JPH023814A - Battery back-up device - Google Patents

Abstract

PURPOSE:To obtain a sufficient time until the exchange of a main battery and to prevent the storage content of a memory circuit by connecting the main battery and an auxiliary battery different in a discharge characteristic to the main battery in parallel. CONSTITUTION:The main battery 9 holding the content of the memory circuit 6, a voltage inspection circuit 7 checking the voltage and the auxiliary battery 9A inspection circuit 7 checking the voltage and the auxiliary battery 9A which has the discharge characteristic different from that of the main battery 9, which is connected to the main battery 9 in parallel and which supplies power to the memory circuit 6 are provided. The voltage reduction of the main battery 9 is backed up based on the inspection result of the voltage detection circuits 7 and 7A, and the circuit is supported by the auxiliary battery 9A while the battery is exchanged.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a battery backup device that retains the contents of a memory circuit using a battery, and in particular can notify in advance of battery replacement when the battery voltage decreases. The present invention relates to a battery backup device.

[Conventional technology]

A conventional battery backup device of this type is shown in Fig. 346. This Figure 6 shows a block diagram of a conventional battery backup device, (1)
(2) is an AC power supply that supplies power to the memory circuit (6) to retain the contents during normal operation, and (2) is an AC/D that converts the AC current output from the AC power supply (1) into DC current.
C converter, (3B) and (3G) are diodes to prevent current backflow, (4) is resistor 1, (4^) is resistor 2, (5) is the power supply when AC power supply (1) is off. When converting the supply to the main battery (9), the memory circuit (6)
(6) is a memory circuit made of a volatile semiconductor memory element, and (9) is a capacitor that can hold the contents of the memory for a certain period of time. The main battery (7) to be supplied has a voltage reduction check circuit (7^) that checks whether the remaining life of the main battery (9) has become less than a predetermined voltage vA.
(8) is a voltage holding limit check circuit that checks whether the voltage of the main battery (9) has fallen below the holding voltage of the contents of the memory circuit (6), and (8) is the default remaining life of the main battery (9). The LED for voltage reduction indication indicates that the voltage has fallen below vA, and (8^) is a retention limit indicator that indicates that the voltage of the main battery (9) has fallen below the voltage that retains the contents of the memory circuit (6). This is an LED for use.

FIG. 7 shows a discharge characteristic diagram of a battery, in which time is plotted on the horizontal axis and voltage is plotted on the vertical axis, representing the transition of the voltage supplied from the battery.

The voltage maintains a constant voltage vc until Tc time, and after Tc time, the voltage gradually decreases, and the voltage after TA time is vA.
This indicates that the remaining life of the main battery (9) is 16 hours, and the voltage after Th time becomes Vh, and the memory contents cannot be held thereafter.

Next, the operation will be explained. To retain the contents of the memory circuit (6), either turn on the AC power source (1) to supply power, or use battery backup from the main battery (9).

When holding the main battery (9), as shown in Figure 6, the main battery (9) is checked by the voltage reduction check circuit (7) and it is determined that the remaining life is less than the predetermined voltage vA. In this case, the LED for voltage reduction indication (
8) to notify that the memory circuit (6) will soon be unable to hold its contents. Main battery (9)
is checked by the holding limit voltage check circuit (7A), and when it is determined that the voltage of the main battery (9) is less than the holding voltage of the content of the main battery (6), the holding limit display L
LED for voltage reduction indication that turns on E D (8^) to indicate that the contents of memory circuit (6) cannot be retained.
If both (8) and the retention limit display LED (8^) are not lit, this indicates that the contents of the memory circuit (6) will be retained for a long time.

If only this voltage reduction display LED (8) is lit, the contents of the memory circuit (6) are retained, but
If the life of the main battery (9) is low and both the voltage reduction display LED (8) and the retention limit display LED (8A) are lit,
If you carelessly turn off the AC power (1), the memory circuit (6)
indicates that the contents of the power supply will be destroyed and the power supply must be replaced immediately. Also, due to the discharge characteristics of the battery,
The time from when the voltage decrease display LED (8) lights up until the retention limit display LED (8A) lights up is short, and the voltage decrease display LED (8) and retention limit display LED (8A) are always lit. It is necessary to monitor D (8^).

Next, FIG. 8 is a configuration circuit diagram showing an example of the configuration of another conventional battery backup device. In the figure, (7
) is a voltage reduction check circuit (71A) composed of a battery voltage detection comparator.

