JPH10164836A - Device for warning of anomaly in power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inform of failure in a smoothing capacitor included in a switching power supply. SOLUTION: A high-frequency voltage from a switching circuit 22 is rectified through a rectifier circuit 26, smoothed through smoothing capacitors 28, 30 and a smoothing reactor 31, and supplied to reception-related equipment 2 through a voltage adjustment circuit 8. High-frequency noise extracted from the reactor 31 is detected using a level detector 40, and supplied to comparators 42, 44. The comparators 42, 44 are fed with a threshold value corresponding to a high-frequency noise level at which the capacitors 28, 30 should be replaced and a threshold value corresponding to a high-frequency noise level at which attention should be paid to the capacitors 28, 30. When the capacitors 28, 30 are normal as indicated by the output of the comparators 42, 44, a control circuit 58 lights up a pilot lamp 108. If attention should be paid to the capacitors 28, 30, it makes the lamp flash in a long cycle. If the capacitors 28, 20 should be replaced, it makes the lamp flash in a short cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for warning an abnormality in a power supply circuit, and more particularly to a device for warning an abnormality in a power supply circuit having a switching power supply.

[0002]

2. Description of the Related Art As a power supply circuit of an electronic circuit, a circuit having a switching power supply is widely used. this is,
This is because the switching power supply has advantages such as high efficiency, small size, light weight, and low cost. In such a power supply circuit,
After the AC voltage of the commercial AC power supply is rectified by a rectifier circuit on the input side, it is smoothed by a smoothing capacitor and converted to DC. This DC voltage is converted into a high-frequency voltage by a switching circuit. This high-frequency voltage is transformed into a predetermined voltage by a transformer, rectified by a rectifier circuit on the output side, smoothed by a smoothing capacitor, converted to direct current, and supplied to a load. An electrolytic capacitor is used for each smoothing capacitor.

[0003]

Most of the causes of failure of a power supply circuit provided with such a switching power supply are caused by capacity loss of an electrolytic capacitor used as a smoothing capacitor (capacity smaller than a rated capacity). .). Although the reliability of the switching power supply varies depending on use conditions and design conditions, it is considered that it is desirable to replace the electrolytic capacitor in five to seven years. But,
This is a case where specific conditions are assumed, and each power supply circuit is not always arranged in an environment according to these conditions. The life of an electrolytic capacitor is 10 degrees Celsius
It is said that when it rises, it will be about half. It is useless to replace the battery in five years where the use condition is relatively good, and the electrolytic capacitor may fail before the lapse of five years in the place where the use condition is bad. Therefore, it is desirable to monitor whether or not each power supply circuit has a failure.

Some electronic circuits are provided with such a power supply circuit and can be operated by a voltage from another power supply circuit provided outside. In such a case, a power supply circuit that generates a voltage corresponding to the electronic circuit must be connected. However, a power supply circuit that generates an unsupported voltage may be erroneously connected to an electronic circuit. It is desirable to monitor whether such an incorrect power supply circuit is connected.

[0005] A pilot lamp is used in the power supply circuit, but it merely indicates whether the power supply circuit has a voltage capable of lighting the pilot lamp. Therefore, even if the electrolytic capacitor has a capacity loss as described above, or if an erroneous power supply circuit is connected, the lamp is lit without any problem and is not useful for the above-described monitoring.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply abnormality warning device capable of monitoring whether or not a capacity loss of an electrolytic capacitor has occurred in each power supply circuit. Another object of the present invention is to provide a power failure alarm device that monitors whether or not an incorrect power supply circuit is connected.

[0007]

According to the first aspect of the present invention,
It has a DC power supply circuit. The DC power supply circuit includes a switching power supply, rectifying means for rectifying an output voltage of the switching power supply, and a smoothing capacitor for smoothing an output of the rectifying means. Noise detection means detects noise included in the output of the DC power supply circuit. The control unit changes the output state of the notification unit according to the output level of the noise detection unit. In addition, as noise detection means,
Filter means may be provided in the smoothing means including the smoothing capacitor and include a switching frequency of the switching power supply in a pass band.

In a DC power supply circuit provided with a switching power supply, when the smoothing capacitor starts to lose capacity, noise included in the output of the DC power supply circuit, for example, a switching frequency component of the switching power supply increases. And the noise increases as the loss of capacity progresses. Therefore, according to the first aspect of the present invention, noise is detected by the noise detecting means, and the noise is detected according to the output level.
The output state of the notification means is changed to notify the state of the capacity loss of the electrolytic capacitor.

