JP4075201B2 - Electronics - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device driven by a battery, and more particularly to an electronic device in which both a secondary battery and a primary battery can be used as a power source.
[0002]
[Prior art]
Conventionally, in the case of an electronic device configured to be relatively small for portable use, a storage unit that can store a battery is provided, and the device is operated by a power source from the battery stored in the storage unit. There are various types. In this case, there are various types of batteries that can use secondary batteries that can be repeatedly used by charging, in addition to primary batteries such as dry batteries.
[0003]
FIG. 6 shows an example of a power supply configuration of an electronic device driven by a conventional battery. One or a plurality of batteries 1 are configured such that a voltage Vin of a power source supplied from the battery is detected by a voltage detection circuit 2. Then, the power from the battery 1 is supplied to the DC / DC converter 4 via the switch 3, converted into a voltage for operating the device, and the converted output is supplied to the circuit unit 5 of the electronic device.
[0004]
Here, when the device is in operation, the switch 3 is controlled to be in an ON state, and when the battery voltage Vin detected by the voltage detection circuit 2 is monitored and becomes a voltage at which the device cannot be operated. Then, the switch 3 is turned off to stop the operation of the device. That is, as shown in FIG. 7, the battery voltage Vin has a characteristic of gradually decreasing as the device is used, and the battery voltage Vin detected by the voltage detection circuit 2 is lower than the preset end voltage Vend. If this happens, the switch 3 is turned off to stop discharging from the battery. In addition, there is a display that warns that the battery is exhausted on a display unit or the like provided in the device when the warning voltage Vwarn is slightly higher than the end voltage Vend.
[0005]
[Problems to be solved by the invention]
By the way, when a current is taken out from the battery in order to activate each circuit included in the electronic device, a phenomenon occurs in which the battery voltage Vin temporarily decreases due to the internal resistance of the battery and then recovers. FIG. 8 is a diagram showing an example of this state. When the device is started at a certain timing, the battery voltage Vin temporarily decreases by the voltage ΔV ₀ , and after that, over a period of time, the original battery voltage Vin is obtained. Return to.
[0006]
If there is a temporary drop in the battery voltage at the time of startup, for example, as shown in FIG. 8, there may occur a case where the voltage drops below the warning voltage Vwarn or the end voltage Vend only at the time of the temporary drop. When the voltage falls below the warning voltage Vwarn, a warning indicating that the battery has run out is displayed. When the voltage falls below the final voltage Vend, the switch 3 is turned off at that time, and the circuit operation stops. End up.
[0007]
As described above, even if the battery can still be used in practice, there is a problem in that it is determined that the battery has no remaining capacity and a warning or stop process is performed. Further, as shown in FIG. 8, the temporary drop of the voltage ΔV ₀ at the time of start-up occurs only when the internal resistance of the battery is large, and usually appears when a primary battery such as a dry battery is used. It is a phenomenon. For this reason, if the configuration is such that the battery voltage is determined after the time for the reduced voltage ΔV ₀ to recover, the problem due to the temporary decrease in the voltage ΔV ₀ can be solved. When a secondary battery that does not cause a temporary voltage drop is used, a process for starting the device with a low voltage is performed in the time until the determination, and the secondary battery is overdischarged. In the case of a device that can use both a primary battery and a secondary battery, it is not preferable.
[0008]
An object of the present invention is to enable good power control when a primary battery is used in a device that can use both a primary battery and a secondary battery.
[0009]
[Means for Solving the Problems]
The present invention provides an electronic device that can use both a primary battery and a secondary battery as a power source, and a plurality of load circuits in which power supply from the power supply unit is individually controlled, and the power supply unit. When the primary battery is used as the power source for the voltage measurement means that measures the voltage of the power supply with no detection resistor connected and with the detection resistor connected, and the voltage difference between both measured values measured by the voltage measurement means And a control means for determining that the primary battery is used as a power source and starting the supply of power to the plurality of load circuits at different timings. .
[0010]
According to the present invention, when the voltage difference between the power supply voltage with the detection resistor connected and the power supply voltage with no detection resistor connected measured by the voltage measuring means is large, it is used as a power supply. It is determined that the internal resistance of the battery is large, and control is performed to start the supply of power to the multiple load circuits provided in the device at different timings, and power is supplied to the circuits in the device in order. Will come to do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0012]
In this embodiment, the battery is applied to an electronic device used as a power supply source. As the battery used here, a primary battery such as a dry battery and a rechargeable secondary battery are used. Both can be used. As the secondary battery, a nickel metal hydride battery, a nickel cadmium battery, a lithium ion battery, or the like is used.