(71B), (71C), and (710) are voltage dividing resistors for setting the comparator input voltage, (IA) is a DC power supply during system operation, (3) and (3B) are diodes for backflow prevention, and (9) is a Main battery for backup (
6) is a memory circuit that is taken apart in the event of a power outage.

Next, the operation of the other conventional device mentioned above will be explained. When the system is in operation, the memory circuit (6)
is the DC power supply (l^) during system operation and the rediode (
3B). At this time, the voltage reduction check circuit (7) compares the voltage of the main battery (9) with the voltage of the DC power supply (IA) and the value set by the voltage dividing resistor (71A). ) outputs °1" when the voltage is normal.

Next, in the event of an abnormal power outage, the DC power supply (IA) drops, so the memory circuit (6) goes into a backup mode, and power is supplied from the main battery (9) through the diode (3). Normally, the discharge characteristics of a battery draw a curve as shown in Figure 9, so as the battery continues to discharge, the battery voltage begins to drop at a certain point, and eventually reaches the backup limit voltage Vh of the memory circuit, and the memory circuit The contents held in (6) are destroyed. To prevent this, the battery drop detection voltage V of the voltage drop check circuit (7) is set before the backup limit voltage Vh, and the DC power supply (IA
) is normal, the system outputs the output of the voltage reduction check circuit (7) as "0" when the main battery (
9) It becomes possible to know when to replace.

[Problem to be solved by the invention]

Conventional battery backup devices were configured as described above, and because the time it takes for the battery voltage to begin to drop and reach the memory backup limit voltage is very short, battery voltage drop detection was performed. Due to the short guaranteed backup time and errors in the detection voltage range, it is difficult to predict the backup time after detection, and if there is a delay in replacing the battery when an alarm occurs, the backup contents will be destroyed. there were.

Furthermore, due to the discharge characteristics of a single battery, the voltage reduction indicator LED lights up, and then the retention limit indicator LED lights up.
Since the time it takes for D to turn on is short, the battery cannot be replaced during that time, resulting in problems such as the contents of the memory circuit not being retained.

This invention was made to solve the above-mentioned problems, and it maintains backup for a certain period of time even after a battery voltage drop is detected, and also reduces the backup time after a battery voltage drop is detected due to a detection voltage error. The purpose is to obtain a battery backup device that can accurately predict.

Another object of the present invention is to provide a battery backup device that can display a decrease in battery voltage and indicate that the voltage has decreased below a value necessary to retain the contents of a memory circuit.

[Means to solve the problem]

A battery backup device according to the present invention has a main battery that retains the contents of a memory circuit that stores programs and various data, a voltage test circuit that tests the voltage of the main battery, and a discharge characteristic different from that of the main battery. , an auxiliary battery connected in parallel to the main battery to supply power to the memory circuit, and based on the test results of the voltage test circuit, backs up the voltage reduction of the main battery until the main battery is replaced. It is configured to be assisted by an auxiliary battery.

In addition, another battery backup device according to the present invention includes a main battery that retains the contents of a memory circuit that stores programs and various data, a voltage test circuit that tests the voltage of the main battery, and a voltage test circuit that is different from the main battery described above. an auxiliary battery having a discharging characteristic and connected in parallel with the main battery to supply power to said memory circuit; and a voltage reduction indicating that the voltage supplied to said memory circuit has decreased below a preset voltage; a display section; and a retention limit display section for displaying that the voltage supplied to the memory circuit has decreased below a voltage value necessary to retain the contents of the memory circuit, and The configuration is such that it backs up the decrease in voltage of the main battery, uses the auxiliary battery to assist until the main battery is replaced, and displays the time to replace the battery.

[Effect]

The auxiliary battery according to the present invention guarantees backup for a certain period of time or more after the high-voltage main battery finishes discharging and the voltage drops to detect a state of electricity storage.

