JP3191555B2 - Low battery detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery-operated device that can be used as either a dry battery or a rechargeable battery. The present invention relates to a battery detection device.

[0002]

2. Description of the Related Art In recent years, in a battery-operated device, a reduced-battery detection device is often used to detect a reduced-battery condition and notify a user shortly before the battery voltage decreases as the operation capability of the device stops. ing.

[0003] A conventional example of a reduced battery detection device will be described below with reference to the drawings. FIG. 4 is a circuit diagram of a conventional reduced battery detection device. In FIG. 4, a jack 1 for supplying an external power supply has a first terminal 1a, a second terminal 1b, and a third terminal 1c. The cathode of the diode 2 is connected to the (+) pole of the battery 12 and the power supply output line 17 which are connected in series. The second terminal 1b of the jack 1 is connected to the (-) pole of the battery 11 connected in series to the battery 12, and the third terminal 1b connected to GND when no external power plug is connected to the jack 1. Contact with the terminal 1c. A negative terminal of the battery 11 is connected to a charging terminal 16 serving as a third battery terminal having a structure such that it contacts only when the battery 11 is a rechargeable battery, and is connected to GND via a charging resistor R3. It is connected.

Further, a power supply output line 17 is connected to an output terminal 18 and to GND via a series circuit of resistors R8 and R9, and a comparator having an output terminal 19a is provided at a connection point between the resistors R8 and R9. 4, the (+) terminal of the comparator 4 is connected to the (−) terminal of the reference power supply 3, and the (−) terminal of the reference power supply 3 is connected to GND.

The operation is described below. First, when an external power plug (not shown) is removed from the jack 1, the terminal 1 of the jack 1 is disconnected.
Since b and 1c are in contact with each other, power is supplied from the batteries 11 and 12 to a device (not shown) via the power supply output line 17 and the output terminal 18. When an external power plug is inserted into the jack 1, the terminals 1 b and 1 c of the jack 1 do not come into contact with each other in response to the connection operation. Cannot be operated. Power is supplied to the device from an external power supply through the diode 2, the power output line 17, and the output terminal 18. Power supply voltage is resistor R
8 is divided by R9, compared by the reference power supply 3 and the comparator 4, and a value of (+) is outputted to the terminal 19a when the voltage is equal to or higher than the threshold voltage, and a value (-) is outputted below the threshold voltage. Although not shown, the output of the comparator 4 is input to a microcomputer, and the result is displayed on a display.

FIG. 2 is a block diagram showing the relationship between the battery terminals and the batteries. The (+) terminal 13 which is the first battery terminal connected to the (+) pole 12a of the battery 12, and the (-) terminal of the battery 11 ) (−) Terminal 14 which is a second battery terminal connected to pole 11 e
And the (−) pole 12e of the battery 12 and the (+) pole 1 of the battery 11
It has a common terminal 15 for connecting 1a and a charging terminal 16 as a third battery terminal. The rechargeable battery 11 is
It comprises a (+) pole 11a, a (-) pole 11b, a tube 11c made of an insulating material, and a charging electrode 11d not covered with a tube on the side, and the charging terminal 16 is in contact with the charging electrode 11d. . Here, when the battery is a dry battery, the entire side surface is covered with a tube, and the charging electrode 1
1d does not exist.

In FIG. 4, the charging terminal 16 is connected to GND by a resistor R3 for determining a charging current. Therefore, when an external power plug is connected to the jack 1 and a rechargeable battery is mounted, The charging current flows through the charging terminal 16 and the resistor R3, and the battery is charged. When a dry battery is inserted, the charging terminal 16 is not connected to the dry battery and is not charged.

Here, the discharge characteristics of the rechargeable battery and the dry battery will be compared with reference to FIG. In FIG. 3, the discharge characteristic of the rechargeable battery is (a), and the discharge characteristic of the dry battery is (b). Dry batteries have a relatively high initial voltage, but gradually decrease in voltage with time, and rechargeable batteries have a low initial voltage but a relatively flat voltage change, and finally have a characteristic of sharply decreasing. Assuming that the device can operate up to the voltage shown in FIG. 5E, (d), which is slightly above this value, is set as the threshold of the reduced battery detection device. It becomes impossible to use the battery, and there is no point in providing a reduced battery detection device. If the threshold value is set to the level shown in FIG. It can be used for a long time.

