,
It is characterized by comprising a return speed suppressing means for reducing the return speed when returning.

[0014] According to the eighth aspect of the present invention, a power storage device that can be charged from the outside and is set so that a charging voltage does not exceed a predetermined allowable voltage, and is driven by electric power stored in the power storage device In the control method of the electronic device having a load device, a charging current bypass step of bypassing the charging current by a predetermined amount so that the charging voltage in the charging device does not exceed the allowable voltage,
A current consumption detecting step for detecting a current consumption in the load device, and a forced bypass step for forcibly bypassing the charging current based on the magnitude of the current consumption are provided.

According to a ninth aspect of the present invention, a power storage device that can be charged from the outside and is set so that a charging voltage does not exceed a predetermined allowable voltage, and is driven by power stored in the power storage device In the control method of the electronic device having a load device, a charging current bypass step of bypassing the charging current by a predetermined amount so that the charging voltage in the charging device does not exceed the allowable voltage,
The method further includes a heavy load detecting step of detecting a magnitude of a load in the load device, and a forced bypass step of forcibly bypassing the charging current based on the magnitude of the load.

According to a tenth aspect of the present invention, in the configuration of the eighth or ninth aspect, the forcible bypass step forcibly reduces the resistance value of the flow path of the charging current for bypassing the charging current. It is characterized by comprising a resistance value control step of decreasing the resistance value.

According to an eleventh aspect of the present invention, in the electronic device control method according to the eighth or ninth aspect, a flow path of the charging current for bypassing the charging current includes a resistance element and a backflow prevention. An element and a first switch that connects the resistance element in parallel to the power storage device via the backflow prevention element, and the forcible bypass process forcibly controls the first switch to control the first switch. Comprising a forced switch control step of connecting a resistance element to the power storage device in parallel,
It is characterized by:

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. [1] First Embodiment First, a first embodiment of the present invention will be described. In addition,
In the present embodiment, an electronic timepiece will be described as an example of the electronic device, and a station that charges the electronic timepiece and performs communication with the electronic timepiece will be described as an example. However, the present invention is not limited to these stations. Absent. [1.1] Mechanical Configuration FIG. 1 is a plan view of a station and an electronic timepiece according to the embodiment. As shown in FIG. 1, the electronic timepiece 200
When charging, data transfer, or the like is performed, it is accommodated in the recess 101 of the station 100. Since the recess 101 is formed in a slightly larger shape than the main body 201 and the band 202 of the electronic timepiece 200, the timepiece main body 201 is accommodated in a state positioned with respect to the station 100. In addition, the station 100, the charging and start button 103 ₁ for instructing the start of charging, with various input unit such as a transfer start button 103 ₂ for instructing the start of data transfer, for performing various displays Display unit 10
4 are provided. Note that the electronic timepiece 200 according to the present embodiment is worn on the user's arm in a normal use state, and it is needless to say that the date and time and the like are displayed on the display unit 204. It is configured to detect and store biological information such as heart rate at regular intervals.

FIG. 2 is a sectional view taken along line AA in FIG. As shown in the figure, a watch side coil 210 for data transfer and charging is provided on a lower back cover 212 of a main body 201 of an electronic timepiece via a cover glass 211. Further, the watch main body 201 is provided with a circuit board 221 connected to the secondary battery 220, the watch side coil 210, and the like. On the other hand, in the recess 101 of the station 100, a station-side coil 110 is provided via a cover glass 111 at a position facing the clock-side coil 210. The station 100 includes a coil 110, a charge start button 103 ₁ , a transfer start button 10
3 _2, the display unit 104, a circuit board 121 that is connected to such primary source (not shown) is provided. in this way,
In a state where the electronic timepiece 200 is housed in the station 100, the station-side coil 110 and the watch-side coil 210 are not physically in contact with each other due to the cover glasses 111 and 211. In effect, they are in a connected state. Further, the station-side coil 110 and the clock-side coil 210 do not have a magnetic core for reasons such as avoiding magnetization of the clock mechanism, avoiding weight increase on the clock side, and avoiding exposure of magnetic metal. It is air-core type. Therefore, when applied to an electronic device in which such a problem does not occur, a coil having a magnetic core may be employed. However,
If the signal frequency applied to the coil is sufficiently high, the air-core type is sufficient.

