JP2016059098A - Power supply device, television device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a short circuit failure of a diode or a choke coil, in a power supply device having a switching element, with a simple configuration.SOLUTION: A power supply device 1 includes a rectifier circuit 11 for rectifying an AC voltage, a choke coil 12 connected to the rectifier circuit 11, a diode 13 connected to the choke coil 12, a capacitor 14 for charging a current rectified by the rectifier circuit 11 through the choke coil 12 and the diode 13, and a switching element 15, connected in parallel to a series connection circuit of the capacitor 14 and the diode 13, for on/off control of a current flowing to the capacitor 14 through the diode 13. The power supply device 1 further includes a determination part 17a for detecting conduction time of the switching element 15, and determining a short circuit of the diode 13 or the choke coil 12, based on the conduction time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device, a television device, and an electronic device, and more particularly to a power supply device having a switching element, a television device including the power supply device, and an electronic device including the power supply device.

  2. Description of the Related Art Conventionally, a step-up switching power supply device having a switching element has been used as a power supply device for electronic equipment such as a television device. This switching power supply device is provided with a diode in addition to the switching element, but when the diode is short-circuited, the operation of the circuit in the power supply device does not stop, resulting in heat generation and destruction of the switching element. There is a possibility.

  As a countermeasure, for example, Patent Document 1 discloses that a booster circuit having a low current source for lighting an LED (Light Emitting Diode) includes a detection circuit that detects a voltage value of an output low current source, thereby short-circuiting a diode. A technique for detecting a failure is disclosed.

  Regarding the failure of the booster circuit, Patent Document 2 discloses a technique for detecting the terminal voltage of the switching element to detect and stop the fixing failure of the switching element. Patent Document 3 discloses a power supply device including a power factor correction circuit.

JP 2009-290937 A JP 2011-193549 A JP 2007-74813 A

  However, in the technique described in Patent Document 1, it is necessary to additionally provide a detection circuit for detecting a short circuit failure of the diode. Further, the technique described in Patent Document 2 is not intended to detect a short-circuit failure of a diode. Note that the technique described in Patent Document 3 is not intended to detect a failure.

  Furthermore, although the power supply device including the switching element as described above includes not only a diode but also a choke coil, the techniques described in Patent Documents 1 and 2 cannot detect a short-circuit failure of the choke coil.

  The present invention has been made in view of the above-described actual situation, and an object of the present invention is to detect a short-circuit failure of a diode or a choke coil with a simple configuration in a power supply device including a switching element, and so on. It is an object to provide a television set and an electronic device provided with a power supply device.

  In order to solve the above problems, a first technical means of the present invention includes a rectifier circuit that rectifies an alternating voltage, a choke coil connected to the rectifier circuit, a diode connected to the choke coil, A capacitor for charging the current rectified by the rectifier circuit via the choke coil and the diode, and a series connection circuit of the capacitor and the diode are connected in parallel to the capacitor via the diode. And a switching device for controlling on / off of current, wherein the determination unit detects a conduction time of the switching element and determines a short circuit of the diode or the choke coil based on the conduction time Is further provided.

  According to a second technical means of the present invention, in the first technical means, the determination unit compares the conduction time with a predetermined threshold value, and when the conduction time falls below the predetermined threshold value, It is determined that the choke coil is short-circuited.

  According to a third technical means of the present invention, in the first technical means, the determination unit compares the conduction time with a predetermined threshold value, and the conduction time falls below the predetermined threshold value for a predetermined number of times. In addition, it is determined that the diode or the choke coil is short-circuited.

  A fourth technical means of the present invention is characterized in that, in any one of the first to third technical means, the switching element is turned off when it is determined that the determination unit has short-circuited. is there.

  According to a fifth technical means of the present invention, in any one of the first to fourth technical means, a switch for cutting off the AC voltage to the rectifier circuit when it is determined that the determination unit has short-circuited, It is characterized by having provided.

  According to a sixth technical means of the present invention, in any one of the first to fifth technical means, the current to the load circuit connected to the power supply device is interrupted when it is determined that the determination unit has short-circuited. The switch is further provided with a switch.

A seventh technical means of the present invention is a television apparatus provided with the power supply device according to any one of the first to sixth technical means.
An eighth technical means of the present invention is an electronic device including the power supply device according to any one of the first to sixth technical means.

