JPH04232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a communication terminal device that is normally powered by a commercial power source and is powered from a backup power source in the event of a power outage. The present invention relates to a monitoring circuit for making an accurate judgment.

Conventionally, with communication terminal devices such as public telephones and button telephones that are powered by commercial power in addition to local power, the terminal device becomes unusable, or even if it does not become unusable, during a commercial power outage. There was a risk that the quality of the service would deteriorate significantly.

Therefore, measures are being taken to ensure the same level of service by installing a backup power source and using it in the event of a commercial power outage. As a backup power source for terminal devices, sealed lead-acid batteries and nickel batteries are recommended.
Secondary batteries such as cadmium storage batteries are widely used because they are small and can be used repeatedly. There is no way to accurately detect when the performance of the secondary battery deteriorates, so when it is installed in equipment that requires high reliability, it has been necessary to periodically remove it earlier than its estimated lifespan. They are used either to give a positive impression or to count the number of times charging and discharging are repeated and determine when to replace them based on the counting results.

In addition, a simple method for estimating battery performance deterioration is to take out the battery installed in the device at a predetermined time and measure it under certain test conditions, and then calculate the battery capacity by There is a way to tell if it is below the specified value. However, when the secondary battery is installed in the terminal device such as a public telephone, the temperature range of the location where the terminal device is installed is wide ranging from low to high temperatures. The lifespan of the installed battery varies, making it difficult to estimate, and the equipment itself may fail due to other causes and be replaced, so it may not be left in the same location for a long period of time. Difficult to manage.

Furthermore, because commercial power supply power outages occur only a few times a year, secondary batteries that are used only at those times are not charged and discharged in a cyclical manner, and most of the batteries are in a state of charge that is sufficient to replenish their self-discharge. This makes it difficult to set the battery replacement cycle. In addition, in the conventional method of estimating battery performance deterioration, it is necessary to remove the battery from the terminal device once,
Additionally, it takes a long time to determine the presence or absence of deterioration, so it is only used in a limited number of devices.

Therefore, when the secondary battery is installed as a backup power source for the terminal device such as a public telephone, the maintenance cost including maintenance costs is too high, and it cannot be used.

The present invention has been made in order to solve the conventional technical problems as described above, and therefore, an object of the present invention is to maintain the terminal device even when a secondary battery is installed as a backup power source for the terminal device. An object of the present invention is to provide a monitoring circuit for a standby power source for a terminal device, which enables cost reduction.

To achieve the above object, a monitoring circuit according to the present invention includes a secondary battery as a backup power source, a variable charging circuit capable of trickle charging or rapid charging of the battery, and a forced discharge of the secondary battery. The device includes a forced discharge circuit, a detection circuit for a discharge current during forced discharge, a terminal voltage monitoring circuit for the secondary battery, and a control unit, and the control unit controls the terminal voltage of the secondary battery to be a reference voltage. When the voltage monitoring circuit detects that the voltage has dropped to below, the operation of the variable charging circuit, which had been trickle charging the secondary battery, is switched from trickle charging to rapid charging, and the voltage is forced to rapidly charge for a predetermined period of time. After that, the secondary battery is discharged for a predetermined time by the forced discharge circuit,
The present invention is characterized in that performance deterioration of the secondary battery is determined by detecting the presence or absence of a discharge current using the current detection circuit.

Next, an embodiment of the present invention will be described with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention. In the same figure, 1 and 2 are commercial power input terminals,
3 is a power supply circuit that converts input AC power into DC power and outputs it, 4 is a power load circuit, 5 and 11 are each a timer circuit, and 6 is used for trickle charging to charge with a minute current value or for large current. 7 is a secondary battery consisting of a plurality of cells; 8 is a switching circuit; 9 is a current detection circuit;
10 is a forced discharge circuit, 12 is a control circuit section, 13 is a commercial power supply power failure detection circuit, and 14 is a terminal voltage monitoring circuit for monitoring whether the terminal voltage of the secondary battery 7 is below a reference voltage. These are all installed in the terminal device. In addition, the routes shown by solid lines are power lines, and the routes shown by dotted lines are control signal lines.

Next, the circuit operation will be explained. When a commercial power source (not shown) is turned on, the AC power input to the commercial power input terminals 1 and 2 is converted into DC power by the power supply circuit 3.
It is smoothed and supplied to the DC power load circuit 4 via power lines a and b. On the other hand, DC power from the power supply circuit 3 passes through a timer circuit 5 and a variable charging circuit 6 to charge a secondary battery 7.

This charging is normally performed by trickle charging using a minute current, and in this state, both the switching circuit section 8 and the forced discharge circuit 10 are in an OFF state. Here, switching of the charging format in the variable charging circuit 6, that is, switching from trickle charging to quick charging, or vice versa, is controlled by the timer circuit 5. On/off of the forced discharge circuit 10 is controlled by a timer circuit 11. Further, the on/off switching of the switching circuit section 8 is directly controlled by the control circuit section 12.

If the commercial power supply fails, the power failure detection circuit 13 detects this and sends a power failure detection signal to the control circuit section 12 via the signal line A. At the same time as receiving the signal, the control circuit unit 12 sends a control signal via the signal line 7, turns the switching circuit unit 8 on, and supplies power from the secondary battery 7 to the load circuit 4.