[0013]
FIG. 1 shows a power supply configuration of an electronic device in this embodiment. One or a plurality of batteries 11 mounted on this device are connected to a DC / DC converter 14 via a power switch 12 and a power supply control switch 13. Is converted to a voltage power source for operating the circuit, and the converted voltage power source is supplied to the circuit unit 20 which is a load circuit in the device. The power switch 12 is a switch that is manually operated by the user of this device (or a switch that is switched in conjunction with the power input operation of the user), and the power supply control switch 13 is turned on / off by the voltage detection circuit 15. Off is controlled. The voltage detection circuit 15 detects the voltage Vin of the battery 11 and controls the control of the power supply control switch 13 and the supply of power to each circuit in the circuit unit 20 based on the detection. It is.
[0014]
Here, a series circuit of a measurement resistor connection switch 16 and a measurement load resistor 17 is connected between a connection point between the power switch 12 and the power supply control switch 13 and the ground potential portion. The on / off state of the switch 16 is also controlled by the voltage detection circuit 15. As the battery 11, both a primary battery and a secondary battery can be used, but an external power source such as an AC adapter may be connected to the battery 11 instead of the battery.
[0015]
The circuit unit 20 that is a load circuit included in the electronic device is divided into a plurality of circuits 22a, 22b,... 22n (n is an arbitrary integer). Then, power is supplied from the DC / DC converter 14 via the power supply control switching elements 21a, 21b,... 21n (n is an arbitrary integer) for each circuit 22a, 22b,. It is. Each of the switching elements 21a to 21n is configured such that switching is individually controlled by control signals Ib1, Ib2,... Ibn supplied from the voltage detection circuit 15. Here, the transistors are used as the power supply control switching elements 21a to 21n, but other switching elements may be used.
[0016]
In this example, based on the battery voltage detected by the voltage detection circuit 15, the control state of each of the switching elements 21a to 21n when starting the device is changed. That is, when it is determined that a battery having a relatively large internal resistance (specifically, a primary battery) is used as a power supply, the switching elements 21a to 21n are turned on to shift the timing of supplying the power. Yes and so, if the relatively internal resistance less battery (specifically, a secondary battery) or external power source is determined to be used as a power source, by conducting the switching elements 21a~21n power The timings for supplying are matched. Details of the processing will be described later. In the voltage detection circuit 15, a final voltage Vend and a warning voltage Vwarn for comparison with a voltage value measured in advance are set. The end voltage Vend is a voltage value that makes it difficult to drive the circuit 20 at a voltage value lower than that, and the warning voltage Vwarn is slightly higher than the end voltage Vend. Further, a reference value Vjudge of the differential voltage for determining the type of battery is also set in advance in the voltage detection circuit 15.
[0017]
Next, power supply control processing by the circuit of this example will be described with reference to the flowchart of FIG. First, it is assumed that the user of this device performs a power-on operation and the power switch 12 is turned on (step S11). At this time, the voltage detection circuit 15 measures the battery voltage Vin while keeping the switches 13 and 16 in the OFF state (that is, in a state where no circuit is connected to the battery 11) (step S12). . The voltage value measured at this time is stored in the detection circuit 15 as Vin1.
[0018]
Next, the voltage detection circuit 15 measures the battery voltage Vin while the switch 16 is turned on and the measurement load resistor 17 is connected to the battery 11 (step S13). The voltage value measured at this time is also stored in the detection circuit 15 as Vin2. When this measurement is completed, the switch 16 is returned to the off state.
[0019]
When the measurement so far is completed, the voltage detection circuit 15 compares the voltage value Vin1 stored in step S12 with the end voltage Vend and the warning voltage Vwarn (step S14). In this comparison, when the voltage value Vin1 is the same as or lower than the end voltage Vend, the switch 13 remains in the OFF state and power is not supplied to the circuit unit 20 (step S15). In addition, when the voltage value Vin1 is higher than the end voltage Vend and lower than the warning voltage Vwarn, the switch 13 is turned on to supply power to the DC / DC converter 14 side, and to the display unit included in the device. A display to warn that the battery is almost exhausted is executed (step S16). Further, when the voltage value Vin1 is equal to or higher than the warning voltage Vwarn, the switch 13 is turned on to supply power to the DC / DC converter 14 side (step S17). In step S17, no warning operation is performed.