  According to the present invention, in a power supply device including a switching element, it is possible to detect a short-circuit failure of a diode or a choke coil with a simple configuration. In addition, according to the present invention, it is possible to provide a television apparatus or an electronic device including such a power supply device.

It is a circuit diagram showing an example of 1 composition of a power unit concerning a 1st embodiment of the present invention. It is a figure which shows the example of the voltage waveform in the normal time concerning the choke coil in the power supply device of FIG. It is a figure which shows the example of the current waveform in the normal time which flows into the switching element in the power supply device of FIG. It is a figure which shows the example of the control voltage waveform at the time of the normal with respect to the switching element in the power supply device of FIG. It is a figure which shows the example of the voltage waveform at the time of abnormality concerning a choke coil in the power supply device of FIG. It is a figure which shows the example of the electric current waveform at the time of abnormality which flows into the switching element in the power supply device of FIG. It is a figure which shows the example of the control voltage waveform at the time of abnormality with respect to the switching element in the power supply device of FIG. It is a circuit diagram which shows the other structural example of the power supply device which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows the other structural example of the power supply device which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows one structural example of the power supply device which concerns on 2nd Embodiment relevant to this invention. It is a figure which shows the example of the current waveform at the time of normal flowing into the switching element in the power supply device of FIG. It is a figure which shows the example of the current waveform at the time of abnormality which flows into the switching element in the power supply device of FIG.

  Hereinafter, various embodiments of a power supply device according to the present invention will be described with reference to the drawings. This power supply device is characterized in that a short circuit of a provided diode or choke coil is determined, and can be incorporated into various electronic devices such as a television device and a recorder device.

(First embodiment)
A power supply device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3C. FIG. 1 is a circuit diagram showing a configuration example of a power supply device according to the first embodiment of the present invention.

  As shown in FIG. 1, the power supply device 1 according to the present embodiment includes a rectifier circuit 11, a choke coil 12, a diode 13, a capacitor 14, a switching element 15, and a microcomputer (microcomputer) 17. Device for supplying power. The microcomputer 17 is an example of a control unit that controls the power supply device 1 and includes an IC (Integrated Circuit).

  The rectifier circuit 11 is a circuit that is connected to the AC power source 10 and rectifies an AC voltage. As AC power supply 10, commercial power supplies, such as 100V, are mentioned, for example. Moreover, as a full wave rectification diode, the bridge type thing which performs full wave rectification by a diode bridge is mentioned, for example.

  The choke coil 12 is a boost choke coil connected to the rectifier circuit 11. Further, the auxiliary coil 18 is differentially electromagnetically coupled to the choke coil 12 and a diode 13 is connected thereto. The auxiliary coil 18 is for detecting the current flowing through the choke coil 12.

  The capacitor 14 is a capacitor for charging the current rectified by the rectifier circuit 11 via the choke coil 12 and the diode 13. Both ends of the capacitor 14 correspond to output terminals of the power supply device 1, and a load circuit 20 serving as a load of the power supply device 1 is connected to supply power to the load circuit 20.

  The switching element 15 is connected in parallel to a series connection circuit of the capacitor 14 and the diode 13, and is an element for controlling on / off of a current to the capacitor 14 via the diode 13. As shown in the figure, the switching element 15 includes, for example, a field effect transistor (FET), but is not limited thereto, and may be an insulated gate bipolar transistor (IGBT) or the like. In addition, a resistor 16 is connected in series between the switching element 15 and the negative electrode side of the rectifier circuit 11.

  When the switching element 15 is turned on, a path of the choke coil 12, the switching element 15, and the resistor 16 is generated, and a current flows through the choke coil 12 to store energy. On the other hand, when the switching element 15 is turned off, a path of the choke coil 12, the diode 13, and the capacitor 14 is generated, and the current flowing through the choke coil 12 does not suddenly become zero. Current is injected. That is, when the switching element 15 is turned off, the energy stored in the choke coil 12 is released to the capacitor 14 via the diode 13 and the capacitor 14 is charged. For this reason, the capacitor 14 is charged with a voltage higher than the voltage supplied by the AC power supply 10.

  Due to the release of energy from the choke coil 12, as time passes, the current flowing through the choke coil 12 decreases and approaches zero. The current change of the choke coil 12 can be detected as a secondary voltage induced in the auxiliary coil 18. In this example, the microcomputer 17 detects that the current of the choke coil 12 has become zero by detecting the secondary voltage of the auxiliary coil 18.