In addition, each of the voltage reduction and retention limit display sections in another invention displays the voltage decrease of the main battery, and also displays the limit of the backup voltage value for retaining the contents of the memory circuit to notify the battery backup state in advance. be able to.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 shows a block configuration diagram of the device of this embodiment. In FIG. 1, (1) is an AC power supply that supplies power to the memory circuit (6) during normal operation, and (2) is an AC power supply that supplies power to the memory circuit (6) during normal operation. AC/D converts AC voltage to DC
C converter, (3) (3^), (3B), (3G) are diode 1 and diode 2 to prevent reverse current flow.
, diode 3, diode 4, (4) (4^),
(4B) is resistor 1, resistor 2, resistor 3, (5) is a capacitor that holds the contents of the memory circuit (6) for a certain period of time when converting the power supply to battery backup when the AC power supply (1) is off, (°6 ) is a memory circuit made of a volatile semiconductor memory element, and (9) is a memory circuit (6) when the power is turned off.
) The main battery with the higher voltage that supplies power to (9^
) is an auxiliary battery with a lower voltage than the main battery (9); (7) is a voltage reduction check circuit that checks whether the voltage of the main battery (9) has dropped to the voltage of the auxiliary battery (9^); 7^) is a retention limit check circuit that checks the limit of whether the voltage of the main battery (9) and auxiliary battery (9A) can retain the contents of the memory circuit (6); (8) is the main battery ( 9) is the main battery (9).Voltage reduction LED indicates that the voltage has decreased to the voltage of the auxiliary battery (9A).(8A) is the main battery (9)
and the voltage of the auxiliary battery (9A) is the memory circuit (6)
L for displaying the retention limit to notify that the contents cannot be retained.
It is ED.

Figure 2 shows the discharge characteristics of the main battery (9), which has the higher voltage.The horizontal axis shows time and the vertical axis shows voltage. It shows the transition. In the same figure, the voltage maintains a constant voltage VC until 16 hours, and after time Tc, the voltage gradually decreases.
After time Th, the voltage becomes vA, indicating that the remaining life of the battery is 16 hours. When time Th reaches time, the voltage becomes Vh, and the contents of the memory circuit (6) can no longer be held.

Also, Figure 3 shows the auxiliary battery (9A) with lower voltage.
This is a discharge characteristic diagram of , with time on the horizontal axis and voltage on the vertical axis, representing the transition of the voltage supplied from the auxiliary battery (9^). The voltage is a constant voltage V until Th time.
A is maintained, and after Th time the voltage gradually decreases until Th
After a period of time, the voltage becomes vh, and the contents of the memory circuit (6) can no longer be held.

Figure 4 shows the main battery (9) and auxiliary battery (9A
) are connected in parallel, with time on the horizontal axis and voltage on the vertical axis, with both batteries (9)
(9A) represents the transition of the voltage supplied from (9A). At first, voltage is supplied from the main battery (9) with higher voltage, and the voltage maintains a constant voltage Vc until time Tc, and after time TC, the voltage gradually decreases, and when time reaches Th, the voltage decreases. It becomes vA. From this point on, power is also supplied from the auxiliary battery (9^) with lower voltage, maintaining a constant voltage vA until Th time.
After time, the voltage gradually decreases, and after the rh time, the voltage becomes vh, and the contents of the memory circuit (6) can no longer be held.

Next, the operation of the above embodiment will be explained. To retain the contents of the memory circuit (6), turn on the AC power (1).
Either the main battery (9) or the auxiliary battery (9A) can be used as a backup power supply.

When retaining the contents of the memory circuit (6) by this battery backup, as shown in Figure 1, the main battery (9) with the higher voltage is first
), and when the voltage drops until it becomes the same as the voltage of the auxiliary battery (9A) with lower voltage,
Turn on the voltage decrease display LED (8) to notify the voltage decrease. And the auxiliary battery with lower voltage (9A
) is also supplied with power (point TAI shown in Figure 3),
The voltage further decreases and the holding limit voltage check circuit (7A
), and when the holding voltage of the contents of the memory circuit (6) is lower than the holding voltage, the holding limit display LED (
8A) is lit to indicate that the contents of the memory circuit (6) cannot be retained.

When both the voltage decrease display LED (8) and the retention limit display LED (8A) are not lit, it indicates that the contents of the memory circuit (6) are retained. If only the voltage decrease display LED (8) above is lit, if the main battery (9) with higher voltage is replaced, the voltage decrease display LED (8) will be lit again. It disappears. L E D (8
) and retention limit display LED (8A) are both lit, if you carelessly turn off the AC power (1),
The contents of the memory circuit (6) will be destroyed, indicating that battery support is immediately required. However, after the voltage reduction display LED turns on, the holding limit display LED turns on.
There is enough time until L E D (8A) lights up, so replace the battery without destroying the contents of the memory circuit (6) while only the voltage decrease indicator L E D (8) lights up. It can be performed.

In the above embodiment, two display units for notifying the battery backup state are provided, but it is also possible to provide only one of them.

FIG. 4 shows a block configuration diagram of another embodiment of the present invention, in which (IA) is a DC power supply that supplies power during system operation, and (6) is power from the DC power supply (IA). (7) is a voltage reduction check circuit formed by a comparator that detects a battery voltage drop;
) is the main battery (9A) that backs up the battery voltage drop detection of the voltage drop check circuit (7); and the auxiliary battery (3) that backs up the voltage drop check circuit (7) after the battery voltage drop is detected.
(3A), (3B) are diodes that prevent reverse current flow, (71A), (71B) (71G)
(710) are voltage dividing resistors for setting the input voltage of the voltage reduction check circuit (7).