According to a second aspect of the present invention, in the power supply abnormality warning device according to the first aspect, the control means includes a plurality of comparing means for comparing the output of the noise detecting means with different threshold values, and the outputs of these comparing means are provided. And a driving means for changing the output state of the notification means depending on which of the comparison means generates an output.

According to the second aspect of the invention, the state of the output of each comparing means is determined according to the level of the detected noise. That is, if the level of the detected noise exceeds a certain threshold, at least the output of the comparing means to which this threshold is supplied changes. Further, when the level of the detected noise exceeds another threshold, at least the output of the comparing means to which this threshold is supplied changes. In response to such a change in the output of each comparing means, the driving means changes the state of the notifying means, and notifies the detected noise level.

According to a third aspect of the present invention, in the power supply abnormality warning device according to the second aspect, a voltage adjusting means is provided. The voltage adjuster is supplied with the output voltage of the DC power supply circuit on the input side and generates a voltage different from the input voltage on the output side. When at least one of the voltages on the input side and the output side of the voltage adjusting means is out of the allowable range, the voltage determining means changes the state of the output supplied to the driving means.

According to the third aspect of the present invention, if the DC power supply circuit fails due to, for example, complete loss of capacity of the electrolytic capacitor, the voltage on the input side or the output side of the voltage adjusting means becomes out of the allowable range, and The output of the determining means changes. The drive means changes the output state of the notification means according to this change, so that the failure of the DC power supply circuit is determined.

According to a fourth aspect of the present invention, in the power supply abnormality warning device according to the third aspect, a DC voltage is supplied to the voltage adjusting means from a power supply other than the DC power supply circuit.

According to the fourth aspect of the present invention, if the DC voltage from another power supply is not a predetermined value, the voltage on the input side or the output side of the voltage adjusting means is out of the allowable range, and The output of the means changes. The drive means changes the output state of the notification means according to this change,
It turns out that the wrong power supply is connected to the voltage adjusting means.

According to a fifth aspect of the present invention, in the power supply abnormality warning device according to the fourth aspect, the AC noise detecting means for detecting AC noise included in the DC voltage from the another power supply and supplying the AC noise to each of the comparing means. Are provided.

According to the fifth aspect of the present invention, there is a possibility that another power supply will fail. In that case, the AC noise included in the voltage of another power supply increases. Therefore, the AC noise included in the voltage of another power supply is detected and compared with each threshold in each comparing means to determine whether the voltage of another power supply is normal. The result is displayed on the notification means. However,
It is desirable that the AC noise detecting means, including the amplifying means, match the output level of the AC noise detecting means with the level of each threshold.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present embodiment is directed to an electronic circuit, for example, a DC power supply circuit incorporated in a reception-related device such as a booster or a converter used in a joint hearing facility.
The present invention has been implemented.

As shown in FIG. 1, the present embodiment has a load, for example, a reception-related device 2 such as a booster or a converter. This reception-related device 2 includes:
As shown in FIG. 1, a high-frequency signal, for example, a television broadcast signal is supplied to an input terminal 4 via a coaxial cable 3. When the reception-related device 2 is a booster, the input television broadcast signal is amplified and output from the output terminal 6. When the reception-related device 2 is a converter, the input television broadcast signal is frequency-converted,
Output from the output terminal 6.

The operating voltage for the reception-related device 2 is:
It is supplied from the voltage adjustment circuit 8. Voltage adjustment circuit 8
Has a voltage regulator IC 8a and smoothing capacitors 8b and 8c on its input side and output side, respectively.
Then, the voltage adjustment circuit 8 converts the DC voltage supplied to the input side into a voltage having a predetermined value and stabilizes the DC voltage.
Output. For example, if the input voltage is + 15V, this is converted to stabilized + 10V.

