JP5805462B2 - Electronic clock - Google Patents

Description

  The present invention relates to an electronic timepiece including a power generation unit and a power storage unit.

2. Description of the Related Art Conventionally, an electronic timepiece having a power generation means and a power storage means and capable of operating permanently without battery shortage has been commercialized.
Here, a solar battery is generally used as the power generation means, and a coin-type lithium secondary battery is generally used as the power storage means. A lithium secondary battery is a battery using lithium as an electrode, and is a storage battery that has been rapidly spreading in recent years. Unlike a lithium primary battery that can only discharge DC power that has been known for a long time, it is a storage battery that stores electricity by charging.

  On the other hand, an electronic timepiece having a radio wave correction function that receives a standard radio wave including time information and automatically corrects the time has also been developed, and has the radio wave correction function and the power generation unit and the power storage unit described above. So-called solar radio correction watches have been commercialized.

Such a solar radio correction watch receives a standard radio wave manually or automatically at a predetermined time, but this receiving operation requires a relatively large amount of power, and a lithium secondary battery as a power storage means as a power source It becomes a big load.
There are several types of lithium secondary batteries, such as those with a storage voltage of 2.5V and types with 1.5V, and the performance is different, but each battery has a relatively high internal impedance. There is a risk that the watch system malfunctions when the stored voltage drops when receiving radio waves. For this reason, a secondary battery with low internal impedance is required as a power storage means of a solar radio correction watch.

  From such a demand, it is conceivable to use a lithium ion secondary battery (hereinafter abbreviated as Li ion secondary battery) having a high capacity and a low internal impedance as power storage means of a solar radio correction watch. The lithium ion secondary battery is the same as the lithium secondary battery in that lithium is used as an electrode, but is a storage battery in which lithium ions in the electrolyte bear electric conduction.

  That is, if a Li-ion secondary battery is used for a solar radio wave correction watch, the problem of load on the battery when receiving a standard radio wave can be reduced, and malfunction of the watch system due to a decrease in stored voltage can be prevented. In addition, since the Li-ion secondary battery has a high capacity, even if the watch cannot be charged for a long time without being exposed to light, the watch will stop if it is fully charged. Can be avoided.

However, Li ion secondary batteries are generally limited in the allowable charging temperature range (for example, 0 ° C. to + 45 ° C.) from the viewpoint of safety. If charging is continued in an environment outside the allowable charging temperature range, abnormal heat generation, ignition, or, in the worst case, explosion may occur depending on battery characteristics.
Therefore, when using a Li-ion secondary battery as the power storage means of an electronic timepiece, the electronic timepiece is equipped with a temperature detection means, measures the ambient temperature, acquires temperature information, and controls charging based on the temperature information. It is essential to do.

From the background as described above, the temperature detection and charge control techniques used in the conventional electronic timepiece will be examined with reference to three patent documents.
First, an electronic timepiece that includes an oscillation circuit having a primary temperature characteristic as temperature detection means and compensates for the temperature characteristic of a crystal oscillation circuit having a secondary temperature characteristic by using a change in the oscillation frequency as temperature information is known (for example, (See Patent Document 1).

  According to this electronic timepiece, the secondary temperature characteristic of the crystal oscillation circuit can be compensated by the temperature information from the temperature detecting means, and a stable rate can be obtained with respect to temperature change, thereby providing a highly accurate electronic timepiece. It has been shown that it can.

  Also known is an electronic timepiece having a rate adjusting means for correcting temperature characteristics of a crystal oscillation circuit, a temperature measuring means for determining an adjustment amount of the rate adjusting means, and a power storage means (for example, Patent Document 2). reference.).

  The electronic timepiece adjusts the rate based on the temperature information from the temperature measuring unit, and stops the temperature measuring unit when the voltage of the power storage unit falls below a predetermined voltage value, and sets the adjustment amount of the rate adjusting unit to a predetermined level. The rate adjusting means is continuously operated as the adjustment amount. Thus, it is shown that when the voltage of the power storage means is lowered, erroneous correction of the rate adjusting means due to malfunction of the temperature measuring means can be avoided.

  There is also known an electronic timepiece having a power storage means, a charging means, a clock control circuit that operates using electric power from the power storage means, a display means, and a voltage detection circuit that detects the voltage of the power storage means ( For example, see Patent Document 3.)

  This electronic timepiece stops the operation as a timepiece by stopping the oscillation circuit, the frequency divider circuit, the functional circuit, etc. of the timing control circuit after a predetermined time elapses when the voltage of the power storage means becomes lower than the predetermined voltage. When the voltage of the power storage means becomes equal to or higher than a predetermined voltage, the stop of the clock operation is released. Thus, it is shown that overdischarge of the power storage means can be prevented and restartability when the voltage of the power storage means is recovered can be improved.

Japanese Utility Model Publication No. 1-66097 (page 5-9, FIG. 1) Japanese Patent No. 3753839 (page 3, FIG. 1) Japanese Patent No. 3702729 (page 11, FIG. 2)

  However, the electronic timepiece of Patent Document 1 includes an oscillation circuit having a primary temperature characteristic built in a timepiece IC (Integrated Circuit) as temperature detection means, and this temperature detection means is used for charging a Li-ion secondary battery. Although it is technically possible to apply to the control, a charge control circuit including a temperature detection means is provided to perform temperature control by acquiring temperature information on the assumption that a Li-ion secondary battery is used. If the watch IC (in this case, including the case where the IC is a microcomputer) is incorporated, the watch IC stops when the storage voltage of the Li-ion secondary battery decreases, and the temperature detection means built in the watch IC is provided. Since the charging control circuit including it is also stopped, there is a problem that charging cannot be continued when the storage voltage of the Li ion secondary battery is lowered.

  In the electronic timepiece of Patent Document 2, the rate adjusting unit determines the rate adjustment amount based on the temperature information from the temperature measuring unit, but the temperature information is not used for charging control of the power storage unit. For this reason, when using a Li ion secondary battery in which the charging permission temperature range is limited as the power storage means, there is a risk that the charging operation is performed in a state where the charging permission temperature range is removed. The secondary battery cannot be used.

  Further, the electronic timepiece of Patent Document 3 stops the timepiece system and prevents overdischarge of the power storage means due to the voltage drop of the power storage means, but does not use temperature information for charge control of the power storage means. For this reason, when using a Li ion secondary battery in which the charging permission temperature range is limited as the power storage means, there is a risk that the charging operation is performed in a state exceeding the charging permission temperature range. The secondary battery cannot be used.

[Description of problems with conventional solar clock system: Fig. 12]
In order to sort out and clarify the problems of the electronic timepiece having the conventional power generation means and the power storage means as described above, a solar timepiece system that is a combination of technologies known in Patent Documents 1 to 3 is developed. As an example, a problem when a Li ion secondary battery is used as a power storage means will be examined in detail with reference to FIG.
Here, as described above, the solar timepiece system is an electronic timepiece system in which a solar battery is mounted as a power generation means, and a secondary battery as a power storage means is charged with an electromotive force from the solar battery to obtain power of the timepiece. Say.

  FIG. 12 is a block diagram of a conventional solar timepiece system, in which a Li-ion secondary battery is used as a power storage means. In FIG. 12, reference numeral 200 denotes an electronic timepiece as a conventional solar timepiece system. The electronic timepiece 200 displays a system control unit 210 including a plurality of electronic components, a secondary battery 230 as a power storage unit, a solar cell 240 as a power generation unit (indicated as “SC” in the drawing), and a time. The display unit 250 and the like are configured. The system control unit 210 includes a crystal oscillator 211, a clock IC 220, an operation stop switch S1, a charge control switch S2, a diode D1 for preventing backflow (hereinafter abbreviated as a diode D1), and the like.

  The timepiece IC 220 is composed of a timepiece microcomputer that operates with low power consumption, a crystal oscillation circuit 221 that generates a reference clock P1 by a crystal resonator 211, a timepiece circuit 222 that inputs a reference clock P1 and measures time, and a secondary battery When the storage voltage VBT 230 is monitored and becomes equal to or lower than a predetermined voltage, temperature information is obtained by a frequency difference between the operation stop control circuit 223 that outputs the stop signal P2 and the CR oscillator 224 that receives the reference clock P1 and is incorporated. The temperature detection circuit 225 includes a charge control circuit 226 that inputs temperature data P3 from the temperature detection circuit 225, performs charge control, and outputs a charge control signal P4.

  The positive terminal of the solar battery 240 is connected to the circuit GND, the negative terminal of the solar battery 240 is connected to one terminal of the charge control switch S2 as the generated voltage VHD, and the other terminal of the charge control switch S2 is the diode D1. The anode of the diode D1 is connected to one terminal of the operation stop switch S1, and the other terminal of the operation stop switch S1 is supplied to the timepiece IC 220 as the storage voltage VBT ′.

The secondary battery 230 is a Li-ion secondary battery, the positive terminal is connected to the circuit GND, and the negative terminal is connected to the connection point between the anode of the diode D1 and one terminal of the operation stop switch S1 as the storage voltage VBT. Is done. The stored voltage VBT is also connected to the operation stop control circuit 223 of the timepiece IC 220.
Here, if the GND of the circuit is used as a reference, the generated voltage VHD and the storage voltage VBT are negative potential voltages.

  The display unit 250 inputs time data P5 from the clock circuit 222 of the clock IC 220 and displays the time. Here, if the electronic timepiece 200 is a digital timepiece, the display unit 250 digitally displays the time using a liquid crystal panel or the like. If the electronic timepiece 200 is an analog timepiece, the display unit 250 includes a step motor, dial, hour hand, The time is displayed with a minute hand.

Next, an outline of the operation of the conventional electronic timepiece 200 will be described.
In FIG. 12, when light is applied to the solar cell 240, an electromotive force is generated, and a generated voltage VHD having a predetermined voltage value is generated. Since the charging control circuit 226 of the watch IC 220 turns on the charging control switch S2 in a normal state by the charging control signal P4, the secondary battery 230, the diode D1, the charging control switch S2, the solar battery 240 through the GND from the positive terminal of the solar battery 240. A current path is formed to the negative terminal of the battery 240, the charging current Icg from the solar battery 240 flows to the secondary battery 230, and the secondary battery 230 is charged.