[0020]
Next, the voltage detection circuit 15 determines the difference voltage Vin1−Vin2 between the voltage value Vin1 and the voltage value Vin2, and determines whether or not the value of the difference voltage is lower than the reference value Vjudge (step S18). The reference value Vjudge here is a value between the difference voltage detected when a primary battery is used as the battery 11 and the difference voltage detected when a secondary battery is used as the battery 11. It is like that. Note that the differential voltage when using an external power supply is approximately the same value as the differential voltage when using a secondary battery.
[0021]
If the difference voltage falls below the reference value Vjudge in step S18, it is determined that the power source to be used is a secondary battery or an external power source (step S19), and each switching element 21a in the circuit unit 20 is determined. A control signal for simultaneously turning on to 21n is supplied, and power is simultaneously supplied to the load circuits 22a to 22n to start them (step S20).
[0022]
If the difference voltage is equal to or exceeds the reference value Vjudge in step S18, it is determined that the power source used is a primary battery (step S21), and each switching in the circuit unit 20 is performed. A control signal for sequentially turning on the elements 21a to 21n to turn them on is supplied, and power is sequentially supplied to the load circuits 22a to 22n to start them (step S22).
[0023]
Here, in the case of step S22, the state of shifting the timing for turning on the load circuits 22a to 22n will be described. Control signals Ib1, Ib2,... Ibn output from the switching elements 21a to 21n are, for example, The state shown in FIG. That is, since the ON state by supplying a control signal Ib1 to the switching element 21a in the first timing ta, after a predetermined time Delta] t ₁ has elapsed, the on-state by supplying a control signal Ib2 to the next switching element 21b, Subsequently, each switching element is sequentially turned on at each timing delayed by time Δt ₁ in order, and the control signal Ibn is supplied to the last switching element 21n to be turned on, so that all the load circuits 22a in the circuit unit 20 are turned on. Activate ~ 22n. Note that the circuit is actually activated and the signal processing is started at a timing tb when some time has elapsed since the last switching element 21n is turned on. This signal processing is started based on, for example, control of a system controller (not shown) in the device.
[0024]
Here, regarding the time Δt ₁ for shifting the timing for starting each circuit, when a primary battery is used as the battery 11, the battery voltage of the primary battery is almost restored after being lowered at the time of startup. Set the time until. Specifically, for example, the interval is about 100 ms.
[0025]
Thus, by performing start-up control when using the primary battery as a power source, the battery voltage at start-up becomes, for example, the state shown in FIG. That is, from the start of start at the timing ta, to repeat the process of returning after reduced by the voltage VD for each activating each circuit 22a~22n sequentially (i.e. time Δt _each). In this case, the voltage drop width VD can be made much smaller than the drop width when all the circuits in the circuit section 20 are activated simultaneously. Therefore, when a primary battery is used as a power source, even when the remaining amount of the battery is low, the remaining amount can be accurately detected, and the warning voltage and the end voltage can be detected almost correctly. Thus, it is possible to prevent the operation from being stopped when the end voltage is detected by using the remaining battery. Further, when a secondary battery or an external power source is used, such a process for shifting the activation timing is not performed, so that signal processing in a circuit in the device can be started quickly.
[0026]
Here, a specific example of an electronic device to which the processing of this embodiment is applied is shown in FIG. In this example, the present invention is applied to an electronic camera that electronically captures a still image or moving image of a subject and stores it in a memory. The electronic camera 100 converts image light incident through the photographing lens 101 into an electrical imaging signal by an imaging processing unit 102 including imaging means such as a CCD imager, and the imaging signal is converted by a signal processing circuit 103. A video signal having a predetermined format is stored in the external 106 via the internal memory 104. The external memory 106 is attached to the memory attachment unit 105.
[0027]
In addition, the liquid crystal display panel 108 is provided so that a captured image can be displayed by a video signal output from the signal processing circuit 103. In this case, a backlight 109 is attached to the liquid crystal display panel 108.