The input voltage to the voltage adjustment circuit 8 is supplied from a built-in DC power supply circuit 10 via a diode 12.
In addition, a DC voltage can be supplied to the voltage adjustment circuit 8 from an external power supply provided outside. That is, a coaxial cable 200 is connected to the output terminal 6 as shown in FIG. 6, and a television broadcast signal from the output terminal 6 is transmitted through the coaxial cable 200. This television broadcast signal is supplied to a television receiver (not shown) as a terminal via a power supply device 202. The power supply device 202 may superimpose a DC voltage of, for example, +15 V on the coaxial cable 202. This voltage is obtained, for example, by rectifying and smoothing a commercial AC power supply. When this voltage is superimposed, this DC voltage is extracted by the superimposed voltage extraction circuit 14 connected to the output terminal 6 as shown in FIG. 1 and supplied to the voltage adjustment circuit 8 via the diode 16. The superimposed voltage extraction circuit 14
4a and a capacitor 14b.

In the built-in DC power supply circuit 10, an AC voltage from a commercial AC power supply is transformed by a transformer 17 to a predetermined voltage. The transformed AC voltage is rectified by the rectifier circuit 18, smoothed by the smoothing capacitor 20, and converted into a DC voltage. This DC voltage is supplied to the switching circuit 22, where it is converted into a high-frequency voltage of several tens KHz to several hundred KHz, for example. This high-frequency voltage is transformed by the transformer 24 and the rectifier circuit 26
And the smoothing capacitors 28, 3
0, smoothed by the smoothing reactor 31, and converted into a DC voltage.

This DC voltage is +15 V as described above.
Is supplied to the voltage adjusting circuit 8 via the diode 12, where the voltage is stabilized at +10 V, and
Supplied to The switching circuit 22 includes a control circuit 32
Is controlled by The voltage of the smoothing capacitor 30 is supplied to the control circuit 32, and the switching circuit 2 is controlled so that the voltage becomes a predetermined value, for example, + 15V.
2 is controlled.

A coil 34 is provided so as to be mutually inductively coupled to the smoothing reactor 31. This coil 34
Constitutes a parallel resonance circuit 33 with a capacitor 36, and its resonance frequency and Q are selected so as to constitute a band-pass filter capable of detecting high-frequency noise, for example, a noise component equal to the switching frequency of the switching circuit 22. At a stage where no loss of capacitance occurs in any of the smoothing capacitors 20, 28 and 30, the noise voltage generated in the resonance circuit 33 is smaller than, for example, 140 mVP-P. However, when the capacitance of the smoothing capacitors 20, 28, 30 is reduced to about half, the noise voltage generated in the resonance circuit 33 is about 500 mVP-P. The output voltage of the resonance circuit 33 is amplified by the amplifier 38,
And a plurality of, for example, two comparators 4
2, 44. The resonance circuit 33 and the level detector 40 constitute noise detection means.

A threshold voltage CVL corresponding to, for example, 500 mVP-P is supplied to the comparator 42 by a voltage source 46, and a threshold voltage CVH corresponding to, for example, 800 mVP-P is supplied to the comparator 44 by a voltage source 48. ing.
Note that 800 mVP-P is equivalent to the smoothing capacitors 20, 28,
This is the output voltage of the resonance circuit 33 when it is better to replace 30. However, at 800 mVP-P, the DC power supply circuit 10 is still operating normally.

As shown in the center of FIG. 2A, the comparator 42 outputs the threshold voltage C
When VL is exceeded, the output is changed from low (L) level to high (H).
Change to level. Similarly, the comparator 44 is connected to the detector 4
0 is output from the voltage source 48 as shown in the latter half of FIG.
When the threshold voltage exceeds the threshold voltage CVH, the output is changed from L level to H level. The outputs of the comparators 42 and 44 are
Integrating circuits 50 and 52, Schmitt trigger circuit 5, respectively
4, 56. For example, the input and output of the comparator 42, the output of the integration circuit 50, and the output of the Schmitt trigger circuit 54 are shown in FIGS. Outputs of the Schmitt trigger circuits 54 and 56 are supplied to a driving unit, for example, a control circuit 58.

An AC noise, for example, a ripple contained in the DC voltage extracted from the superimposed voltage extraction circuit 14 is amplified by an amplifier 62 via a DC blocking capacitor 60 and detected by a level detector 64. The output of the detector 64 is supplied to comparators 42 and 44.
Therefore, for example, when the internal DC power supply 10 is stopped and the reception-related device 2 is operated by the external power supply, the level of the AC noise included in the DC voltage from the external power supply is compared with the threshold values CVH and CVL. Is done. In addition,
When the AC noise is slightly large, the output of the detector 64 becomes the threshold C
VL and when there is much AC noise,
The amplification of the amplifier 62 is selected so that the output of the detector 64 is equal to the threshold value CVH.