  Since the operation stop control circuit 223 of the timepiece IC 220 turns on the operation stop switch S1 in a normal state, the power storage voltage VBT ′ from the secondary battery 230 is supplied to the timepiece IC 220 via the operation stop switch S1, and crystal oscillation occurs. The circuit 221 oscillates, the clock circuit 222 performs a time measuring operation and outputs time data P5, and the display unit 250 displays the time. Accordingly, if the solar battery 240 is continuously irradiated with light, the secondary battery 230 is continuously charged and the watch IC 220 continues to operate, so that the display unit 250 can continuously display the time. .

Next, when the solar battery 240 is no longer irradiated with light, the power generation voltage VHD decreases, so the charging of the secondary battery 230 is stopped, but the storage voltage VBT is supplied by the electric power stored in the secondary battery 230, The clock IC 220 continues to operate. Here, if the secondary battery 230 is not charged for a long period of time, the power stored in the secondary battery 230 decreases, and when the storage voltage VBT decreases and becomes lower than the minimum operating voltage of the timepiece IC220, the timepiece IC220. Operation becomes unstable.
In order to avoid this state, the operation stop control circuit 223 monitors the storage voltage VBT, outputs a stop signal P2 at a predetermined voltage value before the operation of the timepiece IC 220 becomes unstable, and the operation stop switch S1. Is turned off. As a result, the stored voltage VBT ′ becomes zero volts, and the power supply to the timepiece IC 220 is stopped. Therefore, the electronic timepiece 200 can stably stop its operation without causing an unstable malfunction.

On the other hand, the temperature detection circuit 225 obtains temperature information based on the difference between the frequency of the reference clock P1 and the frequency of the built-in CR oscillator 224, and outputs temperature data P3.
The charge control circuit 226 receives the temperature data P3, determines whether the ambient temperature is within the allowable charging temperature range of the secondary battery, and outputs the charging control signal P4 when the temperature is out of the allowable temperature range. To turn off the charging control switch S2.
When the charging control switch S2 is turned off, the current path of the charging current Icg flowing to the secondary battery 230 is interrupted, so that charging of the secondary battery 220 is forcibly stopped. By this operation, when the secondary battery 230 is a Li-ion secondary battery, it is possible to prevent charging at a temperature outside the charge permission temperature range.

  However, if the irradiation of light to the solar battery 240 is interrupted and the secondary battery 230 is not charged for a long period of time, the storage voltage VBT decreases as described above, the operation stop switch S1 is turned off, and the timepiece IC 220 is turned off. Stops working. Since the temperature detection circuit 225 and the charge control circuit 226 are built in the watch IC 220, both the temperature detection operation and the charge control operation are stopped, and the charge control switch S2 is also turned off.

  If the solar cell 240 is again irradiated with light in the function stop state of the timepiece IC 220, the secondary battery 230 can be charged. However, the temperature detection circuit 225 and the charge control circuit 226 are provided inside the timepiece IC 220. Since the function is stopped, the charge control switch S2 continues to be in the OFF state. As a result, the secondary battery 230 is not charged, and the electronic timepiece 200 cannot exit from the stopped state.

  Further, even if the operation stop control circuit 223 and the operation stop switch S1 are not present, and the function for stopping the operation of the timepiece IC 220 due to the voltage drop of the secondary battery 230 does not exist, the CR oscillator 224 of the temperature detection circuit 225 Since the oscillation frequency fluctuates greatly due to the voltage drop of the storage voltage VBT, correct temperature information cannot be acquired. As a result, the charging control circuit 226 cannot operate normally with respect to the temperature, and continues the charging operation even if it is out of the allowable charging temperature range, or conversely stops the charging even within the allowable charging temperature range. There is a risk of malfunction.

  As described above, in the timepiece system in which the temperature detecting means and the charging control means are incorporated in the conventional timepiece IC, when the timepiece IC is stopped due to the voltage drop of the storage voltage VBT, the charging control is also stopped, so that charging cannot be resumed. There are major challenges. Even in a system in which the clock IC does not stop, there is a risk that the charging control will malfunction.

  In other words, even if it is desired to use a Li-ion secondary battery having a high capacity and a low internal impedance as a power storage means of a solar radio correction watch, the conventional watch system as described above has a limitation in the allowable charging temperature range. There was a big problem that an ion secondary battery could not be used.

  The present invention solves the above-mentioned problem, and even if the clock voltage of the Li-ion secondary battery decreases and the timepiece IC stops operating, temperature detection and charge control are continued, and the charge permission temperature of the Li-ion secondary battery An object of the present invention is to provide an electronic timepiece capable of safely performing charging control within a range.

  In order to solve the above problems, the electronic timepiece of the present invention employs the following configuration.

  An electronic timepiece according to the present invention is an electronic timepiece including a power generation means, a power storage means having a limited charging permission temperature range, and a system control unit for controlling the operation of the timepiece. The system control unit is stored in the power storage means. Provided with a charge control unit that stops the operation when the power is below a predetermined value, operates with the power generated by the power generation means, detects the temperature, and controls to charge the power storage means within the charge permission temperature range It is characterized by.

  As a result, even if the power stored in the power storage means decreases and the system control unit stops operating, the charge control unit operates with the power generated by the power generation means. It is possible to continue and safely charge the power storage means.

  The charge control unit includes a temperature detection unit having two oscillation circuits having different temperature characteristics, and the temperature detection unit detects the temperature by comparing clock pulses generated by both oscillation circuits. May be.

  As a result, temperature information is acquired from the frequency difference between the two oscillation circuits, so that it is possible to realize highly accurate temperature detection that is less susceptible to the effects of IC manufacturing variations and power supply voltage fluctuations.

  In addition, two oscillation circuits provided in the charge control unit are constantly operated and the other is intermittently operated. The oscillation circuit that is always operating has a lower oscillation frequency than the oscillation circuit that is intermittently operated. Alternatively, the number of pulses of the clock pulse of the oscillation circuit that is intermittently operated may be counted based on the detection pulse generated based on the clock pulse of the oscillation circuit that is always operating, and the temperature may be detected based on the result. .

As a result, the frequency of one oscillation circuit that is always operating is low, and the other oscillation circuit is intermittently operated by a detection pulse generated based on the clock pulse of the oscillation circuit that is always operating. Electric power can be kept low, and the charge control unit can be operated with a slight electromotive force from the power generation means.

  Further, the two oscillation circuits provided in the charge control unit may have opposite temperature coefficients.

  Thereby, since the temperature coefficients of the two oscillation circuits are opposite to each other, the change in the frequency difference with respect to the temperature change can be increased, and the temperature detection with high sensitivity is possible.

  The charge control unit may include a booster circuit that boosts the power generated by the power generation means.

  Thereby, even if the voltage value of the electromotive force from the power generation means is low, it is possible to boost the voltage and charge the power storage means.

  Further, the clock pulse of the oscillation circuit that is always operating may be used as the system clock pulse of the charge control unit.

  Thereby, since it is not necessary to newly generate a clock for the charge control unit, the circuit scale of the charge control unit can be reduced and an increase in power consumption can be prevented. Further, when a booster circuit is provided, the booster clock can also be used.

  The charge control unit includes a voltage detection circuit that detects a storage voltage of the storage unit, and the voltage detection circuit controls to stop charging the storage unit when the storage voltage is equal to or lower than a predetermined voltage. It may be.

  Thereby, since the overdischarge of the power storage means can be detected and the charging operation can be stopped, the danger of charging the power storage means in the overdischarged state can be eliminated.

  The charging control unit includes a voltage detection circuit that detects a power generation voltage of the power generation means, and the voltage detection circuit controls to stop charging the power storage means when the power generation voltage is equal to or lower than a predetermined voltage. It may be.

  As a result, the charging operation can be stopped by detecting a decrease in the power generation voltage of the power generation means, so that the risk of malfunctioning charging control when the temperature detection error of the temperature detection unit increases due to a low voltage can be eliminated. it can.

  The voltage detection circuit may perform a sampling operation based on a clock pulse of an oscillation circuit that is always operating.

  As a result, it is not necessary to generate a new clock for the sampling operation of the voltage detection circuit, so that the circuit scale of the charge control unit can be reduced.

  According to the present invention, even when the operation of a system control unit (for example, a clock IC) that controls the operation of the timepiece due to the voltage drop of the charging unit is stopped, the charging of the Li ion secondary battery can be safely continued. , Can increase the reliability of the watch.

According to the present invention, a Li-ion secondary battery having a high capacity and a small internal resistance can be used for an electronic timepiece having a power generation means and a power storage means. As a result, the electronic timepiece can be used for a long time without being charged frequently, and the time information receiving operation in the solar radio wave correction timepiece requiring a relatively large current can be stably performed.

It is a block diagram explaining the basic concept of the electronic timepiece of the present invention. It is a block diagram explaining embodiment of the electronic timepiece of this invention. It is a circuit diagram which shows an example of the oscillation circuit incorporated in the temperature detection part of embodiment of this invention. It is a graph which shows the temperature characteristic of the oscillation circuit incorporated in the temperature detection part of embodiment of this invention. It is a block diagram which shows an example of a structure of the judgment part incorporated in the temperature detection part of embodiment of this invention. It is a timing chart explaining operation | movement at the time of giving large temperature dependence to oscillation circuit OSC1 of the temperature detection part of embodiment of this invention. It is a timing chart explaining operation | movement at the time of giving large temperature dependence to oscillation circuit OSC2 of the temperature detection part of embodiment of this invention. FIG. 2 is a circuit diagram illustrating an example of a voltage detection circuit according to an embodiment of the present invention, and a timing chart illustrating the operation thereof. It is a circuit diagram which shows an example of the charge control circuit and booster circuit of embodiment of this invention. It is a flowchart explaining the charge control operation example 1 of embodiment of this invention. It is a flowchart explaining the charge control operation example 2 of embodiment of this invention. It is a block diagram explaining the structure of the conventional electronic timepiece.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, in order to help understanding of the present invention, the basic concept of the present invention will be described with reference to FIG.
The feature of the basic concept of the present invention is that the system controller that controls the operation of the watch and the charge controller that controls the charging of the Li-ion secondary battery are separated, and the system controller is driven by the Li-ion secondary battery. The charge control unit is driven by a solar cell. With such a configuration, even if the system control unit stops due to a voltage drop of the Li ion secondary battery, the charge control unit continues to charge the Li ion secondary battery.

