Backup power supply device and electronic apparatus

Abstract

The present invention ensures time from the start of a voltage decrease of a voltage conversion circuit to backup voltage loss when a battery and the voltage conversion circuit are used in combination as a power supply for backing up a voltage of a semiconductor memory. The present invention is provided with a voltage conversion circuit that converts a voltage of a secondary battery into two different backup voltages required by a semiconductor memory, and is also provided with a voltage monitoring circuit that monitors the voltage of the battery connected to the input of the voltage conversion circuit. Using a voltage at which there is sufficient remaining battery capacity to ensure time for maintenance as a threshold value, a switch to the backup voltages is performed and a voltage decrease warning is displayed.

Description

Backup Power Supplies and Electronic Equipment

[0001] The present invention relates to a device that uses a secondary battery to form a backup power supply.

[0002] In electronic devices having semiconductor memories, in order to maintain the information stored in the semiconductor memory even if the main power source is lost, it is common to incorporate a circuit that backs up the semiconductor memory using a power source other than the main power source, such as a primary battery or a secondary battery, as a backup power source. When using a primary battery for backup, alkaline batteries or lithium batteries are generally used, and when using a secondary battery for backup, nickel-metal hydride batteries are generally used for safety reasons.

[0003] A backup battery is connected in parallel to the DC power supply rectified and smoothed from the commercial power supply inside the device to apply backup voltage to the semiconductor memory. To prevent current from flowing into the backup battery while the DC power supply is operating, a reverse current prevention diode is connected between the memory's power supply terminal and the backup battery. However, if the reverse current prevention diode fails, the backup battery may be charged from the power supply terminal, posing a risk of battery destruction. Furthermore, the backup battery's voltage may drop, preventing backup operation during a power outage. To address this issue, the following method has been disclosed.

[0004] The backup battery voltage is monitored by a monitoring circuit, and if the voltage exceeds a set upper limit in the event of a malfunction, an alarm is issued and repair measures are taken to prevent the battery from exploding due to charging the primary battery.The voltage of the primary battery is also compared with a set lower limit voltage, and if the battery voltage drops below this value, it means that the primary battery is depleted, so a depletion alarm is output and a notice is given that the battery should be replaced.This type of technology is described, for example, in Patent Document 1 listed below.

[0005] Patent No. 2576896

[0006] When backing up semiconductor memory, voltage setting is important. When using a typical primary or secondary battery and diode, to ensure reliable backup operation over a wide temperature range, for example, from 0°C to 85°C, it is desirable to be able to freely set the battery voltage while taking into account the change in forward voltage with respect to temperature of the diode. However, when a circuit that performs voltage conversion using an electronic circuit is installed, there is an issue that there is not enough time between the voltage monitoring alarm and repair or replacement.

[0007] In order to solve the above problems, one embodiment of the present invention provides a voltage conversion circuit that converts the voltage of a secondary battery into the backup voltage required by a semiconductor memory, and a voltage monitoring circuit that monitors the voltage of a battery connected to the input of the voltage conversion circuit, and a method of lowering the output voltage of the voltage conversion circuit according to the state of battery consumption to a voltage that can maintain the information in the semiconductor memory while still activating an alarm.

[0008] According to the present invention, by setting a voltage value for the battery's depleted state when there is sufficient time between the issuance of an alarm and repair or replacement, it becomes easier to prevent information loss in the semiconductor memory.

[0009] FIG. 1 is a configuration diagram of a first embodiment of a backup power supply device according to an embodiment of the present invention. FIG. 2 is a diagram showing a specific configuration of the first embodiment of a backup power supply device according to an embodiment of the present invention. FIG. 3 is a configuration diagram of a second embodiment of a backup power supply device according to an embodiment of the present invention. FIG. 4 is a diagram showing a specific configuration of the second embodiment of a backup power supply device according to an embodiment of the present invention. FIG. 5 is a configuration diagram of a third embodiment of a backup power supply device according to an embodiment of the present invention.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the description of the embodiments, and various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed in this specification. Furthermore, in all drawings used to explain the present invention, components having the same functions are given the same reference numerals, and repeated explanations thereof may be omitted.

[0011] A typical backup power supply refers to an uninterruptible power supply such as a UPS (Uninterruptible Power Supply) that maintains the operation of the entire system, but the backup power supply defined here is a power supply that backs up the power supply for part of a device in order to prevent the loss of position information data when the system stops operating, such as data retention in semiconductor memory or information from encoders that determine the position of mechanically operating devices, when the system suddenly stops operating or stops for equipment maintenance, etc.