The input side voltage of the voltage adjusting circuit 8 is
6, 68. In the comparator 66, the allowable upper limit voltage of the input side voltage is set by the voltage source 70, and when the input side voltage becomes larger than the allowable upper limit voltage, the comparator 66 sets the output to the H level. In the comparator 68, the allowable lower limit voltage of the input side voltage is set by the voltage source 72. When the input side voltage becomes lower than the allowable lower limit voltage, the comparator 68 sets the output to the H level. For example, if the standard value of the input side voltage is +1
If it is 5V, the allowable upper and lower limit voltage is set to 15 ± 1V.

The outputs of the comparators 66 and 68 are supplied to an OR gate 74. Therefore, when the input side voltage deviates from the allowable range defined by the allowable upper and lower limit voltages,
One of the outputs of the comparators 66 and 68 becomes H level,
The output of the OR gate 74 also goes high.

Similarly, the output side voltage of the voltage adjusting circuit 8 is also supplied to the comparators 76 and 78. As shown in FIG. 2B, an allowable upper limit voltage of the output side voltage is set in the comparator 76 by the voltage source 80, and when the output side voltage becomes larger than the allowable upper limit voltage, the comparator 76 outputs the output. Is set to the H level. The allowable lower limit voltage of the output side voltage is set in the comparator 78 by the voltage source 82, and when the output side voltage becomes lower than the allowable lower limit voltage, the comparator 78 sets the output to the H level. For example, if the standard value of the output side voltage is + 10V, the allowable upper and lower limit voltage is set to 10 ± 0.5V.

The outputs of the comparators 76 and 78 are output from an OR gate 84.
Is supplied to Therefore, when the output voltage deviates from the allowable range defined by the allowable upper and lower limit voltages, one of the outputs of the comparators 76 and 78 becomes H level, and the output of the OR gate 84 also becomes H level.

The outputs of the OR gates 74 and 84 are supplied to a NOR gate 86. The output of the NOR gate 86 is at H level when both inputs are at L level, but the output is at L level except when both inputs are at the above level. Therefore, when at least one of the voltage on the input side and the output side of the voltage adjustment circuit 8 is out of the allowable range, the output of the NOR gate 86 becomes L level, and the voltage on both the input side and the output side of the voltage adjustment circuit 8 is allowable. When it is within the range, the output of the NOR gate 86 becomes H level. The output of the NOR gate 86 is supplied to the control circuit 58.

The reason why at least one of the voltages on the input side and the output side of the voltage adjusting circuit 8 is out of the allowable range is when at least one of the smoothing capacitors 20, 28, 30 completely loses capacity. , When the voltage supplied from outside is a voltage other than + 15V. If the voltage adjustment circuit 8 itself fails, the voltage on the output side falls outside the allowable range.

As shown in FIG. 4, the control circuit 58 controls the inverter 8 for inverting the output of the NOR gate 86.
Eight. Therefore, when at least one of the voltage on the input side and the output side of the voltage adjustment circuit 8 is out of the allowable range, the output of the inverter 88 becomes H level.

The AND gate 90 includes a NOR gate 86
And the output of the Schmitt trigger 56 are supplied. When the output of the resonance circuit 33 is larger than the threshold value CVH, that is, when the level of the high-frequency noise included in the output voltage of the internal DC power supply circuit 10 changes the smoothing capacitors 18, 28, 30. When the level becomes better, the output is set to the H level. Therefore, the voltages on the input side and the output side of the voltage adjustment circuit 8 are both within the allowable range, and the smoothing capacitors 18, 28,
When it is better to replace 30, the output of the AND gate 90 is set to the H level.

The AND gate 92 includes a NOR gate 86
And the output of the Schmitt trigger 54 are supplied. The Schmitt trigger 54 sets the output to the H level when the output of the resonance circuit 33 is larger than the threshold value CVL, that is, when the capacitance of the smoothing capacitors 18, 28, and 30 becomes less than half of the rating. Therefore, the voltage adjustment circuit 8
Both the input side and output side voltage are within the allowable range,
When it is necessary to pay attention to the smoothing capacitors 18, 28, and 30, the AND gate 92 sets the output to the H level.

