JP2006296019A - Power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply in which residual capacity of unit battery is detected accurately, while controlling the effect of voltage fluctuation between battery terminals by rapid current variation. <P>SOLUTION: The power supply comprises a series circuit of a switch circuit 102 and a capacitor 103 being connected in parallel with a power supply battery 101, circuits 105 and 110 for detecting the residual capacity of the power supply battery 101, and a control circuit 110 for turning the switch circuit 102 off when the residual capacity of the power supply battery 101 is detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power supply apparatus having a remaining capacity detection circuit that detects a remaining capacity of a battery.

  Currently, portable electronic devices that use a battery (a primary battery, a secondary battery, or a storage element similar to these) as a power source, such as a mobile phone or a portable audio device, are provided with the purpose of improving the convenience of the user. It is equipped with a function that measures the degree of wear of the battery using a remaining capacity detection mechanism and displays the usable time based on the result.

  As a remaining capacity detection method, a voltage measurement formula (Patent Documents 1 to 4) that determines a battery consumption degree from a voltage value by measuring a voltage between terminals of the battery, and a capacity value when not in use (in a secondary battery) There is a capacity integration formula (Patent Documents 5 to 7) that stores a charge current integrated value at the time of charging in a memory and determines the remaining capacity by subtracting the integrated value of the discharge current from the value. Therefore, the voltage measurement formula is adopted in many portable electronic devices.

  Hereinafter, a power supply device having a voltage measurement type remaining capacity detection function disclosed in Patent Document 4 will be briefly described with reference to FIGS. 4 and 5.

  As shown in FIG. 4, the power supply apparatus includes a battery unit 101, a current detection unit 102 including a coil 102a and a reed switch 102b, and a remaining capacity display unit 103 including diodes D1 to D4 that display the degree of wear of the battery unit 101. The current detection unit 104 includes voltage dividing resistors R1 and R2 and a comparator IC 104a, and the alarm display unit 105 includes a diode D0 that displays an alarm. 106 is a load. As shown in FIG. 5, the comparator IC 104a includes input terminals V1 and V2, a reference voltage source 104b, voltage dividing resistors r1 to r4, comparators CP1 to CP5, transistors T1 to T5, and output terminals Q1 to Q5. ing.

In the above configuration, when the load 106 operates, a current flows through the coil 102a, the reed switch 102b is turned on, and the battery unit 101, the load 106, and the remaining capacity detection unit 103 are connected in parallel. The voltage between the terminals of the battery unit 101 is divided by the voltage dividing resistors R1 and R2 and input to the input terminal V1 of the comparator IC 104a. A voltage level obtained by dividing the comparator IC 104a based on the voltage of the reference voltage source 104b is supplied to one input terminal of each of the comparators CP1 to CP5, and the input voltage V1 exceeds these reference voltages. Then, the transistors T1 to T5 connected to the output sides of the comparators CP1 to CP5 are turned on, and the diodes D1 to D4 in the remaining capacity display unit 103 are turned on. Focusing on the diodes D1 to D4, all of the diodes D1 to D4 are lit in the battery unit 101 before use. However, as the battery unit 101 is consumed, the diodes D4 → D3 → D2 → D1 are not lit. Specifically, all of the diodes D1 to D4 are not lit.
JP-A-7-98367 Japanese Patent Application Laid-Open No. 6-150981 JP-A-4-134279 JP-A-1-235169 Japanese Patent Laid-Open No. 7-241039 Japanese Patent Laid-Open No. 7-105985 JP-A-6-223879

  In an electronic device in which a sudden current fluctuation occurs during the operation of a load, there is a problem that the remaining capacity of the power source cannot be accurately detected by a voltage measurement formula due to the influence of the current fluctuation. For example, in the case of a camera, there is a risk that a steep load current may flow temporarily at the start of charging of a built-in strobe, at the start of film winding, and at the start of film winding. Not only is destroyed, but also misdetection of the remaining capacity is caused. This is because in the conventional remaining capacity detection technology, the voltage drop across the battery's internal resistance instantaneously becomes extremely large in a circuit that generates a large pulse current such as a rush current. This is because the voltage value becomes extremely lower than that at the time of stable operation. As already explained, in a power supply device equipped with a conventional voltage measurement type remaining capacity detection function, the voltage between the terminals of the battery is only compared with a preset voltage level. If the inter-terminal voltage falls below the voltage level that determines consumption, the battery is determined to be exhausted.

  As a countermeasure, there is a method of connecting a capacitor in parallel with the voltage measuring unit for detecting the battery, the load, and the remaining capacity. The capacitor is charged when the load is not operating or when it is in stable operation, and this current is supplied from the charge stored in the capacitor when the impedance on the load side becomes extremely low, such as when the motor is operating, causing sudden current fluctuations. Thus, the current from the battery can be stabilized and the fluctuation of the voltage between the terminals of the battery can be reduced, so that it is possible to prevent erroneous detection of the remaining capacity when a sudden current fluctuation occurs.