  For example, the system control unit that controls the operation of the timepiece and the charge control unit that controls charging are separated from each other by, for example, an independent IC chip configuration in which the system control unit is a clock IC and the charge control unit is a charge control IC Then, it becomes easy to make it operate | move with different power supply means, such as a Li ion secondary battery and a solar cell. In the following description, an example in which IC chips are divided in this way will be used.

[Description of Configuration of Basic Concept of the Present Invention: FIG. 1]
FIG. 1 is a block diagram showing the basic concept of the present invention.
In FIG. 1, reference numeral 1 denotes an electronic timepiece having the basic concept of the present invention. The electronic timepiece 1 is the solar timepiece system described above, and includes a system control unit 2 that controls the operation of the timepiece, a charge control unit 3 that performs charge control of the power storage means, a Li ion secondary battery 4 as the power storage means, It is comprised by the solar cell 5 (it describes with "SC" in a figure) etc. as a means.

A part of the configuration of the basic concept of the present invention shown in FIG. 1 is common to the conventional electronic timepiece 200 (see FIG. 12) already described. Such elements are given the same numbers, and redundant descriptions are omitted.
The electronic timepiece 1 also has a display unit for displaying the time, but it is not directly related to the present invention and is not shown.

  The system control unit 2 includes a timepiece IC 10, an external operation stop switch S1, and a diode D1. The operation stop switch S1 and the diode D1 may be built in the timepiece IC 10. In this case, the operation stop switch S1 can be a semiconductor switch using a field effect transistor or the like.

The timepiece IC 10 is composed of a timepiece microcomputer that operates with low power consumption, and includes a crystal oscillation circuit 11 that generates a reference clock P10, a timepiece circuit 12 that inputs the reference clock P10 and measures the time, and the storage of the Li ion secondary battery 4. When the voltage VBT is monitored and becomes equal to or lower than a predetermined voltage, the operation stop control circuit 13 outputs a stop signal P11.
The stop signal P11 is connected to the control terminal of the operation stop switch S1 to control ON (for example, roadway) and OFF (for example, open) of the operation stop switch S1. A crystal resonator is connected to the crystal oscillation circuit 11 but is not shown.

  The charge control unit 3 includes a charge control IC 20 and a charge control switch S2. The charge control switch S2 may be built in the charge control IC 20 as in the case of the system control unit 2 described above. In this case, the charge control switch S2 is a semiconductor switch using a field effect transistor or the like. It can be.

The charge control IC 20 detects a temperature and outputs a temperature detection signal P12. The charge control IC 20 outputs a charge control signal P13 that controls charging of the Li-ion secondary battery 4 based on the temperature detection signal P12. And circuit 70.
The charge control signal P13 is connected to the control terminal of the charge control switch S2 and controls ON / OFF of the charge control switch S2.

  The temperature detection unit 30 inputs two oscillation circuits OSC1 and OSC2 having different temperature coefficients, and clock pulses CL1 and CL2 from the oscillation circuits OSC1 and OSC2, compares the clock pulses CL1 and CL2, and compares them. It is comprised by the judgment part 60 which converts into temperature information from a frequency difference and outputs the temperature detection signal P12.

  The positive terminal of the solar cell 5 is connected to the GND of the electronic timepiece 1, and the negative terminal of the solar cell 5 is connected to one terminal of the charge control switch S2 of the charge control unit 3 as the generated voltage VHD. The other terminal of the switch S2 is connected to the cathode of the diode D1 of the system control unit 2.

  On the other hand, the positive terminal of the Li ion secondary battery 4 is connected to the GND of the electronic timepiece 1, and the negative terminal is connected to the connection point between the anode of the diode D1 and one terminal of the operation stop switch S1 as the storage voltage VBT. The stored voltage VBT is also connected to the operation stop control circuit 13 of the timepiece IC 10. Further, the other terminal of the operation stop switch S1 is supplied to the timepiece IC 10 as the storage voltage VBT ′. The GND is connected to the watch IC 10 and the charge control IC 20. Here, if GND of the electronic timepiece 1 is set as a reference potential, the generated voltage VHD and the stored voltage VBT are negative potential voltages.

  As shown in FIG. 1, the storage voltage VBT is the storage voltage itself of the Li ion secondary battery 4, and the storage voltage VBT 'is a voltage obtained by subtracting the voltage drop related to the opening / closing of the operation stop switch S1 from the voltage. It becomes. If the operation stop switch S1 is configured with a switch having a small contact resistance, there is almost no difference between the storage voltage VBT and the storage voltage VBT ′ when the operation stop switch S1 is ON.

[Description of Operation of Basic Concept of the Present Invention: FIG. 1]
Next, the outline of the operation of the basic concept of the present invention will be described with reference to FIG.
In FIG. 1, when the solar cell 5 is irradiated with light, an electromotive force is generated, and a generated voltage VHD having a predetermined voltage value is generated. If the ambient temperature is within the allowable charging temperature range, the charging control unit 3 turns on the charging control switch S2 by the charging control signal P13, so that the Li ion secondary battery 4 and the diode D1 are connected from the positive terminal of the solar battery 5 via GND. A current path is formed to the charge control switch S2 and the negative terminal of the solar cell 5, the charging current Icg from the solar cell 5 flows to the Li ion secondary battery 4, and the Li ion secondary battery 4 is charged.

  On the other hand, the operation stop control circuit 13 of the timepiece IC 10 turns on the operation stop switch S1 when the Li ion secondary battery 4 is charged to some extent and the storage voltage VBT becomes equal to or higher than a predetermined voltage. The storage voltage VBT ′ from the Li ion secondary battery 4 is supplied via As a result, the crystal oscillation circuit 11 of the timepiece IC 10 oscillates and outputs a reference clock P10 of 32,768 Hz. The clock circuit 12 inputs the reference clock P10, measures the time, and drives a display unit (not shown) to display the time. If the solar battery 5 continues to be irradiated with light, the Li ion secondary battery 4 is continuously charged and the timepiece IC 10 can continue to operate and display the time.

  Next, when the solar cell 5 is no longer irradiated with light, the generated voltage VHD, which is the electromotive force of the solar cell 5, decreases and charging to the Li ion secondary battery 4 stops. The stored voltage VBT is supplied by the stored power, and the timepiece IC 10 continues to operate. In this state, if the Li ion secondary battery 4 is not charged for a long period of time, the electric power stored in the Li ion secondary battery 4 is reduced, the stored voltage VBT is lowered, and the operation of the watch IC 10 is not performed. Become stable.

  The operation stop control circuit 13 monitors the storage voltage VBT, outputs a stop signal P11 at a predetermined voltage value before the operation of the timepiece IC 10 becomes unstable, and turns off the operation stop switch S1. As a result, the power supply to the timepiece IC 10 is stopped, so that the electronic timepiece 1 can stably stop the operation without causing an unstable malfunction.

  On the other hand, if even a small amount of light is irradiated on the solar cell 5 and the generated voltage VHD is supplied to the charge control IC 20, the temperature detection unit 30 of the charge control IC 20 will detect each of the two built-in oscillation circuits OSC1 and OSC2. Temperature information is calculated from the frequency difference between the clock pulses CL1 and CL2. The determination unit 60 of the temperature detection unit 30 determines whether the acquired temperature information is within the charge permission temperature range of the Li ion secondary battery 4 and outputs a temperature detection signal P12.

  When the temperature detection signal P12 is input and the temperature is out of the charge permission temperature range, the charge control circuit 70 of the charge control IC 20 outputs the charge control signal P13 and turns off the charge control switch S2. When the charging control switch S2 is turned off, the charging current Icg flowing to the Li ion secondary battery 4 is interrupted, and charging to the Li ion secondary battery 4 is forcibly stopped. This operation can prevent charging at a temperature outside the allowable charging temperature range.

As described above, the basic concept of the present invention is configured such that the system control unit 2 and the charge control unit 3 are separated, and the timepiece IC 10 of the system control unit 2 is operated by the storage voltage VBT of the Li ion secondary battery 4. The charging control IC 20 of the charging control unit 3 is operated by the power generation voltage VHD from the solar cell 5.
For this reason, even if the storage voltage VBT of the Li ion secondary battery 4 decreases and the timepiece IC 10 stops operating, if the solar cell 5 is irradiated with a slight amount of light and the generated voltage VHD is generated, the charge control IC 20 Can perform charge control while continuing operation and detecting temperature.

  That is, by using the present invention, it is possible to safely use a Li-ion secondary battery that can cause abnormal heat generation, ignition, rupture, etc. if charging is continued in an environment outside the allowable charging temperature range. It can be done.

[Configuration of Electronic Timepiece of Embodiment: FIG. 2]
Next, the configuration of the embodiment will be described with reference to FIG.
The features of the present embodiment include a configuration of the basic concept described above (see FIG. 1), and a configuration in which practically necessary control is further added. Each of the storage voltage VBT and the generated voltage VHD is added to the charge control unit. A voltage detection circuit for detecting the voltage value of the voltage and a booster circuit for boosting the generated voltage VHD.
Since most of the configuration of the embodiment is common to the basic concept (FIG. 1), the same elements are denoted by the same reference numerals and redundant description is omitted, and the configuration of the charging control unit is mainly described. explain.

  In FIG. 2, reference numeral 100 denotes the electronic timepiece of the embodiment. The electronic timepiece 100 is a solar timepiece system similar to the electronic timepiece 1 of the basic concept, and includes a system control unit 2 that controls the timepiece, a charge control unit 110 that controls charging of the power storage means, and Li ions as power storage means. It is comprised by the secondary battery 4, the solar cell 5 as a power generation means, etc. In the present embodiment as well, the display unit for displaying the time is not directly related to the invention and is not shown.