[0009]

As described above, in the above-described conventional reduced battery detection device, when a rechargeable battery is used, the reduced battery is detected shortly before the device stops operating. When the threshold voltage is set, the detection voltage is the same when dry batteries are used, even though the discharge characteristics of the batteries are different. I was

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a reduced-battery detecting device which detects whether a rechargeable battery or a dry battery is used just before the device stops operating. And

[0011]

In order to achieve the above object, a reduced battery detection device according to the present invention is responsive to an external power supply input terminal for supplying external power and a connection operation of the external power supply to the external power supply input terminal. And a first switch element for disconnecting the battery circuit in response to the external power supply voltage to the external power supply input terminal, and the first terminal and the second terminal.
In the case of batteries covered with rim material, there is no connection,
A battery terminal having a third terminal for charging connected only to the charging terminal of the rechargeable battery formed without the side clothing ;
Charging circuit for charging the rechargeable battery and rechargeable battery inserted
When the external power supply is connected in a state of being, first switch
Despite the fact that GND is cut by the
A second switch element that operates by connecting the third terminal to a charging circuit; and a battery type that detects the rechargeable battery by connecting the third terminal when the rechargeable battery is inserted. , And a comparator for comparing the output voltage of the threshold switching circuit with a reference voltage.

[0012]

According to the present invention, in the above configuration, the first switch element is connected to an external power supply terminal in response to an operation of connecting the external power supply to the external power supply terminal or in response to an external power supply voltage applied to the external power supply terminal. And the second switch element operates the charging circuit via the third terminal for charging to charge the rechargeable battery when the external power supply voltage is connected. When the external power is not supplied to the external power input terminal, the device is operated by the battery with the first switch element, and the type of the battery, that is, the rechargeable battery is determined based on the voltage of the third terminal for charging by the threshold switching circuit. Detecting whether the battery is a primary battery, switching the threshold value according to the battery type, and comparing the output voltage of the threshold value switching circuit with a reference voltage by a comparator to determine whether the battery can be used. Different.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a reduced battery detection device according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a circuit diagram of a low battery detection apparatus according to one embodiment of the present invention. 1, components having the same functions as those in FIG. 4 of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted. The first terminal 1a of the jack 1 is connected to the resistors R1 and R2, the other end of the resistor R1 is connected to GND, and the other end of the resistor R2 is connected to the base of the transistor Q1. A charging terminal 16 as a third battery terminal is connected to a resistor R3.
The other end of the resistor R3 connected to the transistor R4 and determining the charging current is connected to the collector of the transistor Q1, and the other end of the resistor R4 is connected to the base of the transistor Q2. The emitter of the transistor Q1 is connected to GND.

A resistor R5 is connected between the base and the emitter of the transistor Q2 having a polarity opposite to that of the transistor Q1,
This emitter is connected to a power output line 17 extending from the cathode of the diode 2 to the output terminal 18 via the (+) pole of the battery 12. The collector of the transistor Q2 is a resistor R
6, R7 connected to GND and resistors R6, R7
Is connected to a transistor Q having the same polarity as the transistor Q1.
3 and its emitter is connected to GND.

The power supply output line 17 further includes a resistor R8,
A series circuit of 89 and R10 is connected to GND, and a connection point of the dividing resistors R8 and R9 is connected to the (+) of the comparator 4.
The terminal of the dividing resistor R9 and R10 is connected to the collector of the transistor Q3, and the (-) terminal of the comparator 4 is connected to the (+) pole of the reference power supply 3 whose (-) pole is connected to GND. It is connected. The configuration diagram of the battery terminal in FIG. 2 is the same as that described in the conventional example. Here, the case where two batteries are used has been described. However, when there are many batteries, the number of common terminals may be increased, and when only one battery is used, the common terminals are unnecessary.

The operation of the battery reduction detecting device according to one embodiment of the present invention configured as described above will be described below.
FIG. 3 is a graph of the discharge characteristics of the battery described above.
(B) is a discharge characteristic curve when a dry battery is used. When two batteries are used, if the battery is to be detected shortly before the device does not operate normally, the threshold voltage becomes the level (c) (about 2.3) in the case of a rechargeable battery.
V), and in the case of a dry battery, the level (d) (about 1.9 V) is desirable.

In FIG. 1, when a plug (not shown) for supplying external power is removed from the jack 1, power is supplied to the device from the batteries 11 and 12 via the power output line 17 and the power output terminal 18. Since the terminals 1b and 1c of the jack 1, which is the first switch element for determining whether to operate with a battery or an external power supply, are in contact with the battery, the (-) pole of the battery 11 falls to GND, Even if a rechargeable battery is connected, the charging terminal 16 drops to GND, and the charging circuit becomes irrelevant.