[0012] 1 is a diagram showing the overall configuration of a backup power supply according to one embodiment of the present invention. Electronic device 9 includes system power supply 10, diode 12, semiconductor memory 11, semiconductor memory power terminal 19, power terminal charging power output terminal 13, backup power input terminal 14, memory voltage monitoring circuit 205, and memory alert display circuit 206. Electronic device 9 has system power supply 10 built in, and outputs a voltage of 3.6 V to terminal 19, for example, setting the voltage capable of driving semiconductor memory 11 to 3.6 V to 2.7 V.

[0013] Backup power input terminal 14 is connected to semiconductor memory power terminal 19 via diode 12, and a voltage lower than that of terminal 19, for example, a voltage of 3.5 (V), is input. A voltage of 3.3 (V), for example, is supplied to power terminal charging power output terminal 13. Memory voltage monitoring circuit 205 is composed of voltage detection terminal 209, ground terminal 208, and memory alert control terminal 207, and the detection voltage of terminal 209 is set to 2.75 (V).

[0014] The backup power supply device 1 includes a secondary battery 3, a voltage conversion circuit 6, a power supply input terminal 7, a backup output terminal 8, and a battery voltage monitoring circuit 201. The backup power supply device 1 further includes a charging circuit 2. The charging circuit 2 charges the secondary battery 3. The secondary battery 3 is a sulfide-based all-solid-state battery. The voltage conversion circuit 6 includes a secondary battery input terminal 18 and an output voltage control terminal 202.

[0015] The voltage conversion circuit 6 may convert the voltage of a primary battery into two different predetermined voltages, or may convert the voltage of a secondary battery into two different predetermined voltages. The battery voltage monitoring circuit 201 is composed of a voltage detection terminal 204 and a common ground terminal 203. The battery voltage monitoring circuit 201 monitors the input voltage of the voltage conversion circuit 6.

[0016] Next, the operation will be described. When the electronic device 9 is operating, a predetermined voltage is supplied from the power input terminal 7 of the backup power supply device 1 to the charging circuit 2, which charges the secondary battery 3. During charging, voltage is input from terminal 18 to the voltage conversion circuit 6, terminal 202 is open, and 3.5 (V) is output to terminal 8 via the voltage conversion circuit 6. When the electronic device 9 is not operating, the charging circuit 2 does not perform a charging operation, and the voltage of the secondary battery 3 is input to terminal 18, and the same operation is performed.

[0017] The 3.5 V supplied from terminal 14 is reduced by the forward voltage drop (hereinafter referred to as VF) of diode 12, and when VF=0.7 V, for example, 2.8 V is supplied to semiconductor memory 11, preventing data loss from the semiconductor memory. In this case, because this exceeds the detected voltage of 2.75 V at voltage detection terminal 209 of memory voltage monitoring circuit 205, no alarm information is displayed from memory alert display circuit 206, which is controlled via terminal 207.

[0018] As the backup operation from the secondary battery 3 continues, the voltage of the secondary battery 3 gradually decreases, and when it falls below the voltage value set inside the battery voltage monitoring circuit 201, the terminal 202 is controlled from the open state to the ground state.

[0019] When terminal 202 changes from an open state to a grounded state, voltage conversion circuit 6 controls the voltage value of output terminal 8 to change from 3.5 (V) to 3.4 (V). The voltage supplied to semiconductor memory 11 changes from 2.8 (V) to 2.7 (V), backup operation continues, and because the operation of memory voltage monitoring circuit 205 is below the detected voltage of 2.75 (V) at terminal 209, an alarm is displayed by memory alert display circuit 206 controlled via terminal 207.

[0020] The warning display continues until the remaining capacity of the secondary battery 3 is completely depleted, so by appropriately setting the voltage drop detection value for the secondary battery 3, it is possible to reliably prevent the loss of information in the semiconductor memory. The operation of the battery voltage monitoring circuit 201 will be explained in detail using Figure 2.

[0021] 2 is a diagram showing the specific configuration of a first embodiment of a charging device according to the present invention. A battery voltage monitoring circuit 201 has resistors 220 and 221, a reference voltage source 222, a voltage comparator 223, an N-channel MOS transistor 224, a ground terminal 203, a voltage detection terminal 204, and an output voltage control terminal 202.

[0022] The voltage input from voltage detection terminal 204 is divided by resistors 220 and 221, and compared with the voltage of reference voltage source 222. If it is smaller, the output of voltage comparator 223 is on, and if it is larger, the output is off. For example, if the voltage of the reference voltage source is set to 1.0 (V) and the detection voltage of the secondary battery 3 is set to 2.2 (V), and the ratio of resistors 220 and 221 is 6:5, when the voltage of the secondary battery 3 is high at 2.3 (V), the divided voltage value will be 1.045 (V), the output of voltage comparator 223 will be off, and the drain terminal of N-channel MOS transistor 224, i.e., output voltage control terminal 202, will be in the open state.