  Since the configuration of the system control unit 2 of the electronic timepiece 100 and the connection of the Li ion secondary battery 4 are the same as the configuration of the basic concept (see FIG. 1), description thereof is omitted. Similarly to the configuration of the basic concept, the system control unit 2 and the charge control unit 110 are separated into two, and the system control unit 2 is operated by the storage voltage VBT from the Li ion secondary battery 4 and charged. The control unit 110 operates with the generated voltage VHD that is the power generated by the solar cell 5.

  The positive terminal of the solar cell 5 is connected to the GND of the electronic timepiece 100 in the same manner as the basic concept, and the negative terminal of the solar cell 5 is connected to a booster circuit 150 and a voltage detection circuit 140, which will be described later, as the generated voltage VHD. Entered. Further, since the connection between the operation stop switch S1 and the diode D1 included in the system control unit 2 is the same as the basic concept, description thereof is omitted here.

The charging control unit 110 of the electronic timepiece 100 is configured by a charging control IC 120. As for the internal configuration of the charge control IC 120, a voltage detection circuit 140 and a booster circuit 150 are added to the configuration of the basic concept charge control IC 20.
The temperature detection unit 30 is the same as the basic concept, and the charge control circuit 130 is configured by adding a voltage detection signal P15 described later to the basic concept charge control circuit 70.

In the example illustrated in FIG. 2, the clock pulse CL1 of the oscillation circuit OSC1 is used as the system clock SYSCLK that operates the entire charging control IC 120. As will be described later, it is also used for clock pulses for sampling operation of the voltage detection circuit 140 and for boosting operation of the boosting circuit 150.
Of course, another oscillation circuit may be provided to generate the system clock. However, if the clock pulse CL1 of the oscillation circuit OSC1 is used, this is not necessary, and the circuit scale can be reduced and the power consumption can be reduced.

The voltage detection circuit 140 of the charging control IC 120 operates by inputting the system clock SYSCLK, and inputs the stored voltage VBT from the Li ion secondary battery 4 and the generated voltage VHD from the solar battery 5 to generate the voltage detection signal P15. Output. Note that the voltage detection circuit 140 may be configured to detect either the stored voltage VBT or the generated voltage VHD depending on the specifications of the electronic timepiece 100. The details of the voltage detection circuit 140 will be described later.

  The charge control circuit 130 receives the voltage detection signal P15 together with the temperature detection signal P12, and outputs the charge control signal P13 based on the voltage information of the Li ion secondary battery 4 and the solar battery 5 together with the temperature information. Details of the charging control circuit 130 will be described later.

  The booster circuit 150 is disposed in place of the charge control switch S2 (see FIG. 1) having the basic concept, and receives the system clock SYSCLK as a booster clock pulse, and generates a generated voltage VHD that is power generated by the solar cell 5. The voltage is doubled and output as a boosted voltage VHD2. The booster circuit 150 is controlled to be boosted and stopped by the charge control signal P13. Details of the booster circuit 150 will be described later.

  The boosted voltage VHD2 output from the booster circuit 150 is connected to the cathode of the diode D1, whereby the Li-ion secondary battery 4, the diode D1, the booster circuit 150, and the solar battery 5 pass through the positive terminal of the solar battery 5 and GND. A current path is formed to the negative terminal of the battery, and the charging current Icg flows into the Li ion secondary battery 4 to be charged.

  By arranging the booster circuit 150, the Li-ion secondary battery 4 can be charged by being boosted by the booster circuit 150 even when the voltage value of the generated voltage VHD that is the electromotive force of the solar battery 5 is low. . In particular, the booster circuit 150 is effective when the space for installing the solar battery 5 is small and the number of cells of the solar battery 5 must be reduced. In the present embodiment, the booster circuit 150 boosts the generated voltage VHD by a factor of 2, but the number of boosting steps is arbitrary and is determined according to the specifications of the Li ion secondary battery 4 and the solar battery 5. The

  Further, if the number of cells of the solar battery 5 can be arranged in accordance with the storage voltage VBT of the Li ion secondary battery 4, the booster circuit 150 may be omitted. In that case, the generated voltage VHD is set as in the basic concept configuration. What is necessary is just to arrange | position the charge control switch S2 which interrupts | blocks.

Moreover, although the solar cell has been described as an example of the power generation means, it is of course not limited to this, and any device that converts natural energy into electric energy may be used.
For example, it is possible to use electromagnetic induction type power generation means for generating electric power by moving the electronic timepiece main body to change its kinetic energy to the movement of a rotary weight. It is also possible to use a thermoelectric generator that generates heat by converting the thermal energy into an electrical signal using a Peltier element or the like by heat applied to the electronic timepiece.

  In general, both electromagnetic induction power generation means and thermoelectric generation means have a low power generation voltage. Depending on the configuration, the generated voltage may be less than 1.0V. However, even if such a power generation means is employed, the low power generation voltage VHD can be boosted by using the booster circuit 150, so that the Li ion secondary battery 4 can be sufficiently charged.

  Next, details and operations of each element of the charging control unit 110 according to the present embodiment will be described with reference to FIGS.

[Description of Basic Configuration and Temperature Characteristics of Oscillation Circuit of Temperature Detection Unit: FIGS. 3 and 4]
As described above, the temperature detection unit 30 includes the two oscillation circuits OSC1 and OSC2, compares the clock pulses, and converts temperature information from the difference between the oscillation frequencies.
Since the basic configurations of the two oscillation circuits OSC1 and OSC2 are the same, an example of the basic configuration of the oscillation circuit OSC1 will be described with reference to the circuit diagram of FIG.

In FIG. 3, the oscillation circuit OSC1 is configured by a well-known CR oscillation circuit, and is configured by six inverter circuits IN1 to IN6, a buffer circuit BF1, a resistor R1, and a capacitor C1.

  As shown in the figure, the six inverter circuits IN1 to IN6 are connected in series, and the output terminal of the inverter circuit IN6 feeds back to the input terminal of the inverter circuit IN1 via the capacitor C1. Further, the connection point between the output terminal of the inverter circuit IN3 and the input terminal of the inverter circuit IN4 and the input terminal of the inverter circuit IN1 are connected via a resistor R1 as shown in the figure.

  Then, the output terminal of the inverter circuit IN6 at the final stage is connected to the buffer circuit BF1, the waveform is shaped by the buffer circuit BF1, and is output as the clock pulse CL1 and the system clock SYSCLK. The oscillation circuits OSC1 and OSC2 are driven by the power generation voltage VHD from the solar cell 5 (see FIG. 2).

  The basic configurations of the two oscillation circuits OSC1 and OSC2 are the same, but are designed so that the temperature coefficients of the respective oscillation frequencies are different. For example, the temperature coefficient of the oscillation frequency can be changed by utilizing the fact that the temperature coefficient of the resistor itself can be changed by changing the material of the resistor R1 of the oscillation circuit OSC1.

That is, the material of the resistor R1 of the oscillation circuit OSC1 is polysilicon formed on a semiconductor substrate (hereinafter referred to as Poly-Si). That is, the resistor R1 is composed of a Poly-Si resistor.
The Poly-Si resistor has a negative temperature characteristic as is known. Then, a positive temperature coefficient can be obtained for the oscillation frequency of the oscillation circuit OSC1. This is because the oscillation frequency increases as the resistance value of the resistor R1 decreases.

The material of the resistor R1 ′ (referred to as such here for convenience) of the oscillation circuit OSC2 is a diffused resistor formed in the semiconductor substrate. That is, the resistor R1 ′ is configured by a diffused resistor.
The diffusion resistance has a positive temperature characteristic as is known. Then, a negative temperature coefficient can be obtained for the oscillation frequency of the oscillation circuit OSC2. This is because the oscillation frequency decreases as the resistance value of the resistor R1 ′ increases.

FIG. 4 is a graph schematically showing an example of temperature characteristics of the two oscillation circuits OSC1 and OSC2.
4A, as described above, the resistor R1 of the oscillation circuit OSC1 is configured by a Poly-Si resistor so that the oscillation circuit OSC1 has a positive temperature coefficient, while the resistor R1 ′ of the oscillation circuit OSC2 is provided. In this example, the oscillation circuit OSC2 has a negative temperature coefficient by using a diffusion resistor.
In this case, since the temperature coefficients of the oscillation frequencies of the two oscillation circuits OSC1 and OSC2 are opposite to each other, the frequency difference Δf can change relatively greatly with respect to the change in the ambient temperature T.

  The frequency difference Δf with respect to the change in the ambient temperature T tends to improve the detection sensitivity for the reason described later, but the temperature coefficients of the two oscillation circuits OSC1 and OSC2 are the same (for example, positive). It doesn't matter. One example is the example shown in FIG.

FIG. 4B shows a case where the temperature coefficients of the two oscillation circuits OSC1 and OSC2 are both positive, and the slope of the change in the oscillation frequency with respect to the ambient temperature T is different.
In this case, since the inclination directions of the changes in the oscillation frequency are the same (that is, the temperature coefficient has the same polarity), the frequency difference Δf with respect to the change in the ambient temperature T is the example shown in FIG. Compared to relatively small changes.

  Here, since the temperature detection unit 30 converts the temperature information from the frequency difference Δf shown in FIG. 4, the temperature change can be detected with higher sensitivity when the frequency difference Δf is largely changed with respect to the ambient temperature T. As shown in FIG. 4A, it is preferable that the temperature coefficients of the oscillation frequencies of the two oscillation circuits OSC1 and OSC2 are opposite to each other. However, if the sensitivity is too good, the stability of the temperature detection may decrease. Therefore, when priority is given to the stability of the temperature detection, as shown in FIG. 4B, the two oscillation circuits OSC1 and OSC2 The temperature coefficient of oscillation frequency should be set to the same polarity.

[Description of Configuration of Judgment Unit of Temperature Detection Unit: FIG. 5]
Next, the structure of the determination part 60 of the temperature detection part 30 is demonstrated using FIG.
In FIG. 5, the temperature detection unit 30 includes the two oscillation circuits OSC1 and OSC2 and the determination unit 60 as described above. The oscillation circuit OSC1 is always operating, and the oscillation circuit OSC2 is intermittently operating. The oscillation frequency of the oscillation circuit OSC1 is set lower than the oscillation frequency of the oscillation circuit OSC2 (see FIG. 4).
As a result, even when the oscillation circuit OSC1 is always operating, the oscillation frequency is low, so that the power consumption of the charging control IC 120 can be kept low, and the charging control IC 120 can be operated with a slight electromotive force from the solar cell 5. it can.