[1.2] Schematic Configuration of Electronic Timepiece Next, the schematic configuration of the electronic timepiece will be described. FIG. 3 is a schematic block diagram of a main part of the electronic timepiece. Electronic clock 2
00 is roughly divided into a clock coil 210 that functions as an antenna for transmitting and receiving electromagnetic coupling data, a secondary battery 220 that functions as a power storage unit, a current consumption detection circuit 230 that detects current consumption of a load 232 described below, Secondary battery 22
A limiter circuit 231 for electrically disconnecting the secondary battery 220 from the clock-side coil 210 when the voltage of 0 becomes equal to or higher than a predetermined limit voltage;
And a load 232 such as a transmission / reception circuit for receiving or transmitting the signal via the clock 0 and a clock circuit for displaying the time,
A control circuit 236 for controlling the entire system, an input unit 237 for the user to input various data, and a control circuit 236.
A display unit 238 for displaying various information under the control of the battery, and a backflow prevention element functioning as a backflow prevention element for rectifying the charging current from the clock side coil 210 and preventing discharge from the secondary battery 220 to the clock side coil 210 Diode 23
9 is provided. Limiter circuit 231
Is the limit control signal SL when the voltage of the secondary battery 220 exceeds a reference voltage Vreg corresponding to a predetermined allowable voltage.
When the comparator 241 that sets M to the “H” level and the limit control signal SLIM output from the comparator 241 is at the “H” level, the comparator 241 is turned on, and the clock side coil 2
A first transistor switch 242 for electrically disconnecting the secondary battery 220 from the clock-side coil 210 by forming a closed loop between the ten output terminals, and which is normally turned off and controlled under the control of the control circuit 236 A second transistor switch 2 for forcibly bringing the limiter circuit 231 into an operating state when the current consumption of the load 232 is rapidly reduced.
43.

[1.3] Principle of First Embodiment Here, the relationship between the charging voltage of the secondary battery 220 and the charging current will be described. FIG. 4 shows an equivalent circuit diagram of the secondary battery 220. As shown in FIG. 4, when the true battery voltage of the secondary battery 220 is V0 and the internal resistance of the secondary battery 220 is r, when the charging current Ij flows, the charging voltage VD of the secondary battery 220 Is represented by the following equation. VD = V0 + Ij · r Therefore, the load 23 exceeds the response characteristic of the comparator 241.
2, the charging current Ij increases rapidly, and the charging voltage VD of the secondary battery 220 decreases to the allowable voltage Vreg.
May be exceeded. Therefore, in the first embodiment, when the current consumption IL of the load 232 is rapidly reduced beyond the response characteristic of the comparator 241, the second
The transistor switch 243 is turned on by the control signal S1 from the control circuit 236, the gate voltage VG of the first transistor switch 242 is forcibly set to the “H” level, and the first transistor switch 242 is turned on.
The bypass current IS is rapidly increased. As a result, the charging current Ij does not increase, so that the charging voltage VD of the secondary battery 220 can be prevented from exceeding the allowable voltage Vreg.

[1.5] Operation of First Embodiment Next, the operation of the electronic timepiece 200 of the first embodiment will be described mainly on the operation during charging. In the initial state, the limiter circuit 231 is in a non-operating state, and the second transistor switch 243 is also off. As shown in FIGS. 1 and 2, the electronic timepiece 200 is installed at a predetermined position of the station 100, and a current is applied to the station-side coil 110 in a state where the station-side coil 110 is brought close to the clock-side coil 210 of the electronic timepiece 200. When flowing, the clock side coil 210 and the station side coil 110
The charging current IIN flows by electromagnetic coupling or electromagnetic induction. In parallel with this, the current consumption detection circuit 230
The change of the consumed current IL of 32 is monitored using a differentiating circuit or the like, and if the consumed current IL sharply decreases, the control circuit 236 is notified of that.

