JP3049920B2 - Battery level display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for displaying a remaining amount of a secondary battery which is a power source of a portable electronic device.

[0002]

2. Description of the Related Art Battery level display devices are generally of the battery voltage detection type which is advantageous in terms of cost, and most of them are built in a portable device body or a battery pack and used (for example,
JP-A-03-227772).

A conventional battery remaining amount display device will be described below with reference to the drawings. FIG. 5 is a configuration diagram showing a conventional battery remaining amount display device. In FIG. 5, reference numeral 1 denotes a secondary battery, and reference numeral 2 denotes a current detecting means which has a resistance of several tens to several hundreds of milliohms and is connected to the negative electrode of the secondary battery 1. Reference numeral 3 denotes a state detecting means, which comprises a charging detecting circuit 31 and an discharging detecting circuit 32 to which the output of the current detecting means 2 is input. Reference numeral 4 denotes a comparison voltage correction unit which receives an output of the current detection unit 2 and an output of the discharge detection circuit 32 as inputs. Reference numeral 5 denotes a battery voltage comparing means.
1, 52, 53, a voltage source 58 for generating a predetermined reference voltage at the input thereof, and resistors 54, 55, 56, 57 for generating a divided voltage of the battery voltage at the other input. And a voltage dividing circuit in which the output of the comparison voltage compensating means 4 is connected to the contact. Reference numeral 7 denotes a display means, a current control circuit 71 connected to the positive electrode of the secondary battery 1 and having the outputs of the charge detection circuit 31 and the discharge detection circuit 32 as control inputs, a switch 72 connected in parallel with the current control circuit 71, Current source 7 having an output of current control circuit 71 as input
3, LEDs 74, 75, 76 connected in series that emit light by the output current of the current source 73, and LEDs 74, 75, 7
A diode 7 whose anode is connected to the anode of 6
8, 79, 710, an oscillation circuit 77 having the output of the voltage comparator 51 as an input and the output connected to the cathode of a diode 78, and the output of the voltage comparators 52, 53 being the cathode of the diodes 79, 710, respectively. Consists of a connected configuration. Reference numeral 8 denotes a terminal to which a portable device main body or a charger is connected.

The operation of the conventional battery remaining amount display device configured as described above will be described below.

The current detecting means 2 converts the charge / discharge current of the secondary battery 1 into a very small voltage. The state detecting means 3 determines whether the state of the battery is charging, discharging, or standby based on the polarity and magnitude of the minute voltage output from the current detecting means 2. Specifically, when the negative electrode of the secondary battery is set to zero voltage, when the polarity of the minute voltage output from the current detecting means 2 is negative and the magnitude is equal to or greater than a predetermined value, the charge detection circuit 31 operates to indicate a charged state. (Hereinafter, the high voltage is referred to as H and the low voltage is also referred to as L), and when the polarity of the minute voltage is positive and the magnitude is equal to or greater than a predetermined value, the discharge detection circuit 32 operates and outputs H meaning a discharge state. Therefore, when the magnitude of the minute voltage is zero or less than a predetermined value, both the outputs of the charge detection circuit 31 and the discharge detection circuit 32 output L indicating a standby state. Comparison voltage correction means 4
Is used as a correction operation only when the output of the discharge detection circuit 32 is H, and a small current proportional to the minute voltage of the current detection means 2 is applied to the resistor 5.
The voltage is output to the contact point of the resistor 4 and the resistor 55, and the voltage at the voltage dividing point of the voltage dividing circuit is increased in proportion to the discharge current. As a result, the battery voltage when the voltage at the voltage dividing point falls below the predetermined reference voltage decreases in proportion to the increase in the discharge current. The battery voltage comparing means 5 detects the remaining battery level based on the battery voltage. The voltage comparator 51 has a remaining battery level of less than 10%, the voltage comparator 52 has a remaining battery level of less than 30%, and the voltage comparator 53 has a low battery level. 70% remaining
, The resistors 54, 55, 56,
57, a voltage source 58 for generating a reference voltage, and an output current of the comparison voltage correction means 4 are set. The display means 7 displays the remaining battery power according to the outputs of the voltage comparators 51, 52 and 53 by three Ls.
The ED is displayed in four stages with a bar-like lighting and one blinking.