The determination unit 60 includes a window generation circuit 61, a temperature sense counter 62, a comparison circuit 63, and a plurality of tables of temperature data T1 to Tn input to the comparison circuit 63. These temperature data are stored in a nonvolatile storage device (not shown).
The window generation circuit 61 of the determination unit 60 receives the clock pulse CL1 from the oscillation circuit OSC1 as a reference clock, and outputs a detection pulse P20 generated based on the clock pulse CL1.

The detection pulse P20 is supplied to the temperature sense counter 62 and the oscillation circuit OSC2. The oscillation circuit OSC2 is controlled to be turned on and off by the detection pulse P20. The oscillation circuit OSC2 starts and continues oscillation only when the detection pulse P20 is logic “1”, and oscillates when the detection pulse P20 is logic “0”. Stops. That is, the oscillation circuit OSC2 performs an intermittent operation by the detection pulse P20.
Therefore, in the oscillation circuit OSC2, a circuit that operates intermittently by the detection pulse P20 is added to the circuit configuration of the oscillation circuit OSC1 shown in FIG. 3, but the oscillation circuit that performs such an operation is well known. Therefore, the description is omitted.

  The temperature sense counter 62 receives the clock pulse CL2 from the oscillation circuit OSC2 and the detection pulse P20, and outputs the count data Nt by counting the number of clock pulses CL2 when the detection pulse P20 is logic “1”. To do. Here, as described above, since the detection pulse P20 is generated by the clock pulse CL1, the period during which the detection pulse P20 is logic “1” has a length according to the temperature characteristic of the oscillation circuit OSC1.

  Further, since the frequency of the clock pulse CL2 counted by the temperature sense counter 62 changes depending on the temperature characteristics of the oscillation circuit OSC2, the value of the count data Nt represents the frequency difference Δf between the two oscillation circuits OSC1 and OSC2. Therefore, the count data Nt can be converted into the ambient temperature T.

The comparison circuit 63 receives the count data Nt, compares the numerical value of the count data Nt with the numerical values of the temperature data T1 to Tn of a plurality of tables, and detects the temperature detection signal P according to the comparison result.
12 is output.
For example, when the charge permission temperature range of the Li ion secondary battery 4 is, for example, 0 ° C. to + 45 ° C., the temperature data T1 is set to a table value corresponding to 0 ° C., which is the lower limit value of the temperature range, and the temperature data T2 is set to The value in the table corresponds to + 45 ° C. of the upper limit value of the temperature range.

When the value of the count data Nt is less than the temperature data T1, the comparison circuit 63 sets the temperature detection signal P12 to logic “0”, the value of the count data Nt is equal to or higher than the temperature data T1, and is less than the temperature data T2. When the count data Nt is equal to or higher than the temperature data T2, the temperature detection signal P12 is set to logic "0".
By this operation, the comparison circuit 63 sets the temperature detection signal P12 to logic “1” when the ambient temperature T obtained from the count data Nt is within the charge permission temperature range of 0 ° C. to + 45 ° C., and the charge permission temperature range. If it is outside, the temperature detection signal P12 can be set to logic "0".

  In addition, if the temperature data T1-Tn is one kind of Li ion secondary battery to be used, it is only necessary to set the temperature data of the lower limit and the upper limit of the charging permission temperature range of the battery. It consists only of T1 and T2. However, when a plurality of types of Li ion secondary batteries to be used are assumed and the allowable charging temperature ranges of the respective batteries are different, the lower and upper limits of the allowable charging temperature ranges of the plurality of Li ion secondary batteries expected to be used Temperature data is prepared, and the temperature data is preferably switched according to the Li ion secondary battery to be used.

Switching of the temperature data may be performed by button operation or non-contact communication after the watch is manufactured, or may be performed by patterning so as to switch the circuit in the middle of manufacturing, and those methods are already known. Since this can be used, the description here is omitted.
Note that the determination unit 60 of the temperature detection unit 30 is also driven by the generated voltage VHD from the solar cell 5.

[Explanation of operation of temperature detector: FIGS. 5, 6, and 7]
Next, details of the temperature detection operation of the temperature detection unit 30 will be described with reference to FIGS. 5, 6, and 7.
Here, for easy understanding of the operation description, FIG. 6 shows an operation example of the temperature detection unit 30 when the temperature dependency of the oscillation circuit OSC1 is large and the temperature dependency of the oscillation circuit OSC2 is small, and FIG. An operation example of the temperature detection unit 30 when the temperature dependency of the circuit OSC2 is large and the temperature dependency of the oscillation circuit OSC1 is small is shown.

  6A shows an example of the operation of the temperature detector 30 when the ambient temperature T (see FIG. 4) is low, and FIG. 6B shows the temperature detection when the ambient temperature T is normal temperature. FIG. 6C shows an example of the operation of the temperature detector 30 when the ambient temperature T is high. Here, since the oscillation circuit OSC1 is highly temperature dependent, the frequency of the clock pulse CL1a when the ambient temperature T is low is low, and the frequency of the clock pulse CL1b when the ambient temperature T is normal temperature is medium. The frequency of the clock pulse CL1a when the temperature T is high increases. Further, since the temperature dependency of the oscillation circuit OSC2 is small, it is assumed that the oscillation frequency of the clock pulse CL2 hardly changes.

In the example shown in FIG. 6A, since the oscillation frequency of the clock pulse CL1a of the oscillation circuit OSC1 is low, the length Tw1 (period of logic “1”) of the detection pulse P20a generated based on the clock pulse CL1a is become longer. Here, as described above, the temperature sense counter 62 counts the number of pulses of the clock pulse CL2 of the oscillation circuit OSC2 when the detection pulse P20a is logic “1”. Therefore, the count data Nt that is the count value is large. Thus, the value 16 is output as an example.

  In the example shown in FIG. 6B, since the oscillation frequency of the clock pulse CL1b of the oscillation circuit OSC1 is medium, the length Tw2 (logic “1”) of the detection pulse P20b generated based on the clock pulse CL1b is used. Period) is medium. Since the temperature sense counter 62 counts the number of pulses of the clock pulse CL2 of the oscillation circuit OSC2 when the detection pulse P20b is logic “1”, the count data Nt that is the count value is in the middle. The value 12 is output.

  In the example shown in FIG. 6C, since the oscillation frequency of the clock pulse CL1c of the oscillation circuit OSC1 is high, the length Tw3 (period of logic “1”) of the detection pulse P20c generated based on the clock pulse CL1c. ) Becomes shorter. Since the temperature sense counter 62 counts the number of clock pulses CL2 of the oscillation circuit OSC2 when the detection pulse P20c is logic “1”, the count data Nt that is the count value decreases, and as an example, the value 8 Is output.

As described above, when the temperature dependency of the oscillation circuit OSC1 is large and the temperature dependency of the oscillation circuit OSC2 is small, the length Tw of the detection pulse P20 changes according to the ambient temperature T. Since the count data Nt output from the above changes according to the ambient temperature T, the value of the count data Nt can be converted into the ambient temperature T.
Then, the comparison circuit 63 of the determination unit 60 compares the value of the count data Nt with the temperature data T1 to Tn, outputs the temperature detection signal P12, and controls the above-described charge control circuit 70.

Next, the operation of the temperature detection unit 30 when the oscillation circuit OSC2 has a large temperature dependence will be described with reference to FIG.
In FIG. 7, since it is assumed that the temperature dependency of the oscillation circuit OSC1 is small, the frequency of the clock pulse CL1 hardly changes. Since the detection pulse P20 is generated based on the clock pulse CL1, the length Tw (period of logic “1”) of the detection pulse P20 is substantially constant with respect to the ambient temperature T.

  Here, the clock pulse CL2a of the oscillation circuit OSC2 shows a state when the ambient temperature T (see FIG. 4) is low, and its oscillation frequency becomes higher due to the low temperature, and the temperature sense counter 62 is as described above. Since the number of pulses of the clock pulse CL2a of the oscillation circuit OSC2 is counted when the detection pulse P20 is logic “1”, the count data Nt that is the count value increases, and a value 16 is output as an example.

  Further, the clock pulse CL2b of the oscillation circuit OSC2 shows a state when the ambient temperature T is normal temperature, and the oscillation frequency becomes middle at normal temperature, and the temperature sense counter 62 indicates that the detection pulse P20 is logic “1”. Sometimes, since the number of pulses of the clock pulse CL2b of the oscillation circuit OSC2 is counted, the count data Nt that is the count value is intermediate, and the value 12 is output as an example.

  Further, the clock pulse CL2c of the oscillation circuit OSC2 shows a state when the ambient temperature T is high, the oscillation frequency becomes low due to the high temperature, and the temperature sense counter 62 indicates that the detection pulse P20 is logic “1”. Since the number of pulses of the clock pulse CL2c of the oscillation circuit OSC2 is counted, the count data Nt that is the count value decreases, and the value 8 is output as an example.

  As described above, when the temperature dependency of the oscillation circuit OSC2 is large and the temperature dependency of the oscillation circuit OSC1 is small, the oscillation frequency of the clock pulse CL2 of the oscillation circuit OSC2 changes according to the ambient temperature T. Since the count data Nt output from the sense counter 62 changes according to the ambient temperature T, the value of the count data Nt can be converted into the ambient temperature T.

Here, the actual temperature characteristics of the two oscillation circuits OSC1 and OSC2 can be set so that the temperature coefficients are opposite to each other as shown in FIG. Can be combined with FIG. 6 and FIG.
That is, as shown in FIG. 6, the length Tw of the detection pulse P20 is changed according to the change in the ambient temperature T, and the oscillation circuit OSC2 is changed according to the change in the ambient temperature T as shown in FIG. Since the oscillation frequency of the clock pulse CL2 can also be changed, the value of the count data Nt output from the temperature sense counter 62 of the temperature detection unit 30 reliably captures the change in the ambient temperature T and accurately obtains the temperature information. Can be acquired.