  When the microcomputer 17 detects that the current of the choke coil 12 has become zero, the capacitor 14 cannot be charged any more, and thus controls the switching element 15 to be turned on. Further, when the predetermined minimum off time has not elapsed, the microcomputer 17 may perform control so that the switching element 15 is not turned on even when the current of the choke coil 12 becomes zero.

  The microcomputer 17 obtains the output instantaneous voltage Vin from the rectifier circuit 11 and changes the peak current value Ipk which is a threshold according to the output instantaneous voltage, and a current exceeding the threshold flows to the switching element 15. In such a case, the switching element 15 is controlled to be turned off. Here, the current flowing through the switching element 15 can be measured by the microcomputer 17 obtaining the voltage of the resistor 16.

  In this way, the on-time (conduction time) from the time when the switching element 15 is turned on to the time when it is turned off is determined. The on-time Ton can be defined by L × Ipk / Vin. Here, when the self-inductance of the choke coil 12 is L1, L = L1. Vin is an instantaneous output voltage from the rectifier circuit 11. Further, the microcomputer 17 is configured so as to detect the voltage across the capacitor 14, and the microcomputer 17 compares this voltage with a threshold value and uses the comparison result for on-control and / or off-control of the switching element 15. May be.

  Thus, the microcomputer 17 determines the on-time (conduction time) and off-time of the switching element 15 based on the instantaneous output voltage of the rectifier circuit 11 and the current flowing through the switching element 15 (voltage of the resistor 16). By controlling the switching element 15 in accordance with the determination, the input current approaches a sine wave shape.

  As described above, it can be said that the power supply device 1 is equipped with a power factor correction (PFC) circuit that prevents the input current from becoming a pulse shape and causing the power factor to deteriorate. Note that the control unit exemplified by the microcomputer 17 only needs to be able to perform PFC control. Instead, for example, an analog circuit as described in Patent Document 3 may be added, or all may be configured with an analog circuit.

  In addition to such a configuration, the power supply device 1 according to the present embodiment detects a conduction time of the switching element 15 and determines a short circuit (short) of the diode 13 or the choke coil 12 based on the conduction time. Is provided. The determination unit 17a can detect not only when the choke coil 12 is short-circuited but also when the auxiliary coil 18 is short-circuited.

  The determination unit 17a can be incorporated into the microcomputer 17 as illustrated, but is not limited thereto, and may be provided in the power supply device 1. When the determination unit 17a is incorporated in the microcomputer 17, it can also be incorporated as firmware.

  The normal operation and abnormal operation of the power supply apparatus 1 will be described with reference to FIGS. 2A to 2C and FIGS. 3A to 3C, respectively. 2A is a diagram illustrating an example of a normal voltage waveform applied to the choke coil in the power supply device of FIG. 1, and FIG. 2B is a diagram illustrating an example of a normal current waveform flowing into the switching element in the power supply device of FIG. 2C is a diagram illustrating an example of a control voltage waveform in a normal state with respect to the switching element in the power supply device of FIG. 1. 3A is a diagram showing an example of an abnormal voltage waveform applied to the choke coil in the power supply device of FIG. 1, and FIG. 3B is a diagram showing an example of an abnormal current waveform flowing into the switching element in the power supply device of FIG. 3C is a diagram illustrating an example of a control voltage waveform when the switching element in the power supply device of FIG. 1 is abnormal.

  The voltage Vin as illustrated in FIG. 2A is input from the rectifier circuit 11 to the choke coil 12. Under normal conditions, the current Id flowing into the switching element 15 with respect to the voltage Vin is as shown in FIG. 2B. As a result, the control voltage Vg from the microcomputer 17 to the switching element 15 is as shown in FIG. 2C.

  The conduction time (on time) of the switching element 15 by the normal control voltage Vg is Ton = L × Ipk / Vin. Note that not only FIG. 2C but also FIG. 2B shows the time corresponding to this Ton. As described above, the peak current value Ipk is a value that changes as shown in FIG. 2B in the PFC circuit, and is controlled by the microcomputer 17 so as to change according to the instantaneous output voltage from the rectifier circuit 11.

  At the time of abnormality (at the time of short circuit), the current Id flowing into the switching element 15 is as shown in FIG. 3B with respect to the voltage Vin illustrated in FIG. 3A (same as the voltage Vin in FIG. 2A). As a result, the control voltage Vg from the microcomputer 17 to the switching element 15 is as shown in FIG. 3C.