However, the AND gate 92 keeps the output high even when the Schmitt trigger 56 sets the output high.
Level. Therefore, the output of the AND gate 90 inverted by the inverter 94 and the output of the AND gate 92 are supplied to the AND gate 96. Therefore, A
The ND gate 96 determines that the voltage on the input side and the output side of the voltage adjustment circuit 8 are both within the allowable range and that the smoothing capacitor 1
It is not necessary to replace 8, 28, 30. However, only when it is necessary to pay attention to the smoothing capacitors 20, 28, 30
The output is set to H level.

The AND gate 98 includes a NOR gate 86
, The output of the inverter 94, and the AND gate 92
Is inverted by the inverter 100. Therefore, the output of the AND gate 98 is set to the H level only when the voltages on the input side and the output side of the voltage adjustment circuit 8 are both within the allowable range and no attention is required for the smoothing capacitors 20, 28, and 30. .

As described above, the outputs of the inverter 88 and the AND gates 90, 96, 98 are not simultaneously at the H level.

Inverter 88, AND gates 90, 9
The outputs of 6 and 98 are supplied to one-shot multivibrators provided in the one-shot multi section 102 shown in FIG. 1 in correspondence with AND gates 90, 96 and 98, respectively. The outputs of these one-shot multivibrators are supplied to reset-type latch circuits provided in the reset-type latch circuit unit 104 in correspondence with these one-shot multivibrators.

The outputs of these reset type latch circuits are supplied to a variable blinking circuit 106. Variable blinking circuit 106
Is constituted by a notifying means, for example, an astable multivibrator having a load on the pilot lamp 108, and its time constant is changed by the output of each reset type latch circuit.

When the output of the inverter 88 is at the H level,
The output of the reset type latch circuit corresponding to the inverter 88 causes the pilot lamp 108 to blink at a very short cycle as shown in FIG. This notifies that the built-in DC power supply circuit 10 is unusable, that an incorrect external power supply is connected, or that the voltage adjustment circuit 8 is faulty.

When the output of the AND gate 90 is at the H level, the output of the reset type latch circuit corresponding to the AND gate 90 causes the period longer than that of FIG. 5D as shown in FIG. Causes the pilot lamp 108 to blink. Thereby, the smoothing capacitors 20, 28, 3
Notify that 0 needs to be replaced.

When the output of the AND gate 96 is at the H level, the output of the reset type latch circuit corresponding to the AND gate 96 causes the output of the reset type latch circuit as shown in FIG.
The pilot lamp 108 blinks in a longer cycle than in (c). Thereby, the smoothing capacitors 20, 28, 30
Is about half of the rated capacity and alerts you that caution is required.

When the output of AND gate 98 is at H level, the output of reset type latch circuit corresponding to AND gate 98 keeps pilot lamp 108 lit. Thereby, the smoothing capacitor 2
At 0, 28, and 30 there is no loss of capacity, and it is notified that the external power supply is not erroneously connected.

The resonance circuit 33, the level detector 40, the comparators 42 and 44, the control circuit 58, the comparators 66, 68, 76,
78 and the like constitute control means.

In the above embodiment, the coil 34 mutually inductively coupled to the smoothing reactor 31 and the capacitor 36 constituting the resonance circuit 33 are used as a part of the noise detecting means. However, a filter having a pass band of the frequency of the noise may be provided on the output side of the built-in DC power supply circuit 10 to detect the noise component.

Since the high frequency noise is extracted from the middle of the smoothing means by using the coil 34, there are the following advantages. The high-frequency noise generated by the switching of the switching circuit 22 also flows to the reception-related device 2 that is a load. However, since the high-frequency noise is extracted from the smoothing means, the high-frequency noise does not flow to the reception-related device 2 side, and thus malfunction of the reception-related device 2 due to the high-frequency noise can be prevented. Further, since a band-pass filter is formed by the coil 34 and the capacitor 36, high-frequency noise can be taken out well. Further, for example, the ground portion of the frame in which the built-in DC power supply circuit 10 and the reception-related device 2 are provided is
If not well connected to ground, high frequency noise will increase. Therefore, in the inspection at the time of shipping this product, for example, if the pilot lamp is blinking, it can be understood that the ground portion is not satisfactorily connected to the ground.