[Description of Configuration and Operation of Voltage Detection Circuit: FIG. 8]
Next, the configuration of the voltage detection circuit 140 built in the charge control IC 120 will be described with reference to FIG.
Note that the voltage detection circuit 140 may be configured to detect either the stored voltage VBT or the generated voltage VHD, or to detect both the stored voltage VBT and the generated voltage VHD.
When detecting both voltages, two voltage detection circuits 140 are arranged in the charge control IC 120. Even when two voltage detection circuits 140 are arranged, the individual circuit configurations of the voltage detection circuits 140 are the same. In the description, the case where there is one voltage detection circuit 140 will be described as an example.

  In FIG. 8A, the voltage detection circuit 140 includes a comparator circuit 141, a D input flip-flop circuit 142 (hereinafter abbreviated as D-FF 142), a detection switch S21, divided resistors R2 and R3, a timing generation circuit 143, and the like. Composed. Although a circuit for generating the reference voltage VREF is also included, the circuit for generating the reference voltage VREF can be generated from a known regulator circuit or the like, and thus description and illustration thereof are omitted here.

The timing generation circuit 143 receives the system clock SYSCLK from the oscillation circuit OSC1, and generates and outputs an enable signal En and a latch clock signal L-CK based on the system clock SYSCLK.
The voltage detection circuit 140 performs a sampling operation with the enable signal En and the latch clock signal L-CK, which are the two timing signals, and detects the storage voltage VBT or the generated voltage VHD.

  One terminal of the detection switch S21 is connected to GND, the other terminal is connected to one terminal of the dividing resistor R2, the other terminal of the dividing resistor R2 and one terminal of the dividing resistor R3 are connected, and the dividing resistor is connected. The other terminal of R3 is connected to the storage voltage VBT when the voltage detection circuit 140 detects the voltage value of the storage voltage VBT, and to the generation voltage VHD when the voltage detection circuit 140 detects the voltage value of the generation voltage VHD. Connected. That is, the other terminal of the dividing resistor R3 serves as an input terminal for a voltage detected by the voltage detection circuit 140.

  The control terminal G21 for controlling ON / OFF of the detection switch S21 is connected so that an enable signal En from the timing generation circuit 143 is input. The enable signal En enables the operation of the comparator circuit 141 (operation permission). ) Is also used as a signal. The detection switch S21 is turned ON when the control terminal G21 is logic “1”.

One input terminal of the comparator circuit 141 is connected to the reference voltage VREF, the other input terminal is connected to the connection point A between the dividing resistors R2 and R3, and the output terminal of the comparator circuit 141 is the D input terminal of the D-FF 142. Connected to.
Here, the comparator circuit 141 determines whether the stored voltage VBT divided by the dividing resistors R2 and R3 or the voltage value of the generated voltage VHD (that is, the voltage value at the connection point A) exceeds or does not exceed the reference voltage VREF. Determination is made and the comparator signal P14 is output from the output terminal.

Here, if the voltage detection circuit 140 detects a voltage drop of the storage voltage VBT of the Li ion secondary battery 4, the division ratio between the division resistors R <b> 2 and R <b> 3 is a predetermined voltage value to be detected and the reference voltage VREF. The division ratio of the dividing resistors R2 and R3 is determined from the ratio of Further, if the voltage detection circuit 140 detects a voltage drop of the power generation voltage VHD of the solar battery 5, the division ratio between the division resistors R2 and R3 is determined from the ratio between the predetermined voltage value to be detected and the reference voltage VREF. decide.
Thereby, the comparator circuit 141 can detect the voltage drop of the storage voltage VBT or the power generation voltage VHD.

The clock terminal CL of the D-FF 142 receives the latch clock signal L-CK, and the output terminal Q outputs the voltage detection signal P15. Although not shown, the positive power source of the comparator circuit 141 and the D-FF 142 is connected to the circuit GND, and the negative power source is connected to the generated voltage VHD. That is, the voltage detection circuit 140 is driven by the power generation voltage VHD from the solar cell 5.
When the voltage detection circuit 140 is composed of two circuits for detecting both the storage voltage VBT and the generated voltage VHD, a built-in timing generation circuit 143 and a circuit for generating a reference voltage VREF (not shown) ) Can also be shared.

Next, the operation of the voltage detection circuit 140 will be described with reference to the timing chart of FIG.
In FIG. 8B, the logic “1” is output from the timing generation circuit 143 for a predetermined period of the enable signal En based on the system clock SYSCLK at a predetermined repetition period. The comparator circuit 141 operates in an enabled state during a period in which the enable signal En is logic “1”. Further, since the detection switch S21 is turned on by the enable signal En, a current flows from the GND to the division resistors R2 and R3 via the detection switch S21, and a division voltage is generated at the connection point A. That is, the operating current flows through the comparator circuit 141 and the dividing resistors R2 and R3 only when the enable signal En becomes logic “1”, so that the voltage detection circuit 140 can operate with less power.

Here, the comparator circuit 141 compares the reference voltage VREF with the voltage value at the connection point A during the enable period, and if the comparison result indicates that the voltage value at the connection point A is lower than the reference voltage VREF, the comparator of logic “0”. A signal P14 is output, and if the voltage value at the connection point A is higher than the reference voltage VREF, a comparator signal P14 of logic “1” is output.
Note that the comparator signal P14 is valid only during a period in which the enable signal En for operating the comparator circuit 141 is logic “1”, and is indefinite in other periods.

  The comparator signal P14 is connected to the D input terminal of the D-FF 142, and the D-FF 142 receives the latch clock signal L-CK input to the clock terminal CL at the timing t1 when the logic signal “1” falls from the logic “1”. The comparator signal P14 is read and stored, and the logic of the comparator signal P14 stored from the output terminal Q is output as the voltage detection signal P15. Here, since the latch clock signal L-CK is output in synchronization with the enable signal En as shown in the period when the enable signal En is logic “1”, the D-FF 142 has the comparator signal P14 in the valid period. Can be read reliably.

  Thereby, the D-FF 142 can output the logic of the newly read comparator signal P14 from the output terminal Q as the voltage detection signal P15 at the timing t1 when the latch clock signal L-CK falls. That is, the voltage detection circuit 140 performs a sampling operation at a predetermined cycle based on the system clock SYSCLK from the oscillation circuit OSC1, and can detect a voltage drop of the stored voltage VBT or the generated voltage VHD.

  Incidentally, the voltage detection sampling of the voltage detection circuit 140 may not be performed in accordance with the system clock SYSCLK. This is because sampling may be performed at a detection timing determined by the system. In such a case, sampling may be performed using a known timing generation circuit that determines the timing.

[Description of Charging Control Circuit: FIG. 9]
Next, the configuration of the charging control circuit 130 built in the charging control IC 120 will be described with reference to FIG.
In FIG. 9, the charging control circuit 130 includes a three-input AND circuit 131 and an inverter circuit 132. The 3-input AND circuit 131 inputs the temperature detection signal P12 from the temperature detection unit 30, the voltage detection signal P15 from the voltage detection circuit 140, and the system clock SYSCLK, and outputs the charge control signal P13. The inverter circuit 132 receives the charge control signal P13 and outputs an inverted charge control signal P13 ′. Note that the charging control circuit 130 is also driven by the generated voltage VHD from the solar battery 5.

  With this configuration, the charge control circuit 130 is configured such that the system clock SYSCLK is a 3-input AND circuit when the temperature detection signal P12 becomes the charge permission temperature range and logic “1” and the voltage detection signal P15 becomes logic “1”. After passing 131, the system clock SYSCLK appears in the charge control signal P13, and the inverted signal of the system clock SYSCLK appears from the inverted charge control signal P13 ′.

  In other words, the charge control signal P13 and the inverted charge control signal P13 ′ output the system clock SYSCLK and its inverted clock under the condition that the temperature detection signal P12 and the voltage detection signal P15 are both logic “1”. . The system clock SYSCLK output as the charge control signal P13 and the inverted charge control signal P13 ′ becomes a boost clock pulse for driving a booster circuit 150 described later. In FIG. 2 described above, the signal line connecting the charge control circuit 130 and the booster circuit 150 is shown as the charge control signal P13. Specifically, as shown in FIG. 9, the inverted charge control signal P13 ′ is also included. Yes.

  Further, as described above, when the voltage detection circuit 140 is configured by two circuits for detecting both the storage voltage VBT and the generated voltage VHD, two voltage detection signals P15 are also output. The AND circuit 131 is configured as a 4-input AND circuit. In this case, the system clock SYSCLK is output as the charge control signal P13 under the condition that the two voltage detection signals P15 are both logic “1” and the temperature detection signal P12 is logic “1”.

[Description of Booster Circuit Configuration and Operation: FIG. 9]
Next, the configuration of the booster circuit 150 built in the charge control IC 120 will be described with reference to FIG.
The booster circuit 150 is a charge pump booster circuit that boosts the input voltage twice. In FIG. 9, the booster circuit 150 includes four boost switches S11 to S14 and two boost capacitors C11 and C12. Here, the boost switches S11 to S14 include control terminals G11 to G14 for controlling ON and OFF, but when a logic “0” is input to the control terminals G11 to G14, the switches are turned ON, “1”
It is designed so that the switch is turned off when is input.

The step-up switches S11 to S14 are connected in series as shown. That is, one terminal of the boost switch S11 is connected to the GND of the circuit, the other terminal of the boost switch S11 is connected to one terminal of the boost switch S12, and thereafter connected in series to the boost switches S13 and S14. The boosted voltage VHD2 is output from the other terminal of the boost switch S14.
The control terminals G11 and G13 of the boost switches S11 to S14 receive the charge control signal P13, and the control terminals G12 and G14 receive the inverted charge control signal P13 ′.

  One terminal of the boost capacitor C11 is connected to GND, and the other terminal of the boost capacitor C11 is connected to a connection point between the boost switches S12 and S13, and the generated voltage VHD from the solar cell 5 is input to this connection point. . Further, one terminal of the boost capacitor C12 is connected to a connection point between the boost switches S11 and S12, and the other terminal of the boost capacitor C12 is connected to a connection point between the boost switches S13 and S14.