  Specifically, first, when the diode 13 is short-circuited, the current Id is increased by the current from the capacitor 14, and when the auxiliary coil 18 or the choke coil 12 is short-circuited, L = 0. Therefore, at any moment when the switching element 15 is turned on, a large current flows as the current Id and instantaneously exceeds the peak current value Ipk. Therefore, the microcomputer 17 instantaneously turns off the switching element 15. Become. That is, the ON time of the switching element 15 by the control voltage Vg at the time of abnormality becomes Ton <L × Ipk / Vin, and actually becomes very short as shown in FIG. 3C. Note that not only FIG. 3C but also FIG. 3B illustrates the time corresponding to this Ton.

  As described above, the on-time (conduction time) Ton is shortened at the time of abnormality unlike the normal time. Therefore, in the present embodiment, the determination unit 17a compares the conduction time with a predetermined threshold (L × Ipk / Vin or a value smaller than that with a margin, for example, a value that is ½ times), It may be determined that any one of the diode 13, the choke coil 12, and the auxiliary coil 18 is short-circuited when the value is below the threshold.

  As described above, in this embodiment, since the short-circuit is detected by monitoring the ON time (conduction time) of the switching element, that is, the ON-Duty, a short-circuit failure of the diode or the choke coil is detected with a simple configuration. Will be able to.

  In addition, the determination unit 17a compares the conduction time with a predetermined threshold value, and when the conduction time falls below the predetermined threshold value for a predetermined number of times, any one of the diode 13, the choke coil 12, and the auxiliary coil 18 is used. May be determined to be short-circuited. Thereby, it becomes possible to determine a short circuit more reliably. Note that the predetermined number of times may be determined to a value of 2 or more as appropriate.

  In addition, the power supply device 1 preferably turns off the switching element 15 when it is determined by the determination unit 17a that it is short-circuited, that is, stops subsequent on / off control. Therefore, it is preferable that the power supply device 1 further includes a stop instructing unit that gives such an off instruction. This stop instruction unit may be provided in the microcomputer 17. Thereby, the operation of the switching element 15 can be stopped while the switching element 15 is turned off at the time of a short circuit, and the PFC control can be stopped.

  FIG. 4 is a circuit diagram showing another configuration example of the power supply device according to the present embodiment. The power supply device 1a in this configuration example shown in FIG. 4 is the power supply device 1 further including a switch 10a. The switch 10 a is a switch that cuts off the AC voltage to the rectifier circuit 11 when it is determined that the determination unit 17 a has short-circuited, and may be cut off by control from the microcomputer 17. Thereby, the electric current to the rectifier circuit 11 can be interrupted at the time of a short circuit. Further, the switch 10a may be provided together with the stop instruction unit.

  FIG. 5 is a circuit diagram showing another configuration example of the power supply device according to the present embodiment. The power supply device 1b in this configuration example shown in FIG. 5 is the power supply device 1 further including a switch 20a. The switch 20a is a switch that cuts off the current to the load circuit 20 connected to the power supply device 1b when it is determined that the determination unit 17a has short-circuited. Thereby, the electric current to the load circuit 20 can be interrupted at the time of a short circuit. Further, the switch 20a may be provided together with the switch 10a, or the stop instruction unit may be provided together.

  Next, a television apparatus and other electronic devices provided with the power supply devices 1, 1a, 1b as described above will be briefly described. Here, a configuration example of a television device will be described. The television apparatus includes a display unit, a speaker unit, a tuner unit, and the like, and displays a video indicated by the video signal on the display unit among broadcast signals received by the tuner unit, and outputs audio indicated by the audio signal from the speaker unit. It is configured as follows. Note that when the display unit includes a non-self-luminous display panel such as a liquid crystal panel, the display unit also includes a backlight device. The television apparatus includes the power supply devices 1, 1 a, 1 b and the like shown in FIG. 1 described above, and the load circuit 20 is connected to parts such as a display unit, a speaker unit, and a tuner unit that require power supply.

(Second Embodiment)
The short-circuit fault detection method according to the first embodiment described above can be applied to a DC power supply apparatus that does not require the rectifier circuit 11. Such a power supply device will be described as a second embodiment. FIG. 6 is a circuit diagram showing a configuration example of the power supply device according to the second embodiment related to the present invention.

  The power supply device 6 according to the present embodiment is a booster circuit (step-up switching power supply device) that does not include a PFC, includes a DC power supply 61, a choke coil 62, a diode 63, a capacitor 64, a switching element 65, a resistor 66, a microcomputer 67 having a determination unit 67a, and an auxiliary coil 68.