In the above embodiment, the power supply state is notified by changing the blinking cycle of the pilot lamp in four steps, but the present invention is not limited to four steps. For example, the progress of the loss of capacity of the smoothing capacitor can be notified in detail by changing the blinking cycle in more steps. In the above embodiment, the pilot lamp 1
The status of the power supply is notified by 08, but the present invention is not limited to this. For example, the notification can be made by voice. Alternatively, the inverter 8 of the control circuit 58 shown in FIG.
8. Transfer the output state of the AND gates 90, 96, 98 to the head end side of the joint hearing facility, using, for example, a status monitor provided in the reception-related device 2;
The state of the power supply may be displayed on a monitor screen on the head end side.

In the above-described embodiment, the present invention is applied to the power supply of the reception related equipment such as the booster and the converter. However, the present invention can be applied to the power supply of other electronic circuits. .

[0050]

As described above, according to the first aspect of the present invention, noise is detected by the noise detecting means, and the output state of the notifying means is changed in accordance with the output level of the noise. Notifying the state. Therefore,
In a switching power supply, it is possible to prevent an electronic circuit from suddenly becoming unusable due to sudden loss of capacity of a smoothing capacitor attached thereto.

According to the second aspect of the present invention, the driving means changes the state of the notifying means in accordance with the change of the output of each comparing means, and determines the level of the detected noise. It is possible to know the condition of the smoothing capacitor, such as whether the smoothing capacitor needs to be replaced, and whether it is sufficient to simply pay attention to the state of the smoothing capacitor.

According to the third aspect of the present invention, it is possible to notify that the capacity loss has occurred completely from the state of the DC voltage.
The failure state of the DC power supply can be grasped.

According to the present invention, in addition to being able to know the condition of the smoothing capacitor of the internal DC power supply circuit, when an external power supply is used, whether the wrong external power supply is used is determined. You can also know whether or not.

According to the fifth aspect of the invention, it is determined whether or not the voltage of the external power supply is normal based on the AC noise included in the external power supply, and whether or not the external power supply has failed is determined. Can be determined.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a power supply circuit implementing a power supply abnormality warning device according to the present invention.

FIG. 2 is a waveform diagram showing an output of a level detection circuit 40 and a waveform diagram of input and output voltages of a voltage adjustment circuit 8 in the embodiment.

FIG. 3 shows an input / output voltage of a comparator 42, an output voltage of an integration circuit 50, and a Schmitt trigger circuit 5 in the embodiment.
FIG. 4 is a diagram showing an output voltage of FIG.

FIG. 4 is a block diagram of a control circuit 58 according to the embodiment.

FIG. 5 is a diagram showing an operation state of a pilot lamp in the embodiment.

FIG. 6 is a block diagram showing a connection state of the embodiment.

[Explanation of symbols]

 Reference Signs List 8 voltage adjustment circuit (voltage adjustment means) 10 DC power supply circuit 22 switching circuit (switching power supply) 24 transformer 26 rectification circuit 28, 30 smoothing circuit 33 resonance circuit (high-frequency noise detection means) 40 level detection circuit (high-frequency noise detection means) 42 44 Comparator 58 Control circuit (drive means) 66 68 76 78 Comparator (voltage determination means) 108 Pilot lamp (notification means)

Claims (5)

[Claims] 1. A DC power supply circuit comprising: a switching power supply; rectifying means for rectifying an output voltage of the switching power supply; a smoothing capacitor for smoothing an output of the rectifying means; and noise included in an output of the DC power supply circuit. A power supply abnormality warning device comprising: a noise detection unit that detects a state of the power supply; a notification unit; and a control unit that changes an output state of the notification unit according to an output level of the noise detection unit. 2. The power supply abnormality warning device according to claim 1, wherein said control means is provided with a plurality of comparison means for comparing the output of said noise detection means with different threshold values, respectively, and outputs of said comparison means are inputted. And a driving unit that changes the output state of the notification unit depending on whether an output is generated from the comparison unit. 3. The power supply abnormality warning device according to claim 2, wherein an output voltage of the DC power supply circuit is supplied to an input side and a voltage different from the input voltage is generated on an output side. A power supply abnormality warning device comprising: a determination unit configured to change a state of an output supplied to the driving unit when at least one of voltages on an input side and an output side of the adjustment unit is out of an allowable range. 4. The power supply abnormality warning device according to claim 3, wherein the voltage adjusting means is supplied with a DC voltage from a power supply other than the DC power supply circuit. 5. The power supply abnormality warning device according to claim 4, further comprising an AC noise detection unit that detects AC noise included in the DC voltage from the another power supply and supplies the AC noise to each of the comparison units. Power failure warning device.