[1.5.1] When the decrease in the current consumption IL is gradual When the decrease in the current consumption IL is gradual enough to follow the response characteristics of the comparator 241, the limiter circuit 23
The comparator 241 is connected to the voltage VD of the secondary battery 220.
Is detected whether or not exceeds a reference voltage Vreg corresponding to a predetermined allowable voltage. If the voltage VD of the secondary battery 220 exceeds the reference voltage Vreg corresponding to the predetermined allowable voltage, a limit control signal is detected. SLIM is set to “H” level. As a result, the first transistor switch 242 is turned on, and a closed loop is formed between the output terminals of the clock-side coil 210 so that the secondary battery 220
Electrically disconnect from 0. As a result, the bypass current IS
Flows, and the battery voltage VD is controlled so as not to exceed the allowable voltage Vreg.

[1.5.1] When the consumption current IL decreases sharply Next, a case where the consumption current IL decreases sharply will be described with reference to the timing chart of FIG. In this case, the input current I input through the clock side coil 210
IN is 15 [mA] and is in the initial state (at time t in FIG. 5).
The current consumption IL of the load 232 in 1) is 10 [mA].
It is assumed that As shown at time t2, the consumption current IL
If the decrease (10 [mA] → 0.1 [mA]) suddenly exceeds the response characteristic of the comparator 241, the load 232
Of the current consumption IL of the first transistor switch 242 of the limiter circuit 231 can be observed.
It remains off. At this time, the current consumption detection circuit 2
The control circuit 30 indicates that the consumption current IL has sharply decreased.
36 will be notified.

As a result, at time t2, the control circuit 2
36 outputs the control signal S1 at the "L" level as shown in FIG. As a result, the second transistor switch 243 is turned on, and the gate voltage VG of the first transistor switch 242 is turned on as shown in FIG.
Is forced to the "H" level to turn on the first transistor switch 242, and the bypass current IS is rapidly increased (0 [mA] → 15 [mA]; see FIG. 5 (f)). As a result, as shown in FIG. 5G, the substantial charging current Ij does not increase, so that the charging voltage VD of the secondary battery 220 can be prevented from exceeding the allowable voltage Vreg. After that, the comparator 2 of the limiter circuit 231
After a lapse of time that the secondary battery 41 can follow, the voltage VD of the secondary battery 220 becomes equal to the reference voltage Vreg corresponding to a predetermined allowable voltage.
Is detected, and when the voltage VD of the secondary battery 220 exceeds the reference voltage Vreg corresponding to a predetermined allowable voltage, the limit control signal SLIM is set to the “H” level. As a result, the gate voltage VG of the first transistor switch 242 can be maintained in the on state without being forced to the “H” level, so that at time t3, the control circuit 236 changes the control signal S1 to “ The H level is set, and the second transistor switch 243 is turned off. Therefore, the charging voltage VD of the secondary battery 220 does not exceed the allowable voltage Vreg.

[1.6] Effects of First Embodiment As described above, according to the first embodiment, the voltage of the secondary battery does not exceed the allowable voltage during charging. It is possible to suppress the deterioration of the secondary battery due to the above.

[2] Second Embodiment [2.1] Configuration of Second Embodiment FIG. 6 shows a circuit configuration around a limiter circuit of an electronic timepiece according to a second embodiment. 6, the same parts as those in the first embodiment in FIG. 3 are denoted by the same reference numerals. The limiter circuit 231A of the second embodiment is different from the limiter circuit 231 of the first embodiment.
The difference is that a delay circuit 250 for delaying the voltage drop rate of the gate voltage VG of the first transistor switch 242 is provided. The delay circuit 250 includes an output terminal of the comparator 241 and the first transistor switch 24.
And a capacitor C1 connected between a connection point between the gate terminal of the first transistor switch 242 and the resistor R1 and the ground-side power supply.
It is comprised including. The reason for providing this delay circuit 250 is that the gate voltage V
This is to prevent G from decreasing and the charging current Ij from undesirably increasing. More specifically, as shown in FIG. 7A, time t3 (the same timing as time t3 in FIG. 5)
7, when the control signal S1 changes from "L" level to "H" level, the gate voltage VG of the first transistor switch 242 is gradually decreased as shown in FIG. Is shifted to an operable state, and the charging current Ij is prevented from increasing rapidly as shown in FIG. 7 (e).

[2.2] Effects of the Second Embodiment As described above, according to the second embodiment, the gate voltage VG decreases before the comparator 241 responds, and the charging current Ij is reluctant. To prevent
During charging, it is possible to reliably prevent the voltage of the secondary battery from exceeding the allowable voltage.