  The diode 63, the capacitor 64, the switching element 65, the resistor 66, and the auxiliary coil 68 correspond to the diode 13, the capacitor 14, the switching element 15, the resistor 16, and the auxiliary coil 18 in the power supply device 1, respectively. Detailed description thereof is omitted. The load circuit 70 corresponds to the load circuit 20 of FIG.

  The choke coil 62 is basically the same as the choke coil 12 in the power supply device 1 of FIG. 1 except that it is connected to the DC power supply 61, and a detailed description thereof will be omitted. Further, the microcomputer 67 does not perform PFC control as compared with the microcomputer 17 of the power supply device 1, and the control content is different in that the peak current value Ipk is constant.

  The microcomputer 67 may turn on the switching element 65 when the output voltage of the auxiliary coil 68 is detected and becomes zero as in the first embodiment, but is not limited thereto. For example, the microcomputer 67 may determine the control timing of the switching element 65 by an arbitrary method such as turning on the switching element 65 at regular intervals. In that case, the power supply device 6 does not need to be provided with the auxiliary coil 68. Further, the microcomputer 67 may be configured to be able to detect the voltage at both ends of the capacitor 64, and may be used for on control and / or off control of the switching element 65 by comparing this voltage with a threshold value.

  The power supply device 6 according to the present embodiment includes the determination unit 67a as a main feature thereof. The determination unit 67a detects the conduction time of the switching element 65, as in the determination unit 17a, and a diode based on the conduction time. 63, a short circuit of one of the choke coil 62 and the auxiliary coil 68 is determined.

  The normal operation and abnormal operation of the power supply device 6 will be described with reference to FIGS. 7A and 7B, respectively. 7A is a diagram illustrating an example of a current waveform in a normal state that flows into the switching element in the power supply device of FIG. 6, and FIG. 7B is a diagram illustrating an example of a current waveform in an abnormal state that flows into the switching element in the power supply device in FIG. It is.

  A DC voltage is input from the DC power supply 61 to the choke coil 62, and a current Id flowing into the switching element 65 with respect to this voltage is as shown in FIG. The normal conduction time (on time) of the switching element 65 is Ton = L × Ipk / Vin. This Ton is a time corresponding to Ton shown in FIG. 7A. In this embodiment, since no PFC circuit is provided, Ipk is a constant peak current value, which corresponds to the height of the waveform in FIGS. 7A and 7B. In the present embodiment, L is the self-inductance L1 of the choke coil 62 when the auxiliary coil 68 is not provided.

  On the other hand, the current Id flowing into the switching element 65 at the time of abnormality (during a short circuit) is as shown in FIG. 7B. The conduction time of the switching element 65 at the time of abnormality is Ton <L × Ipk / Vin as shown in FIG. 7B corresponding time Ton.

  As described above, the on-time (conduction time) Ton is shortened at the time of abnormality unlike the normal time. Therefore, also in the present embodiment, the determination unit 67a compares the conduction time with a predetermined threshold value (L × Ipk / Vin or a value smaller than that with a margin, for example, a value that is ½ times). It may be determined that any one of the diode 63, the choke coil 62, and the auxiliary coil 68 is short-circuited when the value is below the threshold.

  As described above, in the present embodiment, since the short time is determined by detecting the ON time (conduction time) of the switching element, it is possible to detect a short circuit failure of the diode or the choke coil with a simple configuration. Become.

  Also in this embodiment, the determination unit 67a compares the conduction time with a predetermined threshold value, and when the conduction time falls below the predetermined threshold value for a predetermined number of times, the diode 63, the choke coil 62, and the auxiliary It may be determined that any one of the coils 68 is short-circuited.

  As described above, also in this embodiment, it is possible to detect a short-circuit failure of a diode or a choke coil with a simple configuration. Also in the present embodiment, the stop instructing unit and the voltage cut-off switch as described in the first embodiment (however, in the first embodiment, the switch is for AC voltage cut-off in the first embodiment) Any one or a plurality of switches for cutting off a load circuit) can be applied. Further, the power supply device according to the present embodiment can also be mounted on a television set or other electronic devices, as in the first embodiment.