[0023] When the voltage of the secondary battery 3 is low at 2.1 (V), the divided voltage value becomes 0.954 (V), the output of the voltage comparator 223 is turned on, and the drain terminal of the N-channel MOS transistor 224, i.e., the output voltage control terminal 202, is grounded.

[0024] 3 is a diagram showing the overall configuration of a backup power supply according to a second embodiment of the present invention. Electronic device 9 comprises system power supply 10, diode 12, semiconductor memory 11, semiconductor memory power terminal 19, power terminal charging power output terminal 13, and backup power input terminal 14. Electronic device 9 has system power supply 10 built in, which outputs a voltage of, for example, 3.6 V to drive semiconductor memory 11. Backup power input terminal 14 is connected to semiconductor memory power terminal 19 via diode 12, and receives a voltage lower than that of terminal 19, for example, 3.5 V. Power terminal charging power output terminal 13 is supplied with a voltage of, for example, 3.3 V.

[0025] The backup power supply device 1 comprises a secondary battery 3, a voltage conversion circuit 6, a battery voltage monitoring circuit 201, a battery alert display circuit 210, a power input terminal 7, and a backup output terminal 8. The backup power supply device 1 further comprises a charging circuit 2. The charging circuit 2 charges the secondary battery 3. The secondary battery 3 is composed of a sulfide-based all-solid-state battery. The voltage conversion circuit 6 comprises a secondary battery input terminal 18 and a backup output terminal 8. The battery voltage monitoring circuit 201 comprises a voltage detection terminal 204 and a ground terminal 203. The battery alert display circuit 210 comprises an alert display power terminal 212. In addition, the circuit that displays a drop in battery voltage comprises a light-emitting diode and a drive circuit, and the drive circuit intermittently drives the light-emitting diode.

[0026] Next, the operation will be described. When the electronic device 9 is operating, a predetermined voltage is supplied from the power input terminal 7 of the backup power supply 1 to the charging circuit 2, which charges the secondary battery 3. During charging, the voltage is input from terminal 18 to the voltage conversion circuit, terminal 202 is open, and 3.5 V is output to terminal 8 via the voltage conversion circuit 6. When the electronic device 9 is not operating, the charging circuit 2 does not charge, and the voltage of the secondary battery is input to terminal 18, and the same operation is performed. The 3.5 V supplied from terminal 14 is reduced by the forward drop voltage (hereinafter referred to as VF) of the diode 12. For example, if VF = 0.7 V, 2.8 V is supplied to the semiconductor memory 11, preventing data loss in the semiconductor memory.

[0027] As backup operation from the secondary battery 3 continues, the voltage of the secondary battery 3 gradually drops. When it falls below a voltage value set internally in the battery voltage monitoring circuit 201, the terminal 202 is controlled to change from an open state to a grounded state. When the terminal 202 changes from an open state to a grounded state, the battery alert display circuit 210 displays a low battery capacity alert. The low battery capacity alert display continues until the remaining capacity of the secondary battery 3 is completely depleted, so by appropriately setting the low voltage detection value for the secondary battery 3, it is possible to reliably prevent the loss of information in the semiconductor memory. The operation of the battery voltage monitoring circuit 201 is the same as that already explained in FIG. 2, and therefore a detailed explanation will be omitted. The operation of the battery alert display circuit 210 will be explained using FIG. 4.

[0028] 4 is a diagram showing a specific configuration of a second embodiment of the charging device according to the present invention. The battery alert display circuit 210 is composed of resistors 213 and 214, an NPN transistor 215, a PNP transistor 216, a capacitor 217, a light-emitting diode 218, a terminal 202, and a terminal 212.

[0029] When terminal 202 is open, the battery alert display circuit is inactive. When terminal 202 is grounded, the voltage input from terminal 212 starts charging capacitor 217 via resistor 213. When capacitor 217 is charged and the voltage between the base and emitter of transistor 215 exceeds 0.7 V, transistor 215 turns on and a base current flows through transistor 216. As a result, a current flows from the collector of transistor 216 to terminal 202 via light-emitting diode 218 and resistor 214, causing light-emitting diode 218 to light up.

[0030] After the light-emitting diode 218 lights up, the charge in the capacitor 217 is discharged, causing the transistor 215 to turn off, and at the same time, the transistor 216 turns off, turning off the light-emitting diode 218. After the light-emitting diode 218 turns off, charging of the capacitor 217 begins again with the input voltage from the terminal 212. As explained above, the light-emitting diode 218 continues to flash, and the battery alert display circuit 210 is activated.