Next, the operation of the other embodiment of the invention described above will be described. First, when the system is operating the memory circuit (6)
Power is supplied from the DC power source (IA) via the diode (3B). Next, the system
When the function of A) is stopped due to a power outage, power is first supplied to the memory circuit (6) from the high voltage main battery (9) via the diode (3) to perform backup. Incidentally, the guaranteed backup time according to the specifications is set to the backup time of this main battery (9). When the main battery (9) finishes discharging, the battery voltage drops rapidly and reaches the low battery detection voltage VA (
(See Figure 5). When DC power (IA) is supplied in this state, the voltage reduction check circuit (7) outputs "0" and gives an alarm to the system. In addition, as the power outage continues, the voltage of the main battery (9) further decreases, and the auxiliary battery (9)
When the rated voltage of A) is reached, the auxiliary battery (9
A) discharge begins.

Then, the backup time (t1 from Tc to Th
), the backup limit voltage vh is reached. If there is no auxiliary battery (9A), the backup voltage will reach the backup limit voltage vh within the backup time (tz between Tc and TAL), so the guaranteed backup time after the backup voltage drop is detected is short, and furthermore, it is difficult to guess. This will be difficult.

In addition, the battery low detection voltage vA is the main battery (9)
and the auxiliary battery (9A), or any value in between, and the battery backup limit voltage h must be set lower than the voltage of the auxiliary battery (9A).

(Effects of the Invention) As described above, according to the present invention, in addition to the main battery that retains the memory contents of the memory circuit in the event of an abnormality such as a power outage, an auxiliary battery that has different discharge characteristics from the main battery is connected in parallel to the main battery. Since the main battery is connected to the main battery, there is enough time to replace the main battery, and it is possible to prevent the contents of the memory circuit from being destroyed.

In addition, according to this invention, the battery backup status is displayed step by step in advance because the display is configured to display the main battery voltage decrease and the retention limit of the memory circuit by the main battery and the auxiliary battery. This has the effect that main battery replacement, maintenance, etc. can be performed reliably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a battery backup device according to an embodiment of the present invention, FIGS. 2 and 3 are battery discharge characteristic diagrams, and FIG. 4 is a battery backup device according to another embodiment of the invention. FIG. 5 is a battery discharge characteristic diagram in the embodiment shown in FIG. 4,
Fig. 6 is a block diagram of a conventional battery backup device, Fig. 7 is a battery discharge characteristic diagram of the conventional device, Fig. 8 is a block diagram of another conventional battery backup device, and Fig. 9 is the same as shown in Fig. 8. 1 shows a battery discharge characteristic diagram of a conventional device. (1) ... AC power supply (IA) ... DC power supply (2) ... A C70C converter (3) (3A), (3B), (3C) ... Diode (4) (4^) , (4B)...Resistance (5
) ... Capacitor (6) ... Memory circuit (7
)...Voltage decrease check circuit (7A)...Holding limit voltage check circuit (8)...LE for voltage decrease display
D (8A)...LED for displaying engagement limit (9)...Main battery (9A)...Auxiliary battery In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) Equipped with a main battery that holds the contents of a memory circuit that stores programs and various data, and a voltage test circuit that tests the voltage of the main battery, and detects a decrease in battery voltage based on the test results of the voltage test circuit. What is claimed is: 1. A battery backup device for backing up the battery, comprising: an auxiliary battery having a discharge characteristic different from that of the main battery and connected in parallel to the main battery to supply power to the memory circuit. (2) The voltage test circuit is configured to perform a voltage test by providing a battery voltage reduction detection setting value between each voltage value of the main battery and the auxiliary battery. Battery backup device as described. (3) It is equipped with a main battery that holds the contents of a memory circuit that stores programs and various data, and a voltage test circuit that tests the voltage of the main battery, and the voltage of the main battery is reduced based on the test results of the voltage test circuit. In the battery backup device for backing up the memory circuit, the auxiliary battery has discharge characteristics different from the main battery and is connected in parallel to the main battery to supply power to the memory circuit, and the voltage supplied to the memory circuit is preset. and a retention limit display section that indicates that the voltage supplied to the memory circuit has decreased below a voltage value necessary to retain the contents of the memory circuit. A battery backup device comprising: