JP2001286159A - Power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply unit which prevents breakdown of switching elements, increase of noise and maloperation. SOLUTION: A serial circuit of the first and the second switching elements Q1, Q2 and a serial circuit of the third and the fourth switching elements Q3, Q4 are respectively connected with both terminals of a DC power source E in parallel. Between the first to fourth switching elements Q1-Q4, the first and the second switching elements Q1, Q2 are disposed close each other in a substrate and the third and fourth elements Q3, Q4 are disposed close each other in another position of the substrate. A control circuit 3 which controls on and off switching operation of the first to the fourth switching elements Q1-Q4 and a load circuit 1 are disposed in the substrate between the mounting position of the first and the second switching elements Q1, Q2 and that of the third and fourth switching elements Q3, Q4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply.

[0002]

2. Description of the Related Art A circuit diagram of a conventional power supply device is shown in FIG.
The power supply device includes a DC power supply E including a rectifier for rectifying an AC voltage of an AC power supply and a smoothing circuit for smoothing an output of the rectifier; a capacitor C1 for smoothing an output of the DC power supply E;
An inverter circuit 2 having first to fourth switching elements Q1 to Q4, converting a DC voltage into a high-frequency AC voltage by switching the DC voltage with the first to fourth switching elements Q1 to Q4, and supplying the AC voltage to a load circuit 1; , And a control circuit 3 that controls on / off of the first to fourth switching elements Q1 to Q4. The inverter circuit 2 is a full-bridge type inverter circuit. A series circuit of the first and second switching elements Q1 and Q2 and a series circuit of the third and fourth switching elements Q3 and Q4 are connected in parallel to the DC power supply E. Connected and configured. The load circuit 1 includes at least a discharge lamp and a resonance circuit, and is connected between a connection point between the first and second switching elements Q1 and Q2 and a connection point between the third and fourth switching elements Q3 and Q4. Have been.

The control circuit 3 outputs on / off signals a to d to control electrodes of the first to fourth switching elements Q1 to Q4, respectively, and outputs the first and fourth switching elements Q1, Q1 at diagonal positions. The DC voltage is converted to a high-frequency AC voltage by alternately turning on / off the set of Q4 and the set of the second and third switching elements Q2 and Q3.

Incidentally, the first to fourth switching elements Q1 to Q4 are one of the components having the largest temperature rise among the components of the power supply device. Therefore, as shown in FIG. 6, the first to fourth switching elements Q1 to Q4 are attached to the heat sink 4, and the heat sink 4 is thermally coupled to the metal shell 6 to which the circuit board 5 is attached. As a result, heat dissipation is enhanced, and the first to fourth switching elements Q1 to Q4 are prevented from being thermally destroyed. In order to facilitate the work of attaching the heat radiating plate 4 to the outer shell 6, the four switching elements Q1 to Q4 are mounted on the same heat radiating plate 4, so that the four switching elements Q1 to Q4 are They were arranged on the substrate 5 at positions close to each other. The switching elements Q1 to Q4 are disposed substantially at the center of a substantially U-shaped circuit board 5, and one end of the circuit board 5 is connected to a connector C to which a power line from an AC power supply AC is connected.
N1 is disposed, and a connector C to which a load L such as a discharge lamp constituting the load circuit 1 is connected on the other end side of the circuit board 5
N2 and CN3 are arranged (for example, see
No. 5172).

[0005]

As described above, the control circuit 3 alternately sets the set of the first and fourth switching elements Q1 and Q4 and the set of the second and third switching elements Q2 and Q3. During the period when the first and fourth switching elements Q1 and Q4 are turned on and the second and third switching elements Q2 and Q3 are turned off, the capacitor C1 → the first switching element Q1 → Load circuit 1 → 4th
Switch element Q4 → capacitor C1 and the current I
1 flows. On the other hand, the first and fourth switching elements Q
1, Q4 is off, and the second and third switching elements Q
2. During the period when Q3 is turned on, the capacitor C1 → third
Current I in the path of switching element Q3 → load circuit 1 → second switching element Q2 → capacitor C1
2 flows.

By the way, the high-voltage side switching element Q1
Or the current I1 or I2 flowing from Q3 to the load circuit 1 is
Since the four switching elements Q1 to Q4 are arranged in one place as described above to flow into the low voltage side switching element Q4 or Q2, the high voltage side switching elements Q1 and Q3 pass through the inside of the circuit board 5 The current flowing through the discharge lamp L returns to the same position again through the circuit board 5, and the switching current is a large current.
There is a possibility that feedback noise (noise terminal voltage) returning to the C power supply line and radiation noise directly going out to the atmosphere may increase.

Further, four switching elements Q1 to Q4
In order to attach to the same heat sink 4, the four switching elements Q1 to Q4 must be arranged close to each other on the circuit board 5, and the layout of the conductive pattern in the circuit board 5 becomes complicated, As a result, there is a problem that the circuit board 5 becomes large.

Further, as shown in FIG. 6, four switching elements Q1 to Q4 are mounted substantially at the center of the circuit board 5,
When the components of the control circuit 3 are mounted on one side of the circuit board 5, each switching element Q
The wiring lengths from 1 to Q4 to the control electrode and the wiring length of the signal line for detecting the operation state of the discharge lamp L are different,
Further, since the control circuit 3 may be arranged in the vicinity of the signal line through which a relatively large current of a high frequency flows, there is a problem that the control circuit 3 malfunctions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply device capable of reducing the size of a circuit board and preventing an increase in noise and a malfunction. It is in.

[0010]

To achieve the above object, according to the present invention, a series circuit of first and second switching elements and a series circuit of third and fourth switching elements are provided. An inverter circuit configured in parallel with the DC power supply, wherein a load circuit is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements; First and third corner positions
A circuit board on which circuit components of an inverter circuit are mounted in a power supply device for applying an AC voltage to a load circuit by alternately turning on / off a set of switching elements and a set of second and fourth switching elements. At 4
Of the two switching elements, two switching elements are arranged close to each other, and the other two switching elements are arranged close to each other on a portion of the circuit board remote from the mounting portion of the two switching elements. During the period in which the first and fourth switching elements are turned on and the second and third switching elements are turned off, the DC power supply → the first switching element → the load circuit →
A current flows in a path from the fourth switching element to the DC power supply, and the first and fourth switching elements are turned off, and the second and third switching elements are turned on, and the DC power supply to the third switching element. → Load circuit → Second switching element → Current flows through the path of DC power supply, and if four switching elements are arranged close to each other on a circuit board as in a conventional power supply device, four Although the wiring pattern for connecting between the switching element and the load circuit becomes complicated and the circuit board becomes large, in the present invention, two of the four switching elements are brought close to each other and mounted on the circuit board. Since the remaining two switching elements are arranged close to each other on another part of the circuit board, the wiring pattern between each switching element and the load circuit is formed. Come turning is simplified, it is possible to reduce the size of the circuit board, because it shortens the wiring length of the resulting wiring pattern, reduced noise terminal voltage and radiation noise, preventing malfunctions due to noise.

According to a second aspect of the present invention, in the first aspect of the invention, among the four switching elements, the first and second switching elements connected in series are arranged on a circuit board in close proximity to each other, Another third and fourth switching elements are arranged on the circuit board in close proximity to each other, and a current flowing from the first or third switching element on the high voltage side to the load circuit is different from that of the circuit board. Flows into the fourth or second switching element on the low voltage side arranged at the portion of the circuit board, so that the current flowing from the switching element on the high voltage side to the load circuit returns to the same portion of the circuit board as in the conventional power supply device. In other words, the wiring length of the wiring pattern through which a relatively large switching current flows can be shortened to prevent an increase in noise terminal voltage and radiation noise.

According to a third aspect of the present invention, in the second aspect of the present invention, the first and second switching elements are thermally coupled to the same radiator, and the third and fourth switching elements are connected to the radiator. It is characterized in that the first and second switching elements and the third and fourth switching elements, which are arranged close to each other, are coupled to the same radiator, respectively. As a result, the heat radiation effect can be enhanced.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the first and third switching elements on the high voltage side of the four switching elements are arranged on a circuit board in close proximity to each other, and The second and fourth switching elements on the high voltage side are arranged on the circuit board in close proximity to each other, and the first and third switching elements on the high voltage side are arranged on the circuit board in close proximity to each other, and Since the second and third switching elements on the side are arranged close to each other, the voltage at the connection end of the first and third switching elements connected to the positive electrode of the DC power supply and the negative terminal of the DC power supply are connected. It is possible to prevent the voltage at the connection end of the second and fourth switching elements from fluctuating, and to supply a stable voltage to the load circuit.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the first and third switching elements are thermally coupled to the same radiator, and the second and fourth switching elements are connected to the radiator. It is characterized in that the first and third switching elements and the second and fourth switching elements, which are arranged close to each other, are coupled to the same radiator, respectively. As a result, the heat radiation effect can be enhanced, and, similarly to the invention of claim 4, the voltage at the connection terminal of the first and third switching elements connected to the positive electrode of the DC power supply and the negative terminal of the DC power supply Since the voltage at the connection end of the second and fourth switching elements can be prevented from fluctuating, noise radiated from the radiator can be reduced by stabilizing the voltage near the radiator.

According to a sixth aspect of the present invention, in the first aspect, the first switching element on the high voltage side and the second switching element on the low voltage side are connected.
A fourth switching element, which is not connected in series to the first switching element, is arranged on the circuit board in proximity to each other, and the other second and third switching elements are arranged in proximity to each other. Wherein the first and fourth switching elements are mounted on the circuit board, and the first and fourth switching elements are mounted on the circuit board, and the second and third switching elements are mounted on the circuit board. If the load circuit is arranged in a portion of the circuit board between
And a path through which a current flows through the load circuit via the fourth switching element and a path through which the current flows through the load circuit via the second and third switching elements may be arranged on opposite sides of the load circuit. And the magnetic flux generated by the current flowing in each path can be offset each other,
Noise terminal voltage and radiation noise can be reduced, and malfunction due to noise can be prevented.

According to a seventh aspect of the present invention, in the sixth aspect of the invention, the first and fourth switching elements are thermally coupled to the same radiator together, and the second and third switching elements are connected to the radiator. It is characterized by being thermally coupled to another radiator, and the on-periods of the first and fourth switching elements and the on-periods of the second and third switching elements are provided alternately, so that one of the heat radiators is provided. Since the heat generation periods of the first and fourth switching elements mounted on the heat sink and the heat generation periods of the second and third switching elements mounted on the other radiator become discontinuous, respectively, The heat radiation effect can be enhanced.

According to an eighth aspect of the present invention, in the first to seventh aspects of the present invention, the load circuit or the load circuit is connected between the mounting portions of the two switching elements arranged close to each other on the circuit board. One of the terminals is disposed, the wiring length between each switching element and the load circuit can be shortened, and noise such as radiation noise can be reduced.

According to a ninth aspect of the present invention, in the first to eighth aspects of the present invention, on / off of each switching element is controlled between mounting portions of each of two switching elements arranged in close proximity on the circuit board. The present invention is characterized in that the control circuit is provided, and the wiring length between the control electrode of each switching element and the control circuit can be shortened, the influence of noise is reduced, and the switching element can be prevented from malfunctioning.

According to a tenth aspect of the present invention, in the first to ninth aspects of the present invention, the load circuit includes at least a discharge lamp, thereby realizing a lighting fixture having the same operation as the first to ninth aspects. it can.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 of the present invention is shown in FIG.
This will be described with reference to FIG. Since the basic configuration of the power supply device is the same as that of the above-described conventional power supply device, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 1 schematically shows the mounting position of each part on the circuit board 5, and includes four switching elements Q1 to Q1.
Of the Q4, the first and second switching elements Q1 and Q2 constituting one arm are mounted on the circuit board 5 so as to be close to each other, and the third and fourth switching elements Q3 constituting the other arm are provided. , Q4 are mounted on other parts of the circuit board 5 close to each other.

The first and second switching elements Q1 and Q2 mounted close to the circuit board 5 are thermally coupled to the same radiating plate 7a and close to other portions of the circuit board 5. The mounted third and fourth switching elements Q3, Q4 are thermally coupled to another heat sink 7b.

The first and second switching elements Q
Circuit components of the control circuit 3 and the load circuit 1 are mounted on a portion of the circuit board 5 between the mounting portion of the first and the second switching elements Q3 and the mounting portion of the third and fourth switching elements Q3 and Q4. A connector (not shown) for connecting a load as described above is mounted. Here, the circuit components constituting the control circuit 3 are generally constituted by surface mount products, and the circuit components of the control circuit 3 are mounted on the surface opposite to the surface of the circuit board 5 on which the connector is mounted. This prevents interference with the connector.

When the four switching elements Q1 to Q4 are arranged close to each other as in the conventional power supply device, the wiring pattern connecting the four switching elements and the load circuit becomes complicated. Although the circuit board becomes large, the four switching elements Q1 to
Of the Q4, two switching elements Q1 and Q2 are arranged close to the circuit board 5, and the other two switching elements Q3 and Q4 are arranged close to another part of the circuit board 5. Therefore, the wiring pattern between each of the switching elements Q1 to Q4, the control circuit 1 and the load circuit 3 can be easily arranged, and the size of the circuit board 5 can be reduced. As a result, the wiring length of the wiring pattern can be reduced. Because it can be shortened,
Noise terminal voltage and radiation noise are reduced, and malfunction due to noise can be prevented.

The current flowing from the high-voltage side switching element Q1 or Q3 to the load circuit 1 is applied to the low-voltage side switching element Q4 or Q4 mounted on another part of the circuit board 5.
2, and the four switching elements Q1 to Q1
The current flowing from the high-voltage side switching element Q1 or Q3 to the load circuit 1 through the circuit board 5 is returned to the original position through the circuit board 5 as in the case where Q4 is mounted in one place. Will not return, shorten the wiring length of the wiring pattern through which a relatively large switching current flows,
It is possible to prevent noise terminal voltage and radiation noise from increasing.

In this embodiment, the first and second switching elements Q1 and Q2 arranged close to the heat sink 7a are thermally coupled, and the third switching element Q1 arranged close to the heat sink 7b.
And the fourth switching elements Q3 and Q4 are thermally coupled. However, depending on the shape and size of the radiator plate, the switching elements Q1 to Q4 are connected as shown in FIG. You may make it attach to each heat sink 8a-8d.

Embodiment 2 FIG. 3 shows Embodiment 2 of the present invention.
This will be described with reference to FIG. Since the basic configuration of the power supply device is the same as that of the above-described conventional power supply device, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 3 schematically shows the mounting position of each part on the circuit board 5, and includes four switching elements Q1 to Q4.
The switching elements Q1 and Q3 on the high voltage side of Q4 are mounted close to each other on the circuit board 5, and the switching elements Q2 and Q4 on the low voltage side are mounted close to each other on the circuit board 5 and mounted. ing.

Then, the first and second switching elements Q1 and Q2 mounted close to the circuit board 5 are thermally coupled to the same radiating plate 9a, and close to other portions of the circuit board 5. The mounted third and fourth switching elements Q3, Q4 are thermally coupled to another heat sink 9b.

The first and second switching elements Q
Circuit components of the control circuit 3 and the load circuit 1 are mounted on a portion of the circuit board 5 between the mounting portion of the first and the second switching elements Q3 and the mounting portion of the third and fourth switching elements Q3 and Q4. A connector (not shown) for connecting a load as described above is mounted. Here, the circuit components constituting the control circuit 3 are generally constituted by surface mount products, and the circuit components of the control circuit 3 are mounted on the surface opposite to the surface of the circuit board 5 on which the connector is mounted. This prevents interference with the connector.

When four switching elements Q1 to Q4 are arranged close to each other as in a conventional power supply device, a wiring pattern for connecting the four switching elements and the load circuit becomes complicated. Although the circuit board becomes large, the four switching elements Q1 to
Of the Q4, two switching elements Q1, Q3 are arranged close to the circuit board 5, and the other two switching elements Q2, Q4 are arranged close to another part of the circuit board 5. Therefore, the wiring pattern between each of the switching elements Q1 to Q4, the control circuit 1 and the load circuit 3 can be easily arranged, and the size of the circuit board 5 can be reduced. As a result, the wiring length of the wiring pattern can be reduced. Because it can be shortened,
Noise terminal voltage and radiation noise are reduced, and malfunction due to noise can be prevented.

The current flowing from the high-voltage side switching element Q1 or Q3 to the load circuit 1 is applied to the low-voltage side switching element Q4 or Q4 mounted on another part of the circuit board 5.
2, and the four switching elements Q1 to Q1
As in the case where Q4 is mounted in one place, the current flowing from the high-voltage side switching element Q1 or Q3 to the load circuit 1 through the circuit board 5 passes through the circuit board 5 to the original portion. Will not return, shorten the wiring length of the wiring pattern through which a relatively large switching current flows,
It is possible to prevent noise terminal voltage and radiation noise from increasing.

Furthermore, the first and third switching elements on the high voltage side are arranged close to each other, and the second and fourth switching elements on the low voltage side are arranged close to each other. Switching element Q1 or Q
3 and the voltage difference between the low-voltage side switching element Q4 or Q2 can be prevented from fluctuating, and stable power can be supplied to the load circuit 1. Also, one heat sink 9a
The switching elements Q1 and Q3 on the high voltage side are attached to the switching element Q1, and the switching element Q
2 and Q4 are attached, so that the heat sinks 9a and 9b
The nearby electric potential is stabilized, and radiation noise generated from the heat radiating plates 9a and 9b can be reduced.

In this embodiment, the first and third switching elements Q1 and Q3 arranged close to the heat radiating plate 9a are thermally coupled, and the second and third switching elements Q1 and Q3 arranged close to the heat radiating plate 9b.
And the fourth switching elements Q2 and Q4 are thermally coupled. However, depending on the shape and size of the heat radiating plate, the switching elements Q1 to Q4 are individually connected to the heat radiating plate in consideration of heat radiation efficiency. You may make it attach.

(Embodiment 3) FIG. 4 shows Embodiment 3 of the present invention.
This will be described with reference to FIG. Since the basic configuration of the power supply device is the same as that of the above-described conventional power supply device, the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 4 schematically shows the mounting position of each part on the circuit board 5, in which a first switching element Q1 on the high voltage side and two switching elements Q2, Q4 on the low voltage side.
And a fourth switching element Q4 that is not connected in series to the first switching element Q1 is arranged on the circuit board 5 so as to be close to each other, and the other second and third switching elements Q2 and Q3 are mutually connected. Circuit board 5 in close proximity
It is located above.

Then, the first and fourth switching elements Q1 and Q4 mounted close to the circuit board 5 are thermally coupled to the same radiating plate 10a and close to other portions of the circuit board 5. The mounted second and third switching elements Q3, Q4 are thermally coupled to another heat sink 10b.

The first and second switching elements Q
Circuit components of the control circuit 3 and the load circuit 1 are mounted on a portion of the circuit board 5 between the mounting portion of the first and the second switching elements Q3 and the mounting portion of the third and fourth switching elements Q3 and Q4. A connector (not shown) for connecting a load as described above is mounted. Here, the circuit components constituting the control circuit 3 are generally constituted by surface mount products, and the circuit components of the control circuit 3 are mounted on the surface opposite to the surface of the circuit board 5 on which the connector is mounted. This prevents interference with the connector.

When four switching elements Q1 to Q4 are arranged close to each other as in a conventional power supply device, a wiring pattern for connecting between the four switching elements and the load circuit becomes complicated. Although the circuit board becomes large, the four switching elements Q1 to
Of the Q4, two switching elements Q1 and Q4 are arranged close to the circuit board 5, and the other two switching elements Q2 and Q3 are arranged close to another part of the circuit board 5. Therefore, the wiring pattern between each of the switching elements Q1 to Q4, the control circuit 1 and the load circuit 3 can be easily arranged, and the size of the circuit board 5 can be reduced. As a result, the wiring length of the wiring pattern can be reduced. Because it can be shortened,
Noise terminal voltage and radiation noise are reduced, and malfunction due to noise can be prevented.

In the control circuit 3, the set of the first and fourth switching elements Q1 and Q4 and the set of the second and third switching elements Q2 and Q3 are alternately turned on / off. And the fourth switching elements Q1, Q4 are turned on, and the second and third switching elements Q2, Q3
Is turned off, the current I1 flows through the path of the capacitor C1, the first switching element Q1, the load circuit 1, the fourth switching element Q4, and the capacitor C1.
On the other hand, the first and fourth switching elements Q1, Q4 are turned off, and the second and third switching elements Q2, Q3
Is turned on, the current I2 flows through the path of the capacitor C1, the third switching element Q3, the load circuit 1, the second switching element Q2, and the capacitor C1.
Here, in the circuit board 5, the first to fourth switching elements Q1 to Q4 and the load circuit 1 are mounted at the positions as described above, and the current path through which the current I1 flows and the current I2
Is arranged in the opposite direction to the load circuit 1, the magnetic flux generated by the current I1 and the magnetic flux generated by the current I2 can be canceled each other, and the noise terminal voltage and radiation noise Is reduced, and malfunctions caused by noise can be reduced.

In this embodiment, the first and fourth switching elements Q1 and Q4 arranged close to the heat sink 10a are thermally coupled, and the second and third switching elements Q11 and Q4 arranged close to the heat sink 10b. The switching elements Q2 and Q3 are thermally coupled. However, depending on the shape and size of the heat sink, the switching elements Q1 to Q4 are attached to individual heat sinks in consideration of heat dissipation efficiency. Is also good.

[0043]

As described above, the first aspect of the present invention provides the first aspect.
And an inverter circuit configured by connecting a series circuit of the second and third switching elements and a series circuit of the third and fourth switching elements in parallel to a DC power supply.
A load circuit is connected between the connection point of the switching element and the connection point of the third and fourth switching elements, and the set of the first and third switching elements and the second
And a fourth set of switching elements which are alternately turned on / off to apply an AC voltage to the load circuit. In a power supply apparatus, a circuit board on which circuit components of an inverter circuit are mounted has four switching elements. Of which, 2
The two switching elements are arranged close to each other, and the remaining two switching elements are arranged close to each other on a portion of the circuit board remote from the mounting portion of the two switching elements. During a period in which the first and fourth switching elements are turned on and the second and third switching elements are turned off, a current flows through a path of DC power supply → first switching element → load circuit → fourth switching element → DC power supply. Flows, the first and fourth switching elements are turned off, and the second and third switching elements are turned on. When the current flows through the path, and four switching elements are arranged close to each other on the circuit board as in a conventional power supply, four switches are used. The wiring pattern for connecting between the switching element and the load circuit is complicated, and the circuit board becomes large. In addition, since the remaining two switching elements are arranged close to each other in another part of the circuit board, the wiring pattern between each switching element and the load circuit can be easily routed, and the circuit board can be reduced in size. Therefore, since the wiring length of the wiring pattern can be shortened, noise terminal voltage and radiation noise can be reduced, and malfunction due to noise can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, of the four switching elements, the first switching element is connected in series.
And the second switching element is arranged on the circuit board in close proximity to each other, and the other third and fourth switching elements are arranged on the circuit board in close proximity to each other. Alternatively, the current flowing from the third switching element to the load circuit flows into the low-voltage fourth or second switching element disposed at another part of the circuit board, and thus the current on the high-voltage side as in a conventional power supply device. The current flowing from the switching element to the load circuit does not return to the same part of the circuit board, and the wiring length of the wiring pattern through which a relatively large switching current flows is shortened, increasing the noise terminal voltage and radiation noise. There is an effect that can be prevented.

According to a third aspect of the present invention, in the second aspect, the first and second switching elements are thermally coupled to the same radiator together, and the third and fourth switching elements are connected to the radiator. It is characterized in that the first and second switching elements and the third and fourth switching elements, which are arranged close to each other, are coupled to the same radiator, respectively. Therefore, there is an effect that the heat radiation effect can be enhanced.

According to a fourth aspect of the present invention, in the first aspect of the present invention, among the four switching elements, the first and third switching elements on the high voltage side are arranged close to each other on the circuit board, and The second and fourth switching elements on the high voltage side are arranged on the circuit board in close proximity to each other, and the first and third switching elements on the high voltage side are arranged on the circuit board in close proximity to each other, and Since the second and third switching elements on the side are arranged close to each other, the voltage at the connection end of the first and third switching elements connected to the positive electrode of the DC power supply and the negative terminal of the DC power supply are connected. Thus, the voltage at the connection end of the second and fourth switching elements can be prevented from fluctuating, and a stable voltage can be supplied to the load circuit.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the first and third switching elements are thermally coupled to the same radiator, and the second and fourth switching elements are connected to the radiator. It is characterized in that the first and third switching elements and the second and fourth switching elements, which are arranged close to each other, are coupled to the same radiator, respectively. As a result, the heat radiation effect can be enhanced, and, similarly to the invention of claim 4, the voltage at the connection terminal of the first and third switching elements connected to the positive electrode of the DC power supply and the negative terminal of the DC power supply Second
Further, since it is possible to prevent the voltage at the connection end of the fourth switching element from fluctuating, it is possible to reduce the noise radiated from the radiator by stabilizing the voltage near the radiator.

According to a sixth aspect of the present invention, in the first aspect of the present invention, a fourth switching element which is not connected in series to the first switching element on the high voltage side and the first switching element of the two switching elements on the low voltage side. And a second switching element and a third switching element are disposed on the circuit board so as to be close to each other. When the load circuit is disposed on a portion of the circuit board between the mounting portions of the first and fourth switching elements and the mounting portions of the second and third switching elements, Disposing a path through which current flows through the load circuit via the fourth switching element and a path through which current flows through the load circuit via the second and third switching elements on opposite sides of the load circuit. Can, because the magnetic flux generated by a current flowing through each path can be canceled each other to reduce the noise terminal voltage and radiation noise, there is an effect that a malfunction due to noise can be prevented.

According to a seventh aspect of the present invention, in the sixth aspect, the first and fourth switching elements are thermally coupled to the same radiator together, and the second and third switching elements are connected to the radiator. It is characterized by being thermally coupled to another radiator, and the on-periods of the first and fourth switching elements and the on-periods of the second and third switching elements are provided alternately, so that one of the heat radiators is provided. Since the heat generation periods of the first and fourth switching elements mounted on the heat sink and the heat generation periods of the second and third switching elements mounted on the other radiator become discontinuous, respectively, There is an effect that the heat radiation effect can be enhanced.