[0028]
These photographing processing, storage processing in the memory 106 and display processing on the liquid crystal display panel 108 are executed under the control of a central control unit (CPU) 107 constituted by a microcomputer. In addition, the electronic camera 100 includes a battery mounting unit 111, and the power control unit 112 supplies power to each circuit from a battery (primary battery or secondary battery) mounted on the mounting unit 111. It is. The power supply control unit 112 corresponds to the circuit shown in FIG. 1 such as the voltage detection circuit 15 in the above-described embodiment and the switching elements 21a to 21n and switches 13 and 16 controlled by the voltage detection circuit 15. .
[0029]
In the electronic camera configured as described above, when the power control unit 112 detects a secondary battery as the type of battery to be used, power is simultaneously supplied to each circuit at the time of startup. When the use of the primary battery is detected, for example, power is supplied to each circuit at startup in the following order. That is, power is first supplied to the central control unit 107, and thereafter, the imaging processing unit 102, the signal processing circuit 103, the internal memory 104, the liquid crystal display panel 108, the backlight 109, and the external memory 106 are powered in this order. Supply. By doing so, the operation state when starting up the electronic camera becomes good (that is, no problem due to a shift in the power supply state occurs).
[0030]
Note that the order of supplying the power described above is an example, and other orders may be used. Although the electronic camera has been described as an example here, it is needless to say that the power supply process of the present invention can be used for various other electronic devices that can be driven by a battery.
[0031]
【The invention's effect】
According to the present invention, the state of a battery or the like used as a power source is determined from the voltage difference between the two power source voltages in the voltage measuring unit, and the power supply to the plurality of load circuits included in the device is different. By performing the control that starts at the timing, for example, when a battery with a large internal resistance is used as a power source, power is sequentially supplied to the circuits in the device to operate, and each circuit in the device It is possible to avoid a significant drop in the power supply voltage due to simultaneous operation of the two. In addition, if it is determined from the voltage difference that a battery other than a battery with a large internal resistance is used as a power source, the control other than the battery with a large internal resistance can be used as a power source by not controlling the timing. When used, it is possible to perform quick control such as start of driving of the device based on the power supply voltage at that time.
[0032]
Further, in this electronic apparatus, the time of the difference in timing of supplying power to each load circuit is the time from when the power is supplied to one load circuit until the voltage of the power returns to the original voltage. Thus, the startup process can be performed while minimizing fluctuations in the power supply voltage at startup.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a power supply configuration according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an example of a power supply control process according to an embodiment of the present invention.
FIG. 3 is a timing diagram showing an example of a power supply control state according to an embodiment of the present invention.
FIG. 4 is a waveform diagram showing an example of a change in battery voltage according to an embodiment of the present invention.
FIG. 5 is a block diagram showing an example in which an electronic device according to an embodiment of the present invention is applied to an electronic camera.
FIG. 6 is a block diagram showing an example of a conventional power supply configuration.
FIG. 7 is a waveform diagram showing an example of battery voltage change.
FIG. 8 is a waveform diagram showing an example of battery voltage change at startup.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Battery, 12 ... Power switch, 13 ... Power supply control switch, 14 ... DC / DC converter, 15 ... Voltage detection circuit, 16 ... Measurement resistance connection switch, 17 ... Measurement load resistor, 20 ... Electronics Device circuit unit, 21a to 21n ... switching element for power supply control, 22a to 22n ... load circuit

Claims (2)

In an electronic device that can use both a primary battery and a secondary battery as a power source,
A power supply unit for supplying the power;
A detection resistor selectively connected to a power source obtained in the power supply unit;
A plurality of load circuits, each of which individually controls the supply of power from the power supply unit;
Voltage measuring means for measuring the voltage of the power source obtained in the power supply unit in a state where the detection resistor is not connected and in a state where the detection resistor is connected;
When the voltage of the difference between the two measured values measured by the voltage measuring means is larger than a reference value for detecting the case where the primary battery is used as a power source, it is determined that the primary battery is used as a power source. Te, the power supply to the plurality of load circuits, and a control means for starting at different timings electronic device. The electronic device according to claim 1,
An electronic device in which the difference in timing for supplying power to each of the load circuits is the time from when the power is supplied to one load circuit until the voltage of the power returns to the original voltage.

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