The display means 7 will be described in further detail.
The current control circuit 71 supplies power to the current source 73 when the charge detection circuit is at the H output or the discharge detection circuit is at the H output. When the switch 72 is pressed, the switch becomes conductive and supplies power to the current source 73. Accordingly, the remaining battery level is displayed regardless of the switch 72 during charging and discharging, and the remaining battery level is displayed only when the switch 72 is pressed during standby. The current source 73 outputs a predetermined current to the LEDs 74, 75, 76 connected in series.
The oscillating circuit 77 oscillates at a one-second cycle duty ratio of 50% when the voltage comparator 51 outputs L, and outputs H when the voltage comparator 51 outputs H. Diodes 78, 79, 710
Is for preventing current from flowing into the LEDs 74, 75, 76 when the oscillation circuit 77 and the voltage comparators 52, 53 output H. When all of the voltage comparators 51, 52 and 53 output H, L
Since the output current of the current source 73 flows through the EDs 74, 75, and 76, three LEDs are turned on. When the battery voltage decreases and the voltage comparator 53 outputs L, the current of the LED 76 is cut off, the LED 76 is turned off, and two LEDs are turned on. When the battery voltage further decreases and the voltage comparators 52 and 53 output L, the LED 75,
76 is turned off and only the LED 74 is turned on. Further, when the battery voltage drops and the voltage comparator 51 also outputs L, the oscillating circuit 77 operates, and H and L are repeatedly output every 0.5 seconds, and the LED is output.
74 flashes.

FIG. 6 is a charge / discharge characteristic diagram in a conventional example. FIG. 6 shows the characteristics when the battery in a fully charged state is subjected to constant current discharge to a discharge end voltage after a pause, and then charged in a standby state. The battery voltage is represented by a solid line, and the remaining voltage is 70%, 30%, and 30%. 1
The 0% detection voltage is indicated by a dotted line, a one-dot broken line, and a two-dot broken line, and the remaining amount display level is indicated by an LED lighting state.

[0008]

However, in the above-described configuration, the correction of the divided voltage of the battery voltage comparing means 5 is performed by the discharge current. In the section where the change in the battery voltage is delayed with respect to the change in the discharge current, the display is different from the actual capacity, and the battery voltage rises as in section A (stop using the portable device).
In such a case, there is a problem that the display becomes smaller than the actual capacity, and when the battery voltage drops (the portable device is reused) as in the section B, the display becomes larger than the actual capacity.

The present invention solves the above problems,
It is an object of the present invention to provide a battery remaining amount display device in which a display level is constant regardless of stop or start of discharge or decrease or increase of discharge current.

[0010]

In order to achieve the above object, a battery remaining amount display device according to the present invention comprises a current detecting means for measuring the magnitude of a charging / discharging current, and whether the state of the battery is charging, discharging or standby. State detecting means for determining the input voltage of the voltage comparator, a comparison voltage correcting means for correcting the input voltage of the voltage comparator, a battery voltage comparing means comprising the voltage comparator for detecting a decrease in the battery voltage and its peripheral circuit, and the battery voltage It has a configuration including storage means for storing a decrease in battery voltage based on the output of the comparing means, and display means for displaying the remaining battery level based on the output of the storage means.

[0011]

The battery level display device of the present invention displays the remaining level based on the output of the storage means, not the battery voltage comparison means as in the prior art. This storage means has a function of stopping the storage operation by the output of the battery voltage comparison means when the battery voltage rises due to the decrease in the discharge current, and when the battery voltage rises due to the decrease in the discharge current (A in FIG. 6). In the section (section), the remaining amount is indicated by the storage before the discharge current is reduced. When the discharge current is increased (section B in FIG. 6), the battery voltage lowers slowly, and the battery voltage comparing means indicates a signal indicating a further reduction in capacity. Is not output and the remaining amount is displayed by the storage before the increase of the discharge current, so that the remaining amount display can be made constant regardless of the stop or start of the discharge or the decrease or increase of the discharge current.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention. In FIG. 1, reference numeral 6 denotes storage means, a battery voltage rise detection circuit 65 which outputs L when the battery voltage is equal to or higher than a predetermined rise rate, and outputs of each of the voltage comparators 51, 52, 53 and a battery voltage rise detection circuit. A set input circuit 64 composed of a two-input AND circuit having 65 outputs as inputs, RS flip-flops 61 and 62 having the output of the set input circuit 64 as a set input and the output of the charge detection circuit 31 as a reset input, 63. Reference numeral 7 denotes a display means, which is a current control circuit connected to the positive electrode of the secondary battery 1 and using the outputs of the charge detection circuit 31 and the discharge detection circuit 32 as control inputs.
1 and a switch 7 connected in parallel with the current control circuit 71.
2 and a current source 73 having an output of the current control circuit 71 as an input.
And LEDs 74, 75, 76 connected in series that emit light by the output current of the current source 73, and LEDs 74, 75, 76.
Diode 7 having its anode connected to its anode
8, 79, 710; an oscillating circuit 77 having an output of the RS flip-flop 61 and an output of the charge detection circuit 32 as inputs, and an output connected to the cathode of the diode 78;
The output of the RS flip-flops 62 and 63 is a diode 7
9, 710, respectively. Other configurations are basically the same as those in FIG. 5, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

The operation of the battery remaining amount display device of the present invention configured as described above will be described below.

First, the current detection resistor 2, the state detection means 3, the comparison voltage correction means 4, the battery voltage comparison means 5, and the display means 7
Since the operation is basically the same as that of the conventional example, detailed description thereof will be omitted, and the operation of the storage means 6 will be described.

The battery voltage rise detection circuit 65 outputs L when the battery voltage is equal to or higher than a predetermined rate, and outputs H when the battery voltage is lower than the predetermined rate. When the output of the battery voltage rise detection circuit 65 is H and the outputs of the voltage comparators 51, 52, 53 are also H, the set input circuit 64 outputs H to the set input of the corresponding RS flip-flop. RS flip-flops 61 and 6
In steps 2 and 63, the output of the corresponding set input is turned to H by turning to H, and thereafter the L output is maintained regardless of the set input. Therefore, when the battery voltage is equal to or higher than a predetermined rising rate at the time of discharging or standby, the storing operation to the RS flip-flop is stopped, and when the rising rate of the battery voltage is lower than a predetermined value, the output of the voltage comparator is output. The corresponding storage becomes possible. When the reset inputs of the RS flip-flops 61, 62 and 63 are turned to H by charging, these outputs become H and the storage is erased.

FIG. 2 is a charge / discharge characteristic diagram according to the first embodiment of the present invention. A battery in a fully charged state is subjected to constant current discharge up to a discharge end voltage with two pauses, and charging is performed in a standby state. The battery voltage and the remaining amount display level at the time of performing are shown. In FIG. 2, when the battery voltage is equal to or higher than a predetermined rising rate, such as when the discharge is stopped halfway, the storage operation to the RS flip-flop is stopped as described above, and the remaining amount display is performed based on the output of the RS flip-flop. Therefore, the problem of the section A in FIG. 6 does not occur,
Even when the discharge is restarted, the remaining amount display is performed based on the output of the RS flip-flop, so that the problem in the section B in FIG. 6 does not occur. The oscillating circuit 77 performs an oscillating operation when the RS flip-flop 61 outputs L or the charging detection circuit 31 outputs H. Therefore, during charging, the oscillation circuit 77 performs an oscillating operation,
Since the RS flip-flops 61, 62, and 63 output H as described above, three LEDs blink.

As described above, according to the first embodiment of the present invention, the current detecting means 2 for measuring the magnitude of the charging / discharging current;
A battery comprising state detecting means 3 for determining whether charging, discharging or standby, comparison voltage correcting means 4 for correcting the input voltage of the voltage comparator, and the voltage comparator for detecting a drop in battery voltage and its peripheral circuits. A voltage comparing means for storing a decrease in the battery voltage based on an output of the battery voltage comparing means, and stopping the storing operation when a rate of increase in the battery voltage accompanying a decrease in the discharge current is equal to or higher than a predetermined value. 6 and display means 7 for displaying the remaining battery level based on the output of the storage means 6 and the output of the charge detection circuit 31, thereby providing accurate remaining power which is not affected by the stop or start of discharge or the decrease or increase of discharge current. In addition to being able to display the amount, three LEDs can be displayed blinking even during charging, which is convenient for recognizing the state of charge.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a configuration diagram showing a second embodiment of the present invention. In FIG. 3, reference numeral 58 denotes a reference voltage source which receives an output of the charge detection circuit 31 as an input. Reference numeral 65 denotes a battery voltage rise detection circuit which receives an output of the charge detection circuit 31 as an input. Reference numeral 66 denotes a reset input circuit, which is a two-input AND circuit that receives the output of the charge detection circuit 31 and the outputs of the voltage comparators 51, 52, and 53 as inputs. An oscillation circuit 77 receives the output of the RS flip-flop 61 as an input. Other configurations are basically the same as those in FIG. 1, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

The operation of the battery remaining amount display device of the present invention configured as described above will be described below.

The operations at the time of discharging and at the time of standby are the same as those of the first embodiment, so that the detailed description thereof will be omitted, and the operation at the time of charging will be described.