(About the first and second embodiments)
As described above, the power supply device according to the first embodiment of the present invention includes a rectifier circuit that rectifies an AC voltage, a choke coil connected to the rectifier circuit, a diode connected to the choke coil, A capacitor for charging the current rectified by the rectifier circuit via the choke coil and the diode, and a series connection circuit of the capacitor and the diode are connected in parallel to the capacitor via the diode. And a switching device for controlling on / off of the current of the power supply device, wherein a determination is made to detect a short time of the diode or the choke coil based on the conduction time by detecting a conduction time of the switching device. It is characterized by further comprising a section. Thereby, it becomes possible to detect a short-circuit failure of the diode or the choke coil with a simple configuration.

  The determination unit preferably compares the conduction time with a predetermined threshold value, and determines that the diode or the choke coil is short-circuited when the conduction time is below the predetermined threshold value. Thereby, a short circuit can be reliably determined.

  The determination unit compares the conduction time with a predetermined threshold value, and determines that the diode or the choke coil is short-circuited when the conduction time is continuously lower than the predetermined threshold value a predetermined number of times. Is preferred. Thereby, it becomes possible to determine a short circuit more reliably.

  Moreover, it is preferable that the power supply device according to the first embodiment turns off the switching element when it is determined that the determination unit has short-circuited. Thereby, operation | movement of a switching element can be stopped at the time of a short circuit.

  Moreover, it is preferable that the power supply device according to the first embodiment further includes a switch that cuts off the AC voltage to the rectifier circuit when it is determined that the determination unit has short-circuited. Thereby, the electric current to a rectifier circuit can be interrupted at the time of a short circuit.

  Moreover, it is preferable that the power supply device according to the first embodiment further includes a switch that cuts off a current to a load circuit connected to the power supply device when it is determined by the determination unit that a short circuit has occurred. Thereby, the electric current to a load circuit can be interrupted at the time of a short circuit.

Further, the short-circuit fault detection method in the first embodiment can also be applied to a DC power supply apparatus as described in the second embodiment.
A power supply apparatus according to a second embodiment related to the present invention includes a choke coil connected to a DC power supply, a diode connected to the choke coil, a current from the DC power supply, the choke coil and the diode. And a switching element connected in parallel to a series connection circuit of the capacitor and the diode, and for controlling on / off of the current to the capacitor via the diode. The power supply device further includes a determination unit that detects a conduction time of the switching element and determines a short circuit of the diode or the choke coil based on the conduction time. Thereby, it becomes possible to detect a short-circuit failure of the diode or the choke coil with a simple configuration.

  In addition, it is possible to provide a television apparatus and an electronic device including the power supply device according to various embodiments as described above.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 6 ... Power supply device, 10 ... AC power supply, 10a ... Switch, 11 ... Rectifier circuit, 12, 62 ... Choke coil, 13, 63 ... Diode, 14, 64 ... Capacitor, 15, 65 ... Switching element , 16, 66, resistors, 67, microcomputer, 17a, 67a, determination unit, 18, 68, auxiliary coil, 20, 70, load circuit, 20a, switch, 61, DC power supply.

Claims (8)

A rectifier circuit that rectifies an AC voltage, a choke coil connected to the rectifier circuit, a diode connected to the choke coil, and a current rectified by the rectifier circuit is charged via the choke coil and the diode. And a switching element that is connected in parallel to a series connection circuit of the capacitor and the diode and that controls on / off of the current to the capacitor via the diode. There,
The power supply apparatus further comprising a determination unit that detects a conduction time of the switching element and determines a short circuit of the diode or the choke coil based on the conduction time.   The determination unit compares the conduction time with a predetermined threshold value, and determines that the diode or the choke coil is short-circuited when the conduction time falls below the predetermined threshold value. The power supply device described in 1.   The determination unit compares the conduction time with a predetermined threshold value, and determines that the diode or the choke coil is short-circuited when the conduction time is continuously lower than the predetermined threshold value a predetermined number of times. The power supply device according to claim 1.   The power supply apparatus according to any one of claims 1 to 3, wherein the switching element is turned off when it is determined by the determination unit that a short circuit has occurred.   5. The power supply device according to claim 1, further comprising a switch that cuts off an AC voltage to the rectifier circuit when it is determined that the determination unit has short-circuited. 6.   6. The switch according to claim 1, further comprising a switch that cuts off a current to a load circuit connected to the power supply device when the determination unit determines that a short circuit has occurred. Power supply.   The television apparatus provided with the power supply device of any one of Claims 1-6.   The electronic device provided with the power supply device of any one of Claims 1-6.

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