  However, even with such a configuration, the voltage between the terminals of the battery detected by the voltage measuring unit that detects the remaining capacity when the load is not operating or when the stable operation is performed is not an accurate value due to the influence of the impedance of the capacitor. . Therefore, in order to accurately detect the remaining capacity in an electronic device that may cause a sudden current fluctuation, it is necessary to have a technology that combines a means for reducing sudden current fluctuation and a means for accurately detecting the remaining capacity. It becomes.

(Object of invention)
An object of the present invention is to provide a power supply apparatus capable of accurately detecting the remaining capacity of a single battery while suppressing the influence of voltage fluctuation between battery terminals due to sudden current fluctuation.

  To achieve the above object, according to the present invention, a series circuit of a switch circuit and a capacitor connected in parallel with a power battery, a remaining capacity detection circuit for detecting the remaining capacity of the power battery, and the power battery When the remaining capacity is detected, the power supply device includes a control circuit that turns off the switch circuit.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can perform the exact remaining capacity detection about a battery single-piece | unit can be provided, suppressing the influence of the voltage fluctuation between battery terminals by rapid current fluctuation.

  The best mode for carrying out the present invention is as shown in Examples 1 to 3 described below.

  FIG. 1 is a block diagram showing a circuit configuration of an electronic apparatus according to Embodiment 1 of the present invention. The electronic device according to the first embodiment includes a power battery 101, a switch circuit 102, a rush current reducing capacitor 103, a switch circuit 104, a voltage dividing resistor 105 for detecting remaining capacity, a constant voltage circuit 106, a device main body circuit 107, and A motor which is an example of a load is provided. In the device main body circuit 107, an A / D conversion circuit 108, a display circuit 109 having a remaining capacity display unit and an alarm display unit, and a control circuit 110 are provided.

  The battery 101 includes a series circuit of a switch circuit 102 and a rush current reducing capacitor 103, a series circuit of a switch circuit 104 and a voltage dividing resistor 105 for detecting remaining capacity, a constant voltage circuit 106, a device main body circuit 107, and a motor 111. Are connected in parallel.

  The control circuit 110 provided in the device main body circuit 107 controls the entire electronic device in addition to the on / off control of the switch circuits 102 and 104.

  Specifically, the control circuit 110 manages the non-operation and operation of the electronic device, and at the same time controls the operation of the constant voltage circuit 106, and when the electronic device is in the non-operation state, Control is performed so that power is not supplied to the motor 111. Further, the control circuit 110 turns off the switch circuit 102 in order to reduce the leakage current of the capacitor 103 when the motor 111 is not driven. Further, when detecting the remaining capacity, in order to accurately detect the remaining capacity of the battery 101 alone, the switch circuit 102 is turned off to connect the capacitor 103 and the voltage dividing resistor 105 for detecting the remaining capacity. cut off. Further, when the motor 111 as a load is driven, the switch circuit 102 is turned on so that power is supplied from the battery 101 and the capacitor 103 to the motor 111, so that the current consumption in the motor 111 changes rapidly. Even in this case, the load variation of the battery 101 is reduced by compensating with the capacitor 103. The constant voltage circuit 106 supplies a stabilized output voltage from the battery 101 to a part of the electronic device.

  The A / D conversion circuit 108 provided in the device main body circuit 107 converts the voltage value of the battery 101 input via the voltage dividing resistor 105 into a digital value. In addition, the display circuit 109 displays the remaining capacity as an illustration or text according to the remaining capacity detection result, and also displays information related to the operation of the electronic device main body.

  Next, the operation of the main part of the electronic device having the above configuration will be described. When a signal indicating the start of operation of the electronic device is input to the control circuit 110, a control signal is sent from the control circuit 110 to the switch circuits 102 and 104, and the switch circuit 102 is turned on and the switch circuit 104 is turned off. When the switch circuit 102 is turned on, the battery 101 and the capacitor 103 are connected. Under this state, the battery 101, the capacitor 103, the constant voltage circuit 106, the device main body circuit 107, and the motor 111 as a load are connected in parallel, and the constant voltage circuit 106, the device main body circuit 107, and the motor 111 are connected to the power source 101 and Power is supplied from the capacitor 103.

  After a certain period of time has passed without the signal indicating the load operation start signal being input to the control circuit 110 after the electronic device has started to operate, a control signal is sent from the control circuit 110 to the switch circuits 102 and 104, and the switch circuit 102 is turned off and the switch circuit 104 is turned off. Thereby, since the connection between the capacitor 103 and the device main body circuit 107 and the motor 111 as a load is disconnected, the leakage current of the capacitor 103 is reduced.