When an external power supply plug is inserted and a voltage is supplied from an external power supply from the external power supply input terminal 1a, the terminals 1b and 1b of the jack 1 respond to the connection operation.
c, the batteries 11 and 12 have their (−) sides disconnected from GND, and a power supply voltage is supplied from an external power supply to a device (not shown) through the terminal 1 a of the jack 1, the diode 2, the power supply output line 17 and the output terminal 18. Supplied.
Then, at the same time, the transistor Q1 is turned on from the external power supply via the resistor R2, and in the case of a rechargeable battery, the battery is charged through the charging terminal 16, the resistor R3 which determines the charging current, and the transistor Q1. A primary battery such as a dry battery is not charged because the charging terminal 16 is not connected to the battery.

That is, the transistor Q1, the resistor R1
And a second switch circuit comprising R2 enables the operation of a charging circuit R3 for charging a rechargeable battery in response to an incoming external power supply.

When the external power supply is not connected, the voltage is blocked by the diode 2 and the voltage of the batteries 11 and 12 is not applied to the base of the transistor Q1, so that the transistor Q1 is turned off and the resistor R3 which determines the charging current is disconnected. Here, the resistor R1 is provided for surely turning off the transistor Q1 via the resistor R2 when an external power supply is not connected.

When the external power supply is not connected and the battery 11 is a rechargeable battery, the charging terminal 16 is connected to the (-)
, The battery voltage is applied between the emitter of the transistor Q2 and the resistor R4,
The base current flows through the resistor R4 and the transistor Q
2 is turned on, and the transistor Q is passed through the resistor R6.
3 is turned on, the power supply voltage of the power supply output line 17 is divided by the dividing resistors R8 and R9 and compared by the reference power supply 3 and the comparator 4, and when the power supply output line 17 is about 2.3 V or more (+), Hereinafter, the value (−) is output from the comparison output terminal 19. Further, when the battery 11 is a dry battery, the charging terminal 16 is not connected to the battery terminal, so that no voltage is applied to the base of the transistor Q2, and the transistor R2 is connected by the resistor R5.
Of the transistor Q
2 is turned off, and the transistor Q is turned on by the resistor R7.
3 has the same potential between the emitter and the base, and the transistor Q3 is turned off. Therefore, the power supply voltage is divided by the dividing resistor R8 and the dividing resistor (R9 + R10) and compared with the reference power supply 3 and the comparator 4, and (+) Is output to the comparison output terminal 19 at 1.9 V or more, and (-) is output at the comparison output terminal 19 below.

For example, assuming that the reference voltage is 1 V, in this example, the threshold voltage of the rechargeable battery is 2.3 V, and the resistance division ratio may be 1 / 2.3.
It can be seen that it should be 1.9.

That is, the transistors Q2 and Q3 and the resistors R4, R5, R6, R7, R8, R9 and R10 detect the type of the battery from the voltage of the third terminal for charging and determine the threshold according to the type of the battery. A threshold switching circuit for switching the value is formed, and the comparator 4 and the reference voltage 3 form a comparison circuit for comparing the output voltage determined by the threshold switching circuit with the reference voltage.

The output of the output terminal 19 of the comparator 4 is not shown, but is input to a microcomputer for controlling the entire apparatus, and when the output of the comparator 4 has a value of (-), for example, If the characters stored in the ROM or the like in advance, for example, "battery replacement", "BATTERY", or a figure with a cross marked on the battery figure are programmed to be displayed on the display, and displayed on the liquid crystal display, etc. Good.

It is to be noted that the output of the comparator 4 may be displayed as it is or without amplification via an LED without using a microcomputer. In this embodiment, the case where two batteries are used in series has been described. However, the same applies to the case where one battery or many batteries are connected in series. In this case, the reference voltage or the dividing ratio of the resistor may be changed. It is.

The case where the jack 1 has the first switch element which switches in response to the insertion of the plug therein has been described. This switch element detects, for example, a voltage between the terminal 1a and the diode 2 and detects the voltage. At the time of HIGH, a transistor switch for determining whether to drop the (−) pole of the battery 11 to GND may be provided.

Although the second switch element is a transistor in the embodiment, it may be a switch having a mechanical contact responding to the connection of an external power supply like the first switch element. Such modifications are optional in the present invention.

In this embodiment, the (-) pole of the battery is configured so as to partially remove the insulating coating for detecting the rechargeable battery. However, the position excluding the insulating coating is not limited to the illustrated structure. Also, instead of the (-) pole, the (+) pole may be used, in which case it can be easily realized by changing the circuit connection of the reduced battery detector.