[0031] Figure 5 is a diagram showing the overall configuration of a backup power supply device according to a third embodiment of the present invention. Since the components in Figure 5 are the same as those in Figure 3, their explanation will be omitted, and only the differences from Figure 3 will be explained. The connection position of the power supply terminal 212 of the battery alert display circuit 210 is different, and in Figure 5 it has been changed to the input terminal 18 of the voltage conversion circuit 6.

[0032] An example of an electronic device 9 equipped with a backup power supply is an absolute encoder used in an industrial robot. An absolute encoder is mounted on the motor (e.g., servo motor) of the robot's operating axis, and by supplying backup power to the encoder using a battery or the like, the movement of the motor is constantly monitored even when the power to the controller is cut off, enabling smooth startup without returning to the origin when the system is started or when recovering from an emergency stop.

[0033] In any of the embodiments described above, the warning display by the memory alert display on the system side or the battery alert display on the backup battery side will continue until the remaining capacity of the secondary battery 3 is completely depleted, so by appropriately setting the voltage drop detection value of the secondary battery 3, it is possible to reliably prevent the loss of information in the semiconductor memory.

[0034] Furthermore, the technology according to this embodiment can provide a charge / discharge system with excellent energy efficiency, which contributes to the achievement of "9. Build resilient infrastructure, promote inclusive and sustainable industrialization, promote innovation and foster resilience" and "11. Make cities and towns inclusive and sustainable" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0035] Although various embodiments have been described above in detail, the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments are detailed descriptions of the entire system in order to clearly explain the present invention, and the present invention is not necessarily limited to a system including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0036] 1... Backup power supply device, 2... Charging circuit, 3... Secondary battery, 6... Voltage conversion circuit, 201... Battery voltage monitoring circuit, 210... Battery alert display circuit

Claims

1. A backup power supply device comprising: a primary battery; a voltage conversion circuit that converts the voltage of the primary battery into two different predetermined voltages; and a voltage monitoring circuit that monitors the input voltage of the voltage conversion circuit, wherein the voltage of the voltage conversion circuit is switched by the voltage monitoring circuit.

2. A backup power supply device comprising: a secondary battery; a charging circuit for charging the secondary battery; a voltage conversion circuit for converting the voltage of the secondary battery into two different predetermined voltages; and a voltage monitoring circuit for monitoring the input voltage of the voltage conversion circuit, wherein the voltage of the voltage conversion circuit is switched by the voltage monitoring circuit.

3. A backup power supply device according to claim 2, wherein the secondary battery is a sulfide-based all-solid-state battery.

4. A backup power supply device comprising: a primary battery; a voltage conversion circuit that converts the voltage of the primary battery into a predetermined voltage; a voltage monitoring circuit that monitors the input voltage of the voltage conversion circuit; and a circuit that displays a voltage drop of the primary battery monitored by the voltage monitoring circuit.

5. A backup power supply device comprising: a secondary battery; a charging circuit for charging the secondary battery; a voltage conversion circuit for converting the voltage of the secondary battery to a predetermined voltage; a voltage monitoring circuit for monitoring the input voltage of the voltage conversion circuit; and a circuit for indicating a voltage drop of the secondary battery monitored by the voltage monitoring circuit.

6. A backup power supply device according to claim 5, wherein the secondary battery is a sulfide-based all-solid-state battery.

7. A backup power supply device according to claim 6, wherein the circuit that indicates a drop in the voltage of the secondary battery is comprised of a light-emitting diode and a drive circuit, and the drive circuit is configured to drive the light-emitting diode intermittently.

8. An electronic device comprising: a motor; an absolute encoder; a secondary battery; a charging circuit for charging the secondary battery; a voltage conversion circuit for converting the voltage of the secondary battery into two different predetermined voltages; and a voltage monitoring circuit for monitoring the input voltage of the voltage conversion circuit, wherein the voltage monitoring circuit switches the voltage of the voltage conversion circuit; the rotating shaft of the motor and the input shaft of the absolute encoder are mechanically connected; and the output side of the voltage conversion circuit is connected to the power supply terminal of the absolute encoder.

9. An electronic device comprising: a motor; an absolute encoder; a secondary battery; a charging circuit for charging the secondary battery; a voltage conversion circuit for converting the voltage of the secondary battery into two different predetermined voltages; and a voltage monitoring circuit for monitoring the input voltage of the voltage conversion circuit, wherein the voltage of the voltage conversion circuit is switched by the voltage monitoring circuit; and further comprising a circuit for indicating a voltage drop of the secondary battery monitored by the voltage conversion circuit; the rotating shaft of the motor and the input shaft of the absolute encoder are mechanically connected; and the output side of the voltage conversion circuit is connected to the power supply terminal of the absolute encoder.

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