[2.3] Modification of Second Embodiment FIG. 8 shows a modification of the second embodiment. 8, the same parts as those in the second embodiment in FIG. 6 are denoted by the same reference numerals.
The difference between the limiter circuit 231B of the modification of the second embodiment and the limiter circuit 231A of the second embodiment is that the delay of the output signal of the comparator 241 when the control signal S1 is at the “H” level can be prevented. And a delay circuit 250A capable of delaying the voltage drop rate of the gate voltage VG of the first transistor switch 242. The delay circuit 250A includes a comparator 241
251 having an input terminal connected to the output terminal of the inverter 251
A third transistor switch 252 having a gate terminal connected to the output terminal of the inverter 251, a resistor R1 connected between the source terminal of the third transistor switch 252 and the ground side power supply, and a third transistor switch 25.
2 and a capacitor C2 connected between the ground-side power supply. Delay circuit 250A
Is the same as that of the second embodiment when the control signal S1 changes from “L” level to “H” level. However, when the control signal S1 is at the “H” level,
The output signal of the comparator 241 is transmitted to the third transistor switch 252 via the inverter 251.
The amount of delay is reduced and the first transistor switch 24 is not affected by the resistance R2 and the capacitor C2.
2 can be operated.

[3] Third Embodiment [3.1] Configuration of Third Embodiment FIG. 9 shows a circuit configuration around a limiter circuit of an electronic timepiece according to a third embodiment. In FIG. 9, the same parts as those in the first embodiment in FIG. 3 are denoted by the same reference numerals. The limiter circuit 231C of the third embodiment is different from the limiter circuit 231 of the first embodiment.
A different point from the first embodiment is that a voltage detection circuit 260 for detecting a charging voltage of the secondary battery 220 is provided, and the battery voltage VD of the secondary battery is set to a plurality of predetermined value voltages (three types in FIG. 9) in advance. The difference is that control signals S1 to S3 are output based on the relationship between the value voltage and the battery voltage VD to control the operation of the limiter circuit 231C or the amount of bypass current. The limiter circuit 231C has the same configuration as the limiter circuit 231, and is turned on by a voltage detection circuit 260 that detects a voltage at the time of charging the secondary battery 220 and a control signal S3 from the control circuit 236. Is connected to the first transistor switch 242 in series, and the fourth transistor 2 is connected to the first transistor switch 242 by turning on the resistor R3 in response to a control signal S2 from the control circuit 236.
62 are provided.

[3.2] Operation of Third Embodiment The main operation of the limiter circuit 231C will now be described with reference to FIG. As shown at time t1, when the load current IL decreases sharply (11 [mA] → 0.1
[MA], the control circuit 236 determines that the load current IL has rapidly decreased based on the voltage detection result of the voltage detection circuit 260, and sets the control signal S1 and the control signal S3 to the “L” level. . As a result, the second switch transistor 243 and the fourth switch transistor 262 are turned on, the first switch transistor 242 is immediately turned on, and the bypass current IS flows. At this time, the bypass current IS flows through the fourth switch transistor 262 without passing through the resistors R2 and R3, and the large bypass current IS (= 15)
[MA]). Also, as shown at time t2, when the load current IL sharply decreases (7
[MA] → 0.1 [mA]), the control circuit 236 determines that the load current IL has rapidly decreased based on the voltage detection result of the voltage detection circuit 260, and the control signal 236 controls the control signal S1 and the control signal S2. At the “L” level.

As a result, the second switch transistor 24
The third and third switch transistors 261 are turned on, the first switch transistor 242 is immediately turned on, and the bypass current IS flows.
At this time, the third switch transistor 261 allows the bypass current IS to flow only through the resistor R3, and allows the middle bypass current IS (= 11 [mA]) to flow. Further, as shown at time t3, when the load current IL decreases a little sharply (1 [mA] → 0.
1 [mA]), it is determined that the load current IL has sharply decreased based on the voltage detection result of the voltage detection circuit 260,
The control circuit 236 sets only the control signal S1 to the “L” level. As a result, the second switch transistor 243 becomes
The first switching transistor 242 is turned on,
It is immediately turned on, and the bypass current IS flows. At this time, the bypass current IS flows through the resistors R2 and R3, and a small bypass current IS (= 7 [mA]) can flow.

[3.3] Effect of Third Embodiment As described above, according to the third embodiment, since the bypass current can be controlled according to the voltage of the secondary battery, the secondary The charging efficiency can be improved while preventing the battery from deteriorating.

[3.4] Modification of Third Embodiment [3.4.1] First Modification In the third embodiment described above, the resistor R is connected to the bypass path.
Although the configuration in which the bypass current IS is controlled by inserting one of R2 and R3 has been adopted, the first modification controls the bypass current IS by controlling the gate voltage of the first transistor switch. This is an example of the case. Limiter circuit 231 according to a first modification of the third embodiment
D is a resistor R connected in series as shown in FIG.
4, a voltage dividing circuit 271 having R5 and R6, and a control circuit 2
The power supply voltage is turned on by the control signal S4 from the control signal V.36, and the power supply voltage is effectively divided by the resistors R5 and R6.
A transistor switch 272 that generates C and a transistor switch 273 that is turned on by a control signal S5 from the control circuit 236 to output the power supply voltage as it is and generate the control voltage VC are provided.
Accordingly, the gate voltage VG of the first transistor switch 242 is controlled by the control voltage VC obtained by dividing the power supply voltage by the combined resistance of the resistors R4 and R5 and the resistor R6. It can correspond to either the control voltage VC obtained by dividing the voltage at R6 or the control voltage VC obtained by directly outputting the power supply voltage, and the same effect as in the third embodiment can be obtained. Can be. [3.4.2] Second Modification In the above description, the case where the bypass current IS is controlled in three stages has been described, but it is also possible to control the bypass current IS in four or more stages based on the same concept.

[4] Modification of Embodiment [4.1] First Modification In the above embodiment, the state of charge is determined based on the voltage of the secondary battery 220. It is also possible to configure to make a determination based on the change in the charging current.

[4.2] Second Modification In the above embodiment, the size of the load is detected by using the current consumption detection circuit. However, the configuration is such that the heavy load detection circuit for detecting the heavy load is used. It is also possible.

[4.3] Third Modification In the above embodiment, the station 10 is used as an electronic device.
0, the electronic timepiece 200 has been described as an example of the electronic device to be charged. However, the present invention is not limited to this. For example, an electric toothbrush,
Electric shaving, cordless phone, mobile phone, personal handy phone, mobile PC, PDA (Personal
The present invention is applicable to a device to be charged including a secondary battery such as a digital assistant (personal information terminal) and the charging device.

[0038]

According to the present invention, even when the voltage of the secondary battery is in the vicinity of the allowable voltage, the charging current is rapidly changed based on the current consumption of the load and the size of the load. Even if there is a change, the charging current accompanying the charging is controlled in accordance with the change and the voltage of the secondary battery is controlled so as not to exceed the allowable voltage, so that the deterioration of the secondary battery is suppressed and the length of the secondary battery is reduced. It is possible to extend the service life of the electronic device equipped with the secondary battery.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a station and an electronic timepiece according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of the station and the electronic timepiece according to the embodiment of the present invention.

FIG. 3 is a schematic configuration block diagram of a main part of the electronic timepiece according to the first embodiment.

FIG. 4 is a diagram for explaining a charging voltage of a secondary battery.

FIG. 5 is a timing chart for explaining the operation of the first embodiment.

FIG. 6 is a schematic configuration block diagram of a main part of an electronic timepiece according to a second embodiment.

FIG. 7 is a timing chart for explaining the operation of the second embodiment.

FIG. 8 is a schematic block diagram of a main part of an electronic timepiece according to a modification of the second embodiment.

FIG. 9 is a schematic block diagram of a main part of an electronic timepiece according to a third embodiment.

FIG. 10 is a timing chart for explaining the operation of the third embodiment.

FIG. 11 is a schematic block diagram of a main part of an electronic timepiece according to a modification of the third embodiment.

FIG. 12 is a schematic configuration block diagram of a main part of a conventional electronic timepiece.

FIG. 13 is a diagram for explaining a conventional problem.