Further, the circuit connection states and voltage values in the above embodiment are merely examples, and may be changed within the scope of the present invention.

[0031]

As described above, the reduced battery detection device according to the present invention has an external power input terminal for supplying external power and an external power supply connected to the external power input terminal, or has an external power supply connected thereto. a first switching element to disconnect the battery circuit in response to an external power supply voltage to the power input terminal, a first end
The entire side, together with the child and the second terminal, was covered with insulating material.
If the batteries are not connected, remove the
A battery terminal having a third terminal for charging that is connected only to the charging terminal of the formed rechargeable battery; a charging circuit for charging the rechargeable battery; > When the unit power supply is connected , G
The third terminal even though the ND is disconnected;
A second switch element which operatively connected to the charging circuit, said third terminal contact when the rechargeable battery is inserted
A comparator for comparing a threshold value switching circuit for switching the <br/> threshold value of battery is detected the charging batteries by being continued, the output voltage and a reference voltage of said threshold switching circuit And a configuration having:

Therefore, when external power is applied from the external power input terminal, the battery circuit can be cut off by the first switch element and the rechargeable battery can be charged using the third terminal for charging and the charging circuit. when not apply a power to the external power supply input terminal can Rukoto operate the equipment battery in the inoperative a charging circuit in the second switching element. The third type from the voltage of the battery terminals for charging the threshold value switching circuits, that is, detecting whether the rechargeable battery or dry battery, a voltage corresponding to a threshold value corresponding to the type of cell output can, since the determination of the output voltage and the reference voltage and the battery availability compared in a comparator with the threshold switching circuits depending on their discharge characteristics in dry battery in a rechargeable battery, the operation of the device is stopped Shortly before the detection and output of the low battery
it can. Therefore, by displaying predetermined figures and characters via an LED or the like or a microcomputer, it is easy to use and the battery life can be maximized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a reduced battery detection device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing the relationship between a battery terminal and a battery common to the present invention and a conventional example.

FIG. 3 is a discharge characteristic diagram of the same battery.

FIG. 4 is a circuit diagram of a conventional example of a reduced battery detection device.

[Explanation of symbols]

 Q1, Q2 Transistors R1 to R7 Resistors R8 to R10 Split resistors 1 Jack 1a External power input terminals 1b, 1c Terminals (first switch elements) 2 Diode 3 Reference power supply 4 Comparator 11 Battery 11d Charging electrode 12 Battery 13 ( +) Terminal 14 (-) terminal 16 Charging terminal (third terminal) 18 Output terminal 19 Comparison output terminal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 31/36

Claims (4)

(57) [Claims] An external power input terminal for supplying an external power; a first switch element for disconnecting a battery circuit in response to an operation of connecting the external power to the external power input terminal; and a first terminal. And the second side together with the second terminal with insulating material
If the battery is covered, it will not be connected.
A battery terminal having a third terminal for charging connected only to the charging terminal of the rechargeable battery formed without the clothing, a charging circuit for charging the rechargeable battery, and an external device with the rechargeable battery inserted when the power supply is connected
, GND is disconnected by the first switch element
Despite of this, the third terminal is connected to the charging circuit when the third terminal is connected to the charging circuit , and the third terminal is connected when the rechargeable battery is inserted.
And a threshold value switching circuit for switching the threshold of the battery by detecting the charge batteries by being, reduced battery detection and a comparator for comparing the output voltage with a reference voltage of said threshold switching circuit apparatus. 2. An external power supply input terminal for supplying external power, a first switch element for disconnecting a battery circuit in response to a voltage of the external power supply to the external power input terminal, a first terminal, Along with the second terminal, the whole side surface is made of insulating material
If the battery is covered, it will not be connected.
A battery terminal having a third terminal for charging connected only to the charging terminal of the rechargeable battery formed without the clothing, a charging circuit for charging the rechargeable battery, and an external device with the rechargeable battery inserted when the power supply is connected
, GND is disconnected by the first switch element
Despite of this, the third terminal is connected to the charging circuit when the third terminal is connected to the charging circuit , and the third terminal is connected when the rechargeable battery is inserted.
And a threshold value switching circuit for switching the threshold of the battery by detecting the charge batteries by being, reduced battery detection and a comparator for comparing the output voltage with a reference voltage of said threshold switching circuit apparatus. 3. The first switch element disconnects a connection from a battery terminal having the same potential as the third terminal.
Or the reduced battery detection device according to 2. 4. The battery reduction detection according to claim 1, wherein the output of the detection circuit indicates the necessity of battery replacement by visible light, graphics, characters, or the like directly or through a microcomputer. apparatus.