  When a signal indicating the start of remaining capacity detection is input to the control circuit 110, a control signal is sent from the control circuit 110 to the switch circuits 102 and 104, the switch circuit 102 is turned off, and the switch circuit 104 is turned on. As a result, the voltage value between the terminals of the battery 101 divided by the voltage dividing resistor 105 for detecting the remaining capacity is input to the A / D conversion circuit 108, where it is A / D converted and the digital voltage value data is controlled. Sent to circuit 110. Then, the control circuit 110 compares the measured voltage value data with the operation prohibition voltage value set in advance in the internal memory, outputs information on the remaining capacity to the display circuit 109, and displays it on the remaining capacity display section. Let Further, when the measured voltage value data is equal to or lower than the operation prohibition voltage, an alarm indicating the operation prohibition is displayed on the alarm display portion of the display circuit 109, and at the same time, the driving of the motor 111 is prohibited.

  As described above, when the remaining capacity detection of the voltage measurement type is performed, it is possible to measure the voltage between the terminals of the power source 101 alone by disconnecting the capacitor 103 connected in parallel to the battery 101 by the switch circuit 102. Thus, the remaining capacity can be detected accurately using the voltage measurement method.

  When a signal indicating the start of driving of the motor 111 is input to the control circuit 110, a control signal is sent from the control circuit 110 to the switch circuits 102 and 104, the switch circuit 102 is turned on, and the switch circuit 104 is turned off. The motor 111 is driven. At this time, if there is a sudden change in current consumption such as a rush current in the motor 111, the current is compensated by the capacitor 103, and the load fluctuation of the battery 101 is suppressed.

  When a signal indicating the end of the operation of the electronic device is input to the control circuit 110, a control signal is sent from the control circuit 110 to the switch circuits 102 and 104, and the switch circuits 102 and 104 are turned off. Thereby, since the connection between the capacitor 103 and the device main body circuit 107 and the motor 111 is disconnected, the leakage current of the capacitor 103 is reduced.

  In FIG. 1, a motor is used as an example of a load. However, the present invention can be applied to other inductive and capacitive loads. When a specific example is a camera, the electronic device is a film feeding motor in a film driving circuit, an inductive load such as a shutter driving motor in a shutter operation circuit, or a capacitive such as a relatively large capacitor in a strobe charging circuit. The first embodiment can also be applied to a load or the like.

  According to the first embodiment, the series circuit of the switch circuit 102 and the capacitor 103 connected in parallel to the battery 101 that is a power source, the voltage dividing resistor 105 that detects the remaining capacity of the battery 101, and the remaining capacity of the battery 101. The electronic device includes a power supply device having a control circuit 110 that turns off the switch circuit 102 when detecting the above.

  As described above, when the remaining capacity is detected, the switch circuit 102 connected in series to the capacitor 103 is turned off, so that the voltage between the terminals of the battery 101 alone can be measured, and the battery Accurate remaining capacity detection for 101 is possible. That is, it is possible to accurately detect the remaining capacity of the voltage measurement type for a single battery while suppressing the influence of voltage fluctuation between battery terminals due to sudden current fluctuation.

  Further, by connecting the capacitor 103 in parallel to the battery 101, electric charge is accumulated in the capacitor 103 when the motor 111 as a load is not operating or stable operation, and the electric charge from the capacitor 103 is generated when sudden current fluctuation occurs. By supplying, the fluctuation of the voltage between the battery terminals can be reduced even when a sudden current fluctuation occurs.

  Furthermore, the switch circuit 102 is turned on when the motor 111 that is a load connected in parallel to the battery 101 and the capacitor 103 is driven. That is, when the motor 111 is not driven, the capacitor 103 is disconnected from the motor 111, and the capacitor 102 and the motor 111 are connected simultaneously with the start of driving of the motor 111. The leakage current from the capacitor 103 can be reduced.

  2 is a block diagram showing a circuit configuration of an electronic apparatus according to Embodiment 2 of the present invention. The same components as those in FIG.

  When the electric double layer capacitor 103a is used instead of the capacitor 103 of FIG. 1 in the configuration including the series circuit of the switch circuit and the capacitor connected in parallel with the battery as in the first embodiment, a low impedance Due to the characteristic of large capacity, the effect of compensation for a sudden change in current consumption in the motor 111 as a load is increased. On the other hand, if the electric double layer capacitor is connected to the battery in a state where it is not charged at all, an overcurrent flows at the moment of the start of charging, which may destroy the electric double layer capacitor or the battery. Therefore, the switch circuit 102 needs a function for adjusting the charging / discharging current.