Monitoring the condition of the secondary battery 7 (monitoring the terminal voltage) is as follows:
This is done by detecting the terminal voltage of the secondary battery 7 in the terminal voltage monitoring circuit 14 at all times or when using the terminal device, and comparing it with a built-in reference voltage. The terminal voltage of the secondary battery 7 may be detected during trickle charging, during forced discharging, or when the variable charging circuit 6 and the forced discharging circuit 10 are in the OFF state.

When the terminal voltage monitoring circuit 14 detects that the detected terminal voltage of the secondary battery 7 is lower than the reference voltage, it sends a control signal to the control circuit section 12 via the signal line C. After receiving the signal, the control circuit unit 12 detects whether or not there is a power outage in the commercial power supply by using the power outage detection circuit 1.
3, and when there is a power outage, the control signal from the terminal voltage monitoring circuit 14 is ignored. When there is no power outage, a control signal is sent via signal line D to activate the timer circuit 5. That is, the timer circuit 5 switches the charging format of the variable charging circuit 6 from the trickle charging format to the quick charging format, and quickly charges the secondary battery 7.

The charging time can be arbitrarily changed by arbitrarily setting the timer value of the timer circuit 5, but in this case, since the purpose is not to completely charge the secondary battery 7, a relatively short charging time is sufficient.

In this way, when the quick charging is completed by the relatively short charging time set by the timer circuit 5,
This time, the control circuit section 12 sends out a control signal via the signal line E to activate the timer circuit 11. That is, the timer circuit 11 turns on the forced discharge circuit 10, thereby forcing the secondary battery 7 to discharge. The discharging time can be arbitrarily changed by arbitrarily setting the timer value of the timer circuit 11, but the discharging time is set so that the product of the discharging current value and the discharging time is smaller than the product of the quick charging current value and the charging time. settings need to be made.

Note that the forced discharge circuit 10 includes a constant current circuit,
Either fixed resistor may be used, but it is best to choose a current value with a discharge current value of about 0.1C to 2C.

When the forced discharge circuit 10 starts discharging, the discharge current from the secondary battery 7 is monitored by the current detection circuit 9,
If no current flows, a control signal is sent to the control circuit unit 12 via the signal line. Control circuit section 12
Based on this signal, it is determined that the performance of the secondary battery 7 has deteriorated. If current is flowing, the secondary battery 7 is discharged until the predetermined discharge time set by the timer circuit 11 ends, and then the terminal voltage of the secondary battery 7 is checked by the terminal voltage monitoring circuit 14. If the terminal voltage of the secondary battery 7 is equal to or higher than the reference voltage, the forced discharge circuit 10
is turned off, the timer circuit 5 is activated again, the variable charging circuit 6 is shifted to trickle charging operation, and the normal operating state is returned to trickle charging the secondary battery 7. On the other hand, if the terminal voltage of the secondary battery 7 is equal to or lower than the reference voltage, it is determined that the performance of the secondary battery 7 has deteriorated.

As explained above, according to the monitoring circuit for a backup power source for a terminal device according to the present invention, there is no need to take out the secondary battery as a backup power source from the terminal device.
By automatically detecting the terminal voltage of the secondary battery within the terminal device itself and detecting the drop in voltage below the reference value and the presence or absence of discharge current during forced discharge following rapid charging, It is possible to automatically and easily determine in a short time whether there is a normal decrease in battery capacity due to the use of a secondary battery or whether the performance of the secondary battery itself has deteriorated. Therefore, even if a secondary battery is installed as a backup power source in a communication terminal device, it becomes easy to manage the battery, and it is possible to know when to replace it appropriately.
Therefore, the present invention has the advantage that maintenance and operational costs can be expected to be significantly reduced.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. Symbol explanation, 1, 2...Commercial power input terminal, 3...
...Power supply circuit, 4...Power load circuit, 5...Timer circuit, 6...Variable charging circuit, 7...Secondary battery,
8...Switching circuit section, 9...Current detection circuit, 1
0... Forced discharge circuit, 11... Timer circuit, 1
2... Control circuit section, 13... Power outage detection circuit, 14
...Terminal voltage monitoring circuit.

Claims (1)

[Claims] 1. A secondary battery as a backup power source, a variable charging circuit that can perform trickle charging or rapid charging of the battery, a forced discharge circuit that forcibly discharges the secondary battery, and detection of discharge current during forced discharge. a circuit, a terminal voltage monitoring circuit for the secondary battery,
and a control unit, when the voltage monitoring circuit detects that the terminal voltage of the secondary battery has decreased below a reference voltage, the control unit trickle charges the secondary battery until then. The operation of the variable charging circuit is switched from trickle charging to rapid charging, and after forced rapid charging for a predetermined time, the secondary battery is discharged for a predetermined time by the forced discharge circuit, and the current detection circuit detects the presence or absence of discharge current. 1. A monitoring circuit for a standby power source for a terminal device, characterized in that performance deterioration of a secondary battery is determined by detecting the deterioration in performance of a secondary battery.