JPH09203752A - Voltage reduction display circuit of electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display circuit of electronic equipment using as power supply both a chargeable battery and a nonchargeable battery, in which it is possible to precisely perform the displaying operations of voltage reduction in compliance with the sort of battery in use. SOLUTION: A comparator circuit 16 has two input terminals, one of which is fed with a reference voltage while the other terminal fed with a voltage obtained by dividing a battery voltage and performs inversion of the level of the output signal when the battery voltage has sunk to the specified level. Besides this comparator circuit 16, the voltage reduction display circuit according to the invention includes a display 11 to display drop of the battery voltage when the level of the output signal from the comparator circuit 16 is inverted by the drop of the battery voltage, wherein such an arrangement is introduced that the detecting level of the battery voltage differs between a chargeable battery and nonchargeable battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device using a rechargeable battery and a non-rechargeable battery as a power source, and more particularly to a reduced voltage display circuit for displaying a decrease in battery voltage.

[0002]

2. Description of the Related Art Portable electronic devices such as disk players are configured to use a battery as a power source. A battery used in such an electronic device is a nickel-cadmium battery. There are rechargeable batteries that can be recharged and non-rechargeable batteries that cannot be recharged, such as alkaline batteries. Such electronic devices are
The main body is provided with a battery accommodating portion for accommodating a rechargeable battery or a non-rechargeable battery, and is also provided with a power supply jack to which a power source for charging the rechargeable battery is input.

In an electronic device configured to operate by a power source obtained from a battery, the voltage of the battery is a predetermined value,
That is, it is provided with a display means for informing the user that it is necessary to replace the battery or perform a charging operation when the voltage value is called a reduced voltage.

[0004]

A reduced voltage display circuit of an electronic device is configured to detect a voltage drop of a battery, and when the voltage value drops to a predetermined value, the detection circuit works to display on a display. ing. The change in the battery voltage with respect to the use time of the rechargeable battery and the non-rechargeable battery is shown in the characteristic diagram shown in FIG. 2, in which the line A represents the characteristic of the rechargeable battery and the line B represents the characteristic. Indicates the characteristics of the non-rechargeable battery.

As is clear from the characteristic diagram, the characteristics of the rechargeable battery and the non-rechargeable battery are greatly different, and therefore the detection level of the reduced voltage is the same when the rechargeable battery and the non-rechargeable battery are used. Then, there is a problem that it is not possible to accurately display the battery replacement time or the charging time.

The present invention intends to provide a reduced voltage display circuit which solves such a problem.

[0007]

In the reduced voltage display circuit of the present invention, a reference voltage is input to one input terminal, a voltage obtained by dividing the battery voltage is input to the other input terminal, and the battery voltage is It is configured by a comparison circuit in which the level of the output signal is inverted when the level of the output signal is lowered to a predetermined voltage value, and a display which displays the drop of the battery voltage when the level of the output signal of the comparison circuit is inverted by the drop of the battery voltage Has been done.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit shown in FIG. 1 shows one embodiment of the reduced voltage display circuit of the present invention, in which 1 is provided in an AC adapter which is a commercial power source and converts an AC signal into a DC signal. A power jack into which a power plug is inserted, a positive side terminal 2, a ground terminal 3, and a switching contact 4 which is disconnected from the ground terminal 3 when the power plug is inserted.
It is composed of

A power switch 5 is a first terminal 5a connected to the positive terminal 2 of the power jack 1 through a diode 6 for preventing backflow and D for boosting a DC voltage.
It has a second terminal 5b connected to the C-DC converter 7. Reference numeral 8 denotes a battery accommodated in a battery accommodating portion formed in the main body of a disc player which is an electronic device, the positive terminal of which is the first terminal 5a of the power switch 5.
And the negative terminal is connected to the switching contact piece 4 of the power jack 1.

Reference numeral 9 denotes a disk drive device in which a spindle motor for rotationally driving the disk, a drive mechanism for an optical pickup for reading signals recorded on the disk, and the like are incorporated. 10 is incorporated in the disk drive device 9. The control circuit 11 controls the operation of the spindle motor and the like, and 11 is an indicator whose operation is controlled by the control circuit 10. The display circuit 11 performs the display operation of the time information and the like obtained from the disk and reduces the battery voltage. It has a built-in function to display that it has decreased.

Reference numeral 12 is a reference voltage generating circuit for outputting a reference voltage to the output terminal when the power switch 5 is in the ON state.
Reference numeral 3 is a voltage dividing circuit for dividing the power supply voltage input via the switch 5, and is composed of a first resistor 14 and a second resistor 15. The output terminal 16 is the control circuit 1
0 is a comparison circuit connected to the detection signal input terminal 10a provided at 0, and is divided by the first input terminal 17 and the voltage dividing circuit 13 to which the reference voltage output from the reference voltage generation circuit 12 is input. The second input terminal 18 to which the voltage obtained from the pressure point A is input is provided.

Reference numeral 19 denotes a switch which is closed when the rechargeable battery is stored in the battery storage portion, and has a first terminal 19a and a grounded second terminal 19b. Reference numeral 20 is a detection level switching transistor whose collector is connected to the voltage dividing point A of the voltage dividing circuit 13 through a detection level switching resistor 21 and whose emitter is grounded. Reference numeral 22 is the detection level switching transistor 2
0 is a detection level switching control transistor whose collector is connected to its base through a resistor 23 and whose emitter is connected to the second terminal 5b of the power switch 5 in order to control the operation of 0. Resistance 2
4 is connected to the first terminal 19a of the switch 19.

Reference numeral 25 denotes a charging transistor whose collector is connected to the negative terminal of the battery 8 through the charging resistor 26 and whose emitter is grounded. Reference numeral 27 denotes a collector for controlling the operation of the charging transistor 25. A charge control transistor connected to its base via a resistor 28 and having its emitter connected to the positive terminal 2 of the power jack 1, the base of which is the first of the switch 19 via a resistor 29. It is connected to the terminal 19a.

The present invention is configured as described above. Next, the operation will be described. First, the case where a non-rechargeable battery is used as the battery 8 will be described. When a non-rechargeable battery is used as the battery 8, the switch 19 is open.

When the power switch 5 is turned on with the non-rechargeable battery housed in the battery housing part, the DC voltage obtained from the battery 8 passes through the power switch 5 and becomes DC-
The DC voltage which is applied to the DC converter 7 and boosted is output to the output terminal of the DC-DC converter 7. When a DC voltage is output to the output terminal 7 of the DC-DC converter 7, the DC voltage is supplied to the disk drive device 9 and the control circuit 10 as operating power.

When an operation such as reproduction is performed in such a state, the control operation of the control circuit 10 for the disk drive device 9 is performed, and the reading operation of the signal such as music recorded on the disk and the demodulating operation of the signal are performed. Done. Therefore, the signal demodulated by the above-described operation is amplified by the amplifier circuit (not shown) and then emitted by the speaker, so that the reproduction / listening operation of the signal recorded on the disk can be performed.

When a non-rechargeable battery is used as an operating power source, the detection level switching control transistor 22 is in a non-conducting state because the switch 19 is in an open state, and the detection level switching control transistor 22 is operated by the detection level switching control transistor 22. The detection level switching transistor 20 connected so that its operation is controlled is non-conductive. Therefore, in such a state, the power supply voltage, which is the output voltage of the battery 8, is divided by the first resistor 14 and the second resistor 15 forming the voltage dividing circuit 13 and input to the second input terminal 18 of the comparison circuit 16. Therefore, the voltage and the reference voltage generating circuit 12
The output reference voltage will be compared.

When the capacity of the battery 8 is sufficient, since the battery voltage is high, the L (low) level signal is output to the output terminal of the comparison circuit 16. as a result,
The control operation of the control circuit 10 causes the display 11 to display that the battery voltage is sufficiently high.

When the reproducing operation of the disc player is performed, the battery 8 is exhausted, and the output voltage decreases as the capacity of the battery 8 is exhausted. The voltage V2 (Fig. 2) in which the voltage of the battery 8 is set as the reduced voltage of the non-rechargeable battery
When the level of the output signal of the comparison circuit 16 decreases to L
Inverts to H (higher) than the level. When such an H level signal is input to the detection signal input terminal 10a provided in the control circuit 10, the control operation of the control circuit 10 indicates that the voltage of the battery 8 has dropped to a reduced voltage. 11 is displayed. Therefore, the user can recognize that the battery 8 needs to be replaced.

As described above, the display operation of the voltage drop of the battery 8 is performed, but in such a state, the charging control transistor 27 is not supplied with power to the emitter and the switch 19 is opened. Therefore, the charging transistor 25 is in the non-conducting state, and the charging transistor 25 connected so that the operation is controlled by the charging controlling transistor 27 is in the non-conducting state. In such a state,
When the power plug of the AC adapter is inserted into the power jack 1, the switching contact piece 4 is disconnected from the ground terminal 3 and a DC voltage is supplied to the positive terminal 2.

When the power plug of the AC adapter is inserted into the power jack 1, the charging control transistor 2
Power is supplied to the emitter of No. 7, but since the switch 19 is open, it is not biased, and the charge control transistor 27 is non-conductive. Therefore,
The charging transistor 25, the operation of which is controlled by the charging control transistor 27, is in a non-conductive state, and the negative terminal of the battery 8 is in a non-grounded state. Therefore, the DC voltage supplied from the AC adapter is not applied to the battery 8 and no problem occurs. In such a state, when the power switch 5 is turned on, the DC voltage supplied from the AC adapter is supplied to the DC-DC converter 7, so that the above-mentioned boosted DC power output from the DC-DC converter 7 is used. The playback operation of the disc player can be performed.

The operation when the non-rechargeable battery is used as the battery 8 is performed as described above. Next, the operation when the rechargeable battery is used will be described. When the rechargeable battery is stored in the battery storage portion instead of the non-rechargeable battery, the switch 19 which has been in the open state is closed.

When the power switch 5 is turned on with the rechargeable battery housed in the battery housing, the DC voltage obtained from the battery 8 is passed through the power switch 5 to DC-D.
The DC-DC converter 7 is applied to the C converter 7.
The DC voltage boosted by is output. DC-
Since the DC voltage boosted by the DC converter 7 is supplied to the disk drive device 9 and the control circuit 10, the reproduction operation of the disk player can be performed as in the case of using the non-rechargeable battery.

When a rechargeable battery is used as the operating power source, the switch 19 is in the closed state, so that the detection level switching control transistor 22 is biased into the conductive state. The detection level switching control transistor 2
When 2 becomes conductive, a base current is supplied to the base of the detection level switching transistor 20 through the emitter / collector path thereof, so that the detection level switching transistor 20 is biased and becomes conductive. Therefore, in such a state, the power supply voltage which is the output voltage of the battery 8 constitutes the voltage dividing circuit 13, and the first resistor 14 and the second resistor 1
5, and the voltage is divided by the detection level switching resistor 21 and input to the second input terminal 18 of the comparison circuit 16, and this voltage is compared with the reference voltage output from the reference voltage generation circuit 12. Will be. In such a case, since the detection level switching resistor 21 is connected in parallel to the second resistor 15, it is detected by comparing with the voltage V2 detected in the case of the non-rechargeable battery described above. The voltage value V1 is set to a high detection level.

When the charge capacity of the battery 8 is sufficient, the battery voltage is high, so that the output terminal of the comparison circuit 16 is L
The level signal is output. As a result, the control operation of the control circuit 10 causes the display 11 to display that the battery voltage is sufficiently high. The output voltage decreases as the battery 8 is exhausted, but that voltage is the voltage V1 set as the voltage reduction of the rechargeable battery.
When it reaches (FIG. 2), the level of the output signal of the comparison circuit 16 is inverted from the L level to the H level. When such an H level signal is input to the detection signal input terminal 10a provided in the control circuit 10, the control operation of the control circuit 10 indicates that the voltage of the battery 8 has dropped to a reduced voltage. 11 is displayed. Therefore, the user can recognize that the capacity of the rechargeable battery used as the battery 8 is reduced and that the battery 8 needs to be charged.

As described above, the display operation of the voltage drop of the battery 8 is performed, but in such a state, the power supply is not supplied to the emitter of the charge control transistor 27, so that the switch 19 is closed. Even in this state, the charging transistor 25 is in a non-conducting state, and the charging transistor 25 connected so that the operation is controlled by the charging controlling transistor 27 is in a non-conducting state. In such a state, A
When the power plug of the C adapter is inserted into the power jack 1, the switching contact piece 4 is separated from the ground terminal 3 and a DC voltage is supplied to the positive terminal 2.

When the power plug of the AC adapter is inserted into the power jack 1, the charging control transistor 2
Since power is supplied to the emitter of No. 7, the charge control transistor 27 is biased and becomes conductive. When the charge control transistor 27 becomes conductive,
Since a bias current is supplied to the base of the charging transistor 25 through the emitter / collector path, the charging transistor 25 becomes conductive. When the charging transistor 25 becomes conductive, a charging current flows through the diode 6, the charging resistor 26 and the collector-emitter path of the charging transistor 25.
The battery 8 can be charged.

In the present embodiment, the switch 19 is configured to be closed when the rechargeable battery is stored in the storage portion, but the switch is closed when the non-rechargeable battery is stored. It can also be configured. Further, the switching operation of the reduced voltage detection level is configured to be performed by switching the voltage division ratio of the power supply voltage input to the second input terminal 18 of the comparison circuit 16. However, the reference voltage input to the first input terminal 17 is used. It can also be configured to be performed by switching.

[0029]

According to the reduced voltage display circuit of the present invention, when the battery voltage is reduced to the reduced voltage value, not only is it displayed that the voltage is decreasing, but also the displayed reduced voltage value is displayed. Since the rechargeable battery and the non-rechargeable battery are made different from each other, the detection display operation corresponding to the characteristics of each battery can be performed.

Further, the present invention is provided with a switch that can be switched when a rechargeable battery or a non-rechargeable battery is housed in the battery housing part, and the detection voltage level is switched by opening / closing the switch. As a result, the battery type determination operation can be performed accurately and the configuration is simplified.

Further, according to the present invention, since the switch for controlling the charging operation of the rechargeable battery is used as the switch for switching the detection voltage level, the structure is simplified and the manufacturing cost is prevented from increasing. You can

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a reduced voltage display circuit of the present invention.

FIG. 2 is a characteristic diagram for explaining the operation of the present invention.

[Explanation of symbols]

 1 Power Jack 5 Power Switch 8 Battery 10 Control Circuit 11 Display 12 Reference Voltage Generation Circuit 13 Voltage Dividing Circuit 16 Comparison Circuit 19 Switch 20 Detection Level Switching Transistor 22 Detection Level Switching Control Transistor 25 Charging Transistor 27 Charging Control Transistor

Claims (5)

[Claims] 1. In an electronic device provided with a battery housing for housing a rechargeable battery or a non-rechargeable battery, a reference voltage is input to one input terminal and the battery voltage is distributed to the other input terminal. A comparator circuit in which the output voltage level is inverted when the compressed voltage is input and the battery voltage drops to a predetermined voltage value, and the battery voltage when the output signal level of the comparison circuit is inverted due to the battery voltage drop Of the battery voltage input to the input terminal of the comparison circuit when the rechargeable battery and the non-rechargeable battery are used. Voltage display circuit. 2. A switch that is switched when a rechargeable battery or a non-rechargeable battery is stored in the battery storage portion is provided, and the voltage division ratio of the battery voltage input to the input terminal of the comparison circuit is changed by switching the switch. The reduced voltage display circuit according to claim 1, wherein the reduced voltage display circuit is configured as described above. 3. In an electronic device provided with a battery housing for housing a rechargeable battery or a non-rechargeable battery, a reference voltage is input to one input terminal and a battery voltage is input to the other input terminal. And a comparison circuit in which the output signal level is inverted when the battery voltage drops to a predetermined voltage value, and a drop in the battery voltage is displayed when the output signal level of the comparison circuit is inverted due to the battery voltage drop A reduced voltage display circuit for an electronic device, comprising a display, wherein a reference voltage value input to an input terminal of a comparison circuit is different between when a rechargeable battery and a non-rechargeable battery are used. 4. A switch that is switched when a rechargeable battery or a non-rechargeable battery is housed in a battery housing is provided, and the value of the reference voltage input to the input terminal of the comparison circuit is changed by switching the switch. 4. The reduced voltage display circuit according to claim 3, wherein the reduced voltage display circuit is configured as described above. 5. A switch is provided which is switched when a rechargeable battery or a non-rechargeable battery is housed in a battery housing part, and the charging operation of the rechargeable battery is controlled by switching the switch. The reduced voltage display circuit according to claim 1 or claim 3.