  Therefore, in the second embodiment of the present invention, as shown in FIG. 2, when an electric double layer capacitor 103a is used as a capacitor, a switch circuit 102 that allows adjustment of charging / discharging current is incorporated. is there. That is, the electronic apparatus according to the second embodiment of the present invention includes a battery 101 and a power supply device including a series circuit including an electric double layer capacitor 103a and an NPN FET transistor 102a connected in parallel to the battery 101. It has.

  Next, only the operation of the electric double layer capacitor 103a and the switch circuit 102 (FET transistor 102a) connected in series to the electric double layer capacitor 103a in the electronic apparatus having the above configuration will be described.

  When the OFF signal is sent from the control circuit 110 to the gate terminal of the FET transistor 102a and the switch circuit 102 is turned off, a weak current due to the parasitic capacitance of the FET transistor 102a continues to flow. It is possible to charge with a small current.

  Simultaneously with the start of driving of the motor 111 as a load, an ON signal is sent from the control circuit 110 to the gate terminal of the FET transistor 102a, and when the switch circuit 102 is turned on, power is supplied to the motor 111 from the electric double layer capacitor 103a.

  According to the second embodiment, by using the switch circuit 102 (FET transistor 102a) capable of adjusting the charge / discharge current, the current for charging the electric double layer capacitor 103a can be regulated at the moment when the battery 101 is mounted. The electric double layer capacitor 103a having a large compensation effect for the current fluctuation of the motor 111 as a load and a large effect of suppressing the load fluctuation of the battery 101 can be used, and an accurate voltage measurement formula can be obtained as in the first embodiment. The remaining capacity can be detected.

  FIG. 3 is a block diagram showing a circuit configuration of an electronic apparatus according to Embodiment 3 of the present invention. The same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and details thereof are omitted.

  As described in the second embodiment, when an electric double layer capacitor is used as a capacitor, a switch circuit that enables adjustment of charging / discharging current is required in order to prevent overcurrent at the initial stage of charging. In the third embodiment of the present invention, as shown in FIG. 3, the switch circuit is changed only in that the switch circuit 102 has a configuration different from that of the second embodiment.

  Next, only the operation of the switch circuit 102 in the electronic apparatus having the above configuration will be described.

  When the motor 111 which is a load circuit is in a non-operating state, an ON signal is output from the control circuit 110 to the gate terminal of the NPN FET transistor 102b, and an OFF signal is applied to the gate terminal of the NPN FET transistor 102c. Then, the line between the FET transistor 102b and the current limiting resistor 102d becomes conductive. At this time, since the charging current of the electric double layer capacitor 103a is sufficiently weak due to the current limiting resistor 102d, the electric double layer capacitor 103a can be charged without an overcurrent flowing.

  Simultaneously with the start of driving of the motor 111, an OFF signal is sent from the control circuit 110 to the gate terminal of the FET transistor 102b, and an ON signal is sent to the gate terminal of the FET transistor 102c, and the line of the FET transistor 102c becomes conductive. Power is supplied to 111 from the power supply 101 and the electric double layer capacitor 103a.

  According to the above-described third embodiment, by using the switch circuit 102 (FET transistors 102b and 102c, current limiting resistor 102d) capable of adjusting the charging / discharging current, the electric double layer capacitor 103a is instantly attached to the battery 101. The electric double layer capacitor 103a which can regulate the current for charging the battery, has a large compensation effect for the current fluctuation of the motor 111 as a load, and has a large effect of suppressing the load fluctuation of the battery 101 can be used. As with, it is possible to accurately detect the remaining capacity of the voltage measurement type.

It is a block diagram which shows the circuit structure of the electronic device concerning Example 1 of this invention. It is a block diagram which shows the circuit structure of the electronic device concerning Example 2 of this invention. It is a block diagram which shows the circuit structure of the electronic device concerning Example 3 of this invention. It is a block diagram which shows the power supply device which has the conventional remaining capacity detection function. FIG. 5 is a circuit diagram illustrating details of the comparator IC in FIG. 4.

Explanation of symbols

101 battery 102 switch circuit 102a NPN type FET
102b NPN FET
102c NPN FET
102d Charging current limiting resistor 103 Capacitor 103a Electric double layer capacitor 104 Switch circuit 105 Voltage dividing resistor for remaining capacity detection 106 Constant voltage circuit 107 Device main body circuit 110 Control circuit 111 Motor as load

Claims (3)

A series circuit of a switch circuit and a capacitor connected in parallel with the power battery,
A remaining capacity detection circuit for detecting the remaining capacity of the power battery;
When performing the remaining capacity detection of the power battery, a control circuit that turns off the switch circuit;
A power supply device comprising:   The power supply device according to claim 1, wherein the control circuit turns on the switch circuit when driving a load connected in parallel to the power supply battery. The power supply apparatus according to claim 1, wherein the switch circuit is a switch circuit capable of adjusting a charge / discharge current, and the capacitor is an electric double layer capacitor.

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