Next, an outline of the operation of the booster circuit 150 will be described with reference to FIG.
In FIG. 9, when the temperature detection signal P12 is logic “1” and the voltage detection signal P15 is logic “1”, the system clock SYSCLK and its inverted clock are supplied from the charge control circuit 130 to the charge control signal P13 and inverted charge. It is output as a control signal P13 '. The charge control signal P13 is input to the control terminals G11 and G13 of the boost switches S11 and S13, and the inverted charge control signal P13 ′ is input to the control terminals G12 and G14 of the boost switches S12 and S14. Thus, the boost switches S11 and S13 and the boost switches S12 and S14 are switched ON and OFF at high speed at the timing of the system clock SYSCLK.

With this operation, when the boost switches S11 and S13 are turned on, both of the boost capacitors C11 and C12 are charged with the power of the generated voltage VHD, and when the next boost switches S12 and S14 are turned on, the boost capacitor Since C11 and C12 are connected in series, a voltage obtained by boosting the generated voltage VHD by a factor of two is output from the boosted voltage VHD2. In this description, since an example of double boosting is used, the boosted voltage is referred to as VHD2.
Since the operation of turning on and off the boost switches S11 to S14 is repeated at high speed at the timing of the system clock SYSCLK, the boost voltage VHD2 stably outputs a voltage twice as large as the generated voltage VHD. The boosted voltage VHD2 is supplied to the Li ion secondary battery 4 via the diode D1, and charging is performed by flowing the charging current Icg.

  Thus, the booster circuit 150 uses the system clock SYSCLK from the oscillation circuit OSC1 of the temperature detection unit 30 as the boost clock pulse for switching the boost switches S11 to S14. For this reason, since it is not necessary to newly generate a boost clock pulse, the circuit scale of the charging control IC 120 can be reduced, and an increase in power consumption can be prevented.

When either the temperature detection signal P12 or the voltage detection signal P15 is logic “0”, the charge control signal P13 from the charge control circuit 130 is logic “0”, and the inverted charge control signal P13 ′ is logic “1”. "Is maintained. As a result, the booster circuit 150 is stopped and the booster switch S14 to which the reverse charge control signal P13 ′ is input is continuously turned OFF, so that the boosted voltage VHD2 is opened, and the potential becomes zero volts, and the Li ion two Charging the secondary battery 4 is prohibited.
That is, the charge control circuit 130 operates the booster circuit 150 only when the temperature detection signal P12 and the voltage detection signal P15 are both active (logic “1”) to charge the Li ion secondary battery 4, If either the temperature detection signal P12 or the voltage detection signal P15 is logic “0”, the booster circuit 150 is stopped to inhibit charging.
In other words, the booster circuit 150 has the function of the charge control switch S2 shown in FIG.

Next, an outline of the overall operation of the charge control unit 110 of the present embodiment will be described.
Here, in the charge control, when the charge control unit 110 detects the voltage drop of one of the storage voltage VBT and the power generation voltage VHD and performs the charge control (operation example 1), the charge control unit 110 performs the storage control voltage VBT. Therefore, the operation example 1 and the operation example 2 will be described separately below, because charging control is performed by detecting a voltage drop of both the power generation voltage VHD and the power generation voltage VHD (operation example 2). Note that the operation of the system control unit 2 of the embodiment is the same as the operation of the basic concept described above (see FIG. 1), and thus description thereof is omitted here.

[Description of Operation Example 1 of Charging Control of Embodiment: FIG. 10]
An outline of an operation example 1 of the charging control unit 110 according to the embodiment will be described with reference to an operation flow of FIG.
Here, the charge control operation example 1 is an operation in which the charge control unit 110 is driven by the solar battery 5 and performs charge control by detecting one of the storage voltage VBT and the power generation voltage VHD and detecting the temperature. The charge control unit 110 refers to the block diagram of FIG. 2, and the internal circuit configuration and operation of the charge control IC 120 refer to FIGS. In the operation example 1, the voltage detection circuit 140 shown in the block diagram of FIG. 2 is configured to detect either the stored voltage VBT or the generated voltage VHD.

  In FIG. 10, the voltage detection circuit 140 of the charging control unit 110 driven by the solar battery 5 performs a sampling operation at a predetermined cycle based on the system clock SYSCLK, and the storage voltage VBT of the Li ion secondary battery 4 or the solar battery The voltage value of the power generation voltage VHD of the battery 5 is compared with the internal reference voltage VREF, and whether or not the storage voltage VBT or the power generation voltage VHD is equal to or higher than a predetermined value is output as a voltage detection signal P15 (step ST1). Here, when the storage voltage VBT or the generated voltage VHD is equal to or higher than a predetermined value, the voltage detection signal P15 is output as logic “1”, and when it is lower than the predetermined value (that is, the voltage is reduced), The voltage detection signal P15 is output as logic “0”.

  Next, the charging control unit 110 determines whether or not the voltage value of the storage voltage VBT or the generated voltage VHD is equal to or greater than a predetermined value. If the voltage value is equal to or greater than the predetermined value, the process proceeds to the next step ST3. The process proceeds to step ST6 (step ST2).

  Here, when the charge control unit 110 determines that the storage voltage VBT is less than a predetermined value (voltage detection signal P15: logic “0”), the Li ion secondary battery 4 is in an overdischarged state, and in this state When the recharge is performed, the Li ion secondary battery 4 is deteriorated or broken. Therefore, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits the charge, and sets the Li Deterioration or breakage of the ion secondary battery 4 is prevented (step ST6).

  Similarly, when the charging control unit 110 determines that the generated voltage VHD is less than a predetermined value (voltage detection signal P15: logic “0”), the two oscillation circuits of the temperature detecting unit 30 that operates at the generated voltage VHD. In the OSC 1 and the OSC 2, when the generated voltage VHD is remarkably lowered, the oscillation frequency becomes voltage-dependent and an error occurs in temperature detection. Therefore, accurate charge control within the allowable charge temperature range cannot be performed. Therefore, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits charging, and protects the Li ion secondary battery 4 (step ST6).

  When the charge control unit 110 determines that the voltage value of the storage voltage VBT or the generation voltage VHD is equal to or greater than a predetermined value (voltage detection signal P15: logic “1”), the voltage of the storage voltage VBT or the generation voltage VHD Since the value is normal and the Li ion secondary battery 4 can be charged, the temperature detection unit 30 detects the ambient temperature (step ST3). Here, the temperature detection unit 30 detects the ambient temperature from the frequency difference Δf (see FIG. 4) between the two oscillation circuits OSC1 and OSC2.

  Next, the determination unit 60 of the temperature detection unit 30 compares the detected ambient temperature within the charge permission temperature range and outputs a temperature detection signal P12, and the charge control unit 110 determines the temperature detection signal P12. If it is within the charging permission temperature range (temperature detection signal P12: logic “1”), the process proceeds to the next step ST5, and if it is outside the charging permission temperature range (temperature detection signal P12: logic “0”). The process proceeds to step ST6 (step ST4).

  Here, if the charging control unit 110 determines in step ST4 that the ambient temperature is outside the allowable charging temperature range, if the charging is performed at the ambient temperature, the Li ion secondary battery 4 is abnormally heated, ignited, or worst-cased. In this case, since there is a possibility of causing a state such as a rupture, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits charging, and sets the Li ion secondary battery 4 Protect (step ST6).

  On the other hand, if the charging control unit 110 determines in step ST4 that the ambient temperature is within the allowable charging temperature range, the charging control circuit 130 outputs a charging control signal P13 of logic “1”, and the boosting circuit 150 is turned on. The boosted voltage VHD2 is output by operating, and charging of the Li ion secondary battery 4 is started (step ST5). The charging control circuit 130 also outputs the inverted charging control signal P13 ′ as described above, but a description thereof is omitted here.

  When charging is started, the charging control unit 110 repeats the operation from step ST1 in the next sampling cycle, and detects the storage voltage VBT or the generated voltage VHD (step ST1) and the temperature detection (step ST3). It continues and charge control is continued so that the charge to the Li ion secondary battery 4 may be implemented safely.

  In addition, even if charging is stopped in step ST6, the charging control unit 110 performs voltage detection and temperature detection again at the next sampling timing, so that the operation from step ST1 is repeated as the operation flow. If the start condition is satisfied, the process proceeds to step ST5 and charging is started.

  In addition, although the voltage detection (ST1) and the temperature detection (ST3) are sequentially performed in the operation flow of FIG. 10, these two detection operations may be performed simultaneously (in parallel).

  The first priority of detection of the storage voltage VBT and the power generation voltage VHD is detection of voltage drop of the storage voltage VBT. This is because when the Li ion secondary battery 4 is in an overdischarged state, there is a risk that the Li ion secondary battery 4 will be damaged if recharged. For this reason, it is preferable that the charge control operation example 1 is configured to prioritize detection of the voltage drop of the storage voltage VBT and to detect the voltage drop of the storage voltage VBT.

  As described above, since the charge control operation example 1 detects either the storage voltage VBT or the power generation voltage VHD, only one voltage detection circuit 140 is required, and the control can be simplified. Either one of avoiding overdischarge of the Li ion secondary battery 4 and avoiding malfunction of the temperature detection unit 30 due to a decrease in the generated voltage VHD is selected.

[Description of Operation Example 2 of Charge Control of Embodiment: FIG. 11]
Next, the outline of the operation example 2 of the charge control unit 110 according to the embodiment will be described with reference to the operation flow of FIG.
Here, the operation example 2 of the charge control unit is an operation in which the charge control unit 110 is driven by the solar battery 5 and performs charge control by detecting both the storage voltage VBT and the power generation voltage VHD and detecting the temperature. .

  The charge control unit 110 refers to the block diagram of FIG. 2, and the internal circuit configuration and operation of the charge control IC 120 refer to FIGS. In the operation example 2, the voltage detection circuit 140 shown in the block diagram of FIG. 2 includes two voltage detection circuits 140 that detect the voltages of the storage voltage VBT and the generated voltage VHD.