The reference voltage source 58 receives the H output of the charge detection circuit 31, and raises the output voltage by a predetermined value. Thereby, the battery voltage at the time of output inversion of the voltage comparators 51, 52, 53 becomes higher than that at the time of discharging. Therefore, by appropriately setting the rising value of the output voltage of the reference voltage source 58, the voltage comparators 51, 52, 53 according to the rise of the battery voltage due to the progress of charging.
Will be inverted (L output). The battery voltage rise detection circuit 65 receives the H output of the charge detection circuit 31 and outputs L, and the set input circuit 64 to which this is input outputs L to the set input of the corresponding RS flip-flop. In the reset input circuit 66, the output of the charge detection circuit 31 is H,
When the output of each of the voltage comparators 51, 52, 53 is L, H is output to the reset input of the corresponding RS flip-flop. In the RS flip-flops 61, 62, and 63, the output is set to H by the corresponding reset input turning to H.
After that, the H output is maintained regardless of the reset input. FIG. 4 is a charge characteristic diagram according to the second embodiment of the present invention, showing the battery voltage and the remaining battery level when quick charge is performed from the discharge end state. In FIG. 4, the battery voltage increases as the charging progresses. As a result, the voltage comparator becomes 5
The output changes to L in the order of 1, 52, and 53, and the corresponding RS flip-flop also outputs H in the order of 61, 62, and 63. In response to this, the remaining amount display level is sequentially lit from blinking one to lighting three. After the quick charge is completed, the battery voltage decreases and the output of the voltage comparator 53 changes to H. However, the fact that the output of the voltage comparator has changed to L is stored in the RS flip-flop. Be kept constant.

As described above, according to the second embodiment of the present invention, the reference voltage source 58 to which the output of the charge detection circuit 31 is input and the output of the charge detection circuit 31 are added to the first embodiment of the present invention. Is provided, a reset voltage input circuit 66 receives the output of the charge detection circuit 31 and the output of the voltage comparator, and an oscillation circuit 77 receives the output of the RS flip-flop 61 as an input. As a result, the progress of charging can be easily recognized by the lighting state of the LED, and all three lamps are lit in the first embodiment even when charging is stopped halfway. However, in the second embodiment, It is very convenient to use because the display is in accordance with the progress of charging.

[0023]

As described above, according to the present invention, the current detecting means for measuring the magnitude of the charging / discharging current, the battery voltage comparing means for detecting the decrease in the battery voltage, and the state for judging whether to charge, discharge or stand by. Detection means, comparison voltage correction means for performing a correction for lowering the battery voltage drop detection value in accordance with an increase in the discharge current, and storage of the battery voltage drop based on the output of the battery voltage comparison means; Storage means for halting the storage operation when the voltage rises, and erasing the storage by turning the output of the state detection means to charge detection, and display means for displaying the remaining battery level based on the storage result of the storage means With this arrangement, it is possible to accurately display the remaining amount without being affected by the stop or start of the discharge or the decrease or increase of the discharge current, and also to perform a dedicated display at the time of charging, which is convenient for recognizing the state of charge.

At the time of charging, the detected value of the battery voltage drop of the battery voltage comparing means is increased, and the storage of the storage means is erased by inverting the output of the battery voltage comparing means, so that the charging can proceed. The display according to the state becomes possible, which is convenient for recognizing the charging process and using the battery after stopping charging.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a charge / discharge characteristic diagram in the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a charging characteristic diagram according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional example.

FIG. 6 is a charge / discharge characteristic diagram in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Secondary battery 2 Current detection means 3 State detection means 4 Comparison voltage correction means 5 Battery voltage comparison means 6 Storage means 7 Display means 8 Terminal

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-66251 (JP, A) JP-A-3-108679 (JP, A) JP-A-51-150636 (JP, A) JP-A-50- 160743 (JP, A) JP-A-1-100479 (JP, A) JP-A-61-89573 (JP, A) JP-A-3-108679 (JP, A) JP-A-64-59176 (JP, A) JP-A-54-135323 (JP, A) JP-A-63-115763 (JP, U) JP-A-63-75877 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/36

Claims (3)

(57) [Claims] A current detector for measuring a magnitude of a charging / discharging current; a battery voltage comparing means for detecting a decrease in the battery voltage by a voltage comparator which receives a divided voltage of the battery voltage and a reference voltage; State detecting means for determining whether the state of the battery is charging, discharging, or standby with the output of the current detecting means as an input; and comparing the voltage according to the output of the current detecting means when the output of the state detecting means is discharge detection. Increase or decrease the divided voltage or reference voltage of the battery voltage which is the input of the
A comparison voltage correction means for performing a correction for lowering the battery voltage drop detection value in accordance with an increase in the discharge current; and a memory for storing a drop in the battery voltage based on the output of the battery voltage comparison means, and when the battery voltage rises with a decrease in the discharge current. Has storage means for halting the storage operation and erasing the storage when the output of the state detection means changes to charge detection, and display means for displaying the remaining battery level based on the storage result of the storage means. Battery level indicator. 2. The battery remaining amount display device according to claim 1, further comprising storage means for stopping the storage operation when the rate of increase of the battery voltage accompanying the decrease of the discharge current is equal to or higher than a predetermined value. 3. The battery voltage comparing means for increasing the reference voltage by a predetermined value when the output of the state detecting means is in a charged state, and the battery voltage comparing means when the output of the state detecting means is in a charged state. 2. The battery remaining amount display device according to claim 1, further comprising storage means for erasing the storage of the battery voltage drop by inverting the output.