[Explanation of symbols]

 100: Station 104: Display unit 110: Station side coil 200: Electronic clock 210: Clock side coil 220: Secondary battery 230: Current consumption detection circuit 231: Limiter Circuit 232 Load 236 Control circuit 237 Input unit 238 Display unit 239 Backflow prevention diode 241 Comparator 242 First transistor switch 243 Second Transistor switch

 ──────────────────────────────────────────────────の Continued on the front page (72) Koji Kitazawa 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation F-term (reference) 5G003 AA01 BA01 CC04 DA04 GA01 GB08 GC06 5H030 AA03 AA06 AA10 AS11 BB01 FF42 FF43

Claims (11)

[Claims] A power storage device that can be charged from the outside and that is set so that a charging voltage does not exceed a predetermined allowable voltage, and a load device that is driven by electric power stored in the power storage device. In the electronic device having: a charging current bypass unit that bypasses a charging current by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage; and a consumption current detection unit that detects a consumption current in the load device. An electronic device, comprising: a forced bypass unit for forcibly bypassing the charging current via the charging current bypass unit based on the magnitude of the consumed current. 2. A power storage device which can be charged from the outside and whose charging voltage is set so as not to exceed a predetermined allowable voltage, and a load device driven by the electric power stored in the power storage device. An electronic device having: a charging current bypass unit configured to bypass a charging current by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage; and a heavy load detecting a magnitude of a load in the load device. An electronic device comprising: a detection unit; and a forced bypass unit that forcibly bypasses the charging current via the charging current bypass unit based on the magnitude of the load. 3. The electronic device according to claim 1, wherein the forcible bypass unit includes a resistance value control unit for forcibly reducing a flow path resistance value of the charging current in the charging current bypass unit. Electronic equipment characterized by the above. 4. The electronic device according to claim 1, wherein the charging current bypass unit includes a resistance element, a backflow prevention element, and the resistance element connected in parallel to the power storage device via the backflow prevention element. And a second switch for controlling the first switch to forcibly connect the resistance element to the power storage device in parallel. An electronic device comprising: a second switch control unit that controls two switch units. 5. The electronic device according to claim 4, wherein the first switch means is a comparator, and wherein the resistance element is a transistor having the output of the comparator input to a control terminal as a control signal. The electronic device, wherein the switch means is a transistor that outputs a control signal to the control terminal for forcibly turning the transistor on. 6. The electronic device according to claim 1, wherein the charging current bypass unit includes a variable resistance unit that can change a resistance value, and a charging current or the allowable voltage that determines a resistance value of the variable resistance unit. An electronic device comprising: a resistance value control unit that performs control based on: 7. The electronic device according to claim 1, wherein after the charging current is forcibly bypassed through the charging current bypass unit, a return speed at the time of returning is reduced. An electronic device comprising means. 8. A power storage device which can be charged from the outside and whose charging voltage is set so as not to exceed a predetermined allowable voltage, and a load device driven by electric power stored in the power storage device. A control method of an electronic device having a charging current bypass step of bypassing a charging current by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage; and a consumption detecting a consumption current in the load device. A method for controlling an electronic device, comprising: a current detection step; and a forced bypass step of forcibly bypassing the charging current based on the magnitude of the consumed current. 9. A power storage device that can be charged from the outside and is set so that a charging voltage does not exceed a predetermined allowable voltage, and a load device that is driven by power stored in the power storage device. A control method of an electronic device having a charging current bypass step of bypassing a charging current by a predetermined amount so that a charging voltage in the charging device does not exceed the allowable voltage; and detecting a magnitude of a load in the load device. A heavy load detection step, and a forced bypass step of forcibly bypassing the charging current based on the magnitude of the load. 10. The control method for an electronic device according to claim 8, wherein the forcible bypass step forcibly reduces a resistance value of a flow path of the charging current for bypassing the charging current. A method for controlling an electronic device, comprising a resistance value control step. 11. The control method for an electronic device according to claim 8, wherein a flow path of the charging current for bypassing the charging current includes a resistance element, a backflow prevention element, and the resistance element. And a first switch that is connected to the power storage device in parallel via the backflow prevention element. The forced bypass step controls the first switch to forcibly connect the resistance element to the power storage device. And controlling a forced switch to be connected in parallel via the backflow prevention element.