  In FIG. 11, the voltage detection circuit 140 for detecting the storage voltage VBT of the charge control unit 110 performs a sampling operation at a predetermined cycle based on the system clock SYSCLK, and sets the voltage value of the storage voltage VBT of the Li ion secondary battery 4 to a predetermined value. Compared with the value, the result is output as a voltage detection signal P15 (step ST11). Here, when the storage voltage VBT is equal to or higher than a predetermined value, the voltage detection signal P15 is output as logic “1”, and when it is lower than the predetermined value (that is, the voltage is reduced), the voltage detection signal P15 is output. Is output as logic “0”.

  Next, the charging control unit 110 determines whether or not the voltage value of the storage voltage VBT is greater than or equal to a predetermined value. If the voltage value is greater than or equal to the predetermined value, the process proceeds to the next step ST13, and if less than the predetermined value, the process proceeds to step ST18. (Step ST12).

  Here, when the charge control unit 110 determines that the storage voltage VBT is less than a predetermined value (voltage detection signal P15: logic “0”), the Li ion secondary battery 4 is in an overdischarged state, and in this state When the recharge is performed, the Li ion secondary battery 4 is deteriorated or broken. Therefore, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits the charge, and sets the Li Deterioration or breakage of the ion secondary battery 4 is prevented (step ST18).

  If the charge control unit 110 determines in step ST12 that the stored voltage VBT is equal to or higher than a predetermined value (voltage detection signal P15: logic “1”), the voltage detection circuit 140 that detects the generated voltage VHD is a system The sampling operation is performed at a predetermined cycle based on the clock SYSCLK, the voltage value of the power generation voltage VHD of the solar cell 5 is compared with a predetermined value, and the result is output as the voltage detection signal P15 (step ST13). Here, when the generated voltage VHD is equal to or higher than the predetermined value, the voltage detection signal P15 is output as logic “1”, and when it is lower than the predetermined value (that is, the voltage is reduced), the voltage detection signal P15 is output. Is output as logic “0”.

  Next, the charging control unit 110 determines whether or not the voltage value of the generated voltage VHD is equal to or greater than a predetermined value. If the voltage value is equal to or greater than the predetermined value, the process proceeds to the next step ST15. (Step ST14).

  Here, when the charge control unit 110 determines that the generated voltage VHD is less than a predetermined value (voltage detection signal P15: logic “0”), the two oscillation circuits of the temperature detection unit 30 that operates at the generated voltage VHD. In OSC1 and OSC2, when the power generation voltage VHD is significantly reduced, voltage dependency occurs in the oscillation frequency and an error occurs in temperature detection. Therefore, charge control within the accurate charge permission temperature range cannot be performed. Therefore, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits charging, and protects the Li ion secondary battery 4 (step ST18).

In addition, when the charge control unit 110 determines that the voltage values of both the storage voltage VBT and the power generation voltage VHD are equal to or greater than a predetermined value, the voltage values of the storage voltage VBT and the power generation voltage VHD are normal, and Li Since the ion secondary battery 4 can be charged, the temperature detection unit 30 detects the ambient temperature (step ST15). Here, the temperature detection unit 30 detects the ambient temperature from the frequency difference Δf (see FIG. 4) between the two oscillation circuits OSC1 and OSC2.

  Next, the determination unit 60 of the temperature detection unit 30 compares the detected ambient temperature within the charge permission temperature range and outputs a temperature detection signal P12, and the charge control unit 110 determines the temperature detection signal P12. If it is within the charge permission temperature range (temperature detection signal P12: logic “1”), the process proceeds to the next step ST17, and if it is outside the charge permission temperature range (temperature detection signal P12: logic “0”). The process proceeds to step ST18 (step ST16).

  Here, if it is determined that the ambient temperature is outside the allowable charging temperature range, charging at the ambient temperature causes the Li ion secondary battery 4 to generate abnormal heat generation, ignition, or, in the worst case, explosion. Since there is a possibility, the charge control circuit 130 sets the charge control signal P13 to logic “0”, stops the booster circuit 150, prohibits charging, and protects the Li ion secondary battery 4 (step ST18).

  On the other hand, when the charge control unit 110 determines in step ST16 that the temperature is within the allowable charging temperature range, the charge control circuit 130 outputs the charge control signal P13 of logic “1”, operates the booster circuit 150, and Li Charging of the ion secondary battery 4 is started (step ST17). When charging is started, the charging control unit 110 repeats the operation from step ST11 in the next sampling cycle, detects the storage voltage VBT and the generated voltage VHD (steps ST11 and ST13), and detects the temperature (step ST15). ) Is continuously performed, and the charging control is continued so that the charging of the Li ion secondary battery 4 can be performed safely.

  In addition, even if charging is stopped in step ST18, the charging control unit 110 performs voltage detection and temperature detection again at the next sampling timing, so that the operation from step ST11 is repeated as the operation flow. If the conditions for starting charging are satisfied, the process proceeds to step ST17 and charging is started.

  In the operation flow of FIG. 11, the storage voltage VBT detection (ST11), the generated voltage VHD detection (ST13), and the temperature detection (ST15) are sequentially performed, but these three detection operations are performed simultaneously (in parallel). You may implement.

  As described above, the charge control operation example 2 detects both the storage voltage VBT and the power generation voltage VHD, so that two voltage detection circuits 140 are arranged, and the charge control is slightly more complicated than the operation example 1. However, since both the over discharge avoidance of the Li ion secondary battery 4 and the avoidance of malfunction of the temperature detection unit 30 due to the decrease in the generated voltage VHD are implemented, the Li ion secondary battery Charging can be performed more safely.

  As described above, the embodiment of the present invention has been described by showing two operation examples. However, in any of the operation examples, the system control unit 2 and the charge control unit 110 are separated, and the clock of the system control unit 2 is displayed. The IC 10 is operated by the storage voltage VBT of the Li ion secondary battery 4, and the charge control IC 120 of the charge control unit 110 is operated by the power generation voltage VHD from the solar battery 5. For this reason, even if the storage voltage VBT of the Li ion secondary battery 4 decreases and the timepiece IC 10 stops operating, even if the solar battery 5 is irradiated with a slight amount of light and the generated voltage VHD is generated, the charge control IC 120 Can perform charge control while continuing operation and detecting temperature.

As described above, in the present invention, the system control unit (timepiece IC) that controls the operation of the timepiece and the charge control unit (charge control IC) that controls the charging of the secondary battery operate independently of each other, and the Li ion Charge control to the secondary battery can be performed. As a result, the Li-ion secondary battery can be kept safely within the allowable charging temperature range at any time without interrupting the charging of the Li ion secondary battery. Can be provided.

  In addition, the charge control unit is equipped with a temperature detection unit that obtains temperature information from the difference in oscillation frequency between the two oscillation circuits, so that highly accurate temperature detection that is less susceptible to variations due to circuit characteristics and fluctuations in power supply voltage can be realized. Thus, it is possible to safely charge the Li ion secondary battery that has a limited charging permission temperature range.

  In addition, since the charge control unit can detect the overdischarge of the Li ion secondary battery from the stored voltage of the Li ion secondary battery and stop the charging operation, it is possible to charge the Li ion secondary battery that is in an overdischarged state. Risk can be eliminated. In addition, since the charge control unit can detect the power generation voltage of the solar cell and stop the charging operation when the power generation amount of the solar cell is low, the temperature detection unit of the charge control unit can Therefore, the risk that the charging control malfunctions can be eliminated.

  In addition, according to the present invention, a Li-ion secondary battery having a high capacity and a low internal resistance can be used as a power source for an electronic timepiece, so that the timepiece can be used for a long time after charging and a relatively large current is required. The time information receiving operation of the radio-controlled timepiece can be stably performed.

  The embodiment of the present invention exemplifies a configuration in which the system control unit and the charge control unit are separated into two IC chips to separate the power sources that drive the respective circuits. However, the present invention is not limited to this configuration. Although not shown, the system control unit and the charge control unit may be configured as a single chip, and the power sources of the system control unit and the charge control unit may be electrically separated within the chip.

Further, as already described, the power generation means is not limited to the solar cell, and can have a known power generation mechanism.
Furthermore, the block diagrams, circuit diagrams, flowcharts, and the like described in the embodiments are not limited and can be arbitrarily changed without departing from the gist of the present invention.

  The electronic timepiece of the present invention can be widely used for a solar electronic timepiece equipped with a high-capacity Li-ion secondary battery and an electronic timepiece having a radio wave correction function for automatically correcting the time.

DESCRIPTION OF SYMBOLS 1,100 Electronic timepiece 2 System control part 3,110 Charge control part 4 Lithium ion secondary battery (Li ion secondary battery)
5 Solar cell 10 Clock IC
DESCRIPTION OF SYMBOLS 11 Crystal oscillation circuit 12 Clock circuit 13 Operation stop circuit 20, 120 Charge control IC
30 Temperature Detection Unit 60 Judgment Unit 70, 130 Charge Control Circuit 140 Voltage Detection Circuit 150 Booster Circuit S1 Operation Stop Switch S2 Charge Control Switch D1 Backflow Prevention Diode (Diode)
OSC1, OSC2 Oscillator circuit VBT, VBT 'Storage voltage VHD Power generation voltage VHD2 Boost voltage Icg Charging current CL1, CL2 Clock pulse SYSCLK System clock

Claims (1)

In an electronic timepiece comprising a power generation means, a power storage means having a limited charging permission temperature range, and a system control unit for controlling the operation of the timepiece,
The system control unit stops operating when the power stored in the power storage unit is equal to or lower than a predetermined value, operates with the power generated by the power generation unit, detects the temperature, and operates within the charging permission temperature range. A charge control unit for controlling to charge the power storage means;
The charge control unit includes a temperature detection unit having two oscillation circuits having different temperature characteristics from each other,
The temperature detection unit performs temperature detection by comparing clock pulses generated by both of the oscillation circuits,
Of the two oscillation circuits, one always operates and the other operates intermittently.
The oscillation circuit that is always operating has a lower oscillation frequency than the oscillation circuit that is operating intermittently,
The temperature detection unit counts the number of pulses of the clock pulse of the oscillation circuit that is intermittently operated by a detection pulse generated based on the clock pulse of the oscillation circuit that is always operating, and detects the temperature based on the result An electronic timepiece characterized by performing.

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