According to an eighth aspect of the present invention, in the first to seventh aspects of the present invention, a load circuit or a connection circuit for connecting a load circuit is provided between mounting portions of two switching elements arranged in close proximity on the circuit board. It is characterized in that one of the terminals is arranged, and has an effect that the wiring length between each switching element and the load circuit can be shortened, and noise such as radiation noise can be reduced.

According to a ninth aspect of the present invention, in the first to eighth aspects of the present invention, the on / off of each switching element is controlled between the mounting portions of the two switching elements arranged in close proximity on the circuit board. The control circuit is arranged, the wiring length between the control electrode of each switching element and the control circuit can be shortened, the effect of the noise is less, and the switching element can be prevented from malfunctioning. There is.

According to a tenth aspect of the present invention, in the first to ninth aspects of the present invention, the load circuit includes at least a discharge lamp, and a lighting fixture having the same operation as the first to ninth aspects is realized. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically illustrating a component arrangement of a power supply device according to a first embodiment.

FIG. 2 is an explanatory diagram schematically illustrating a component arrangement of another power supply device according to the first embodiment.

FIG. 3 is an explanatory diagram schematically illustrating a component arrangement of a power supply device according to a second embodiment.

FIG. 4 is an explanatory diagram schematically illustrating a component arrangement of a power supply device according to a third embodiment.

FIG. 5 is a circuit diagram of a conventional power supply device.

FIG. 6 is a schematic configuration diagram of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Load circuit 3 Control circuit Q1-Q4 1st-4th switching element

Continued on the front page (72) Inventor Naoji Yokota 1048 Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Works, Ltd.

Claims (10)

[Claims] An inverter circuit configured by connecting a series circuit of first and second switching elements and a series circuit of third and fourth switching elements in parallel to a DC power supply; The second switching element connection point;
A load circuit is connected between the first switching element and the fourth switching element, and the first and third switching element sets and the second and fourth switching element sets at diagonal positions are alternately arranged. In a power supply device for applying an AC voltage to a load circuit by turning on / off, in a circuit board on which circuit components of an inverter circuit are mounted, two switching elements out of four switching elements are brought close to each other. A power supply unit, wherein the remaining two switching elements are arranged close to each other on a portion of the circuit board remote from the mounting portion of the two switching elements. A first switching element connected to the first switching element and a second switching element connected to the first switching element on the circuit board; The power supply device according to claim 1, wherein the power supply device is disposed on the circuit board in close proximity. 3. The radiator according to claim 1, wherein said first and second switching elements are thermally coupled to a same radiator, and said third and fourth switching elements are thermally coupled to a radiator different from said radiator. The power supply device according to claim 2, wherein 4. A high-voltage-side first and third switching element is disposed on a circuit board in close proximity to each other, and a low-voltage-side second and fourth switching element is connected to each other. 2. The power supply device according to claim 1, wherein the power supply device is arranged on the circuit board in close proximity. 5. The radiator according to claim 1, wherein the first and third switching elements are thermally coupled to the same radiator, and the second and fourth switching elements are thermally coupled to a radiator different from the radiator. The power supply device according to claim 4, wherein 6. A circuit board in which a first switching element on the high voltage side and a fourth switching element not connected in series to the first switching element of the two switching elements on the low voltage side are brought close to each other on the circuit board. The power supply device according to claim 1, wherein the second and third switching elements are arranged on the circuit board so as to be close to each other. 7. The radiator according to claim 1, wherein the first and fourth switching elements are thermally coupled to the same radiator, and the second and third switching elements are thermally coupled to a radiator different from the radiator. The power supply device according to claim 6, wherein 8. A circuit board, wherein one of a load circuit and a connection terminal to which the load circuit is connected is arranged between mounting portions of each of two switching elements arranged close to each other. Item 8. The power supply device according to any one of Items 1 to 7. 9. The circuit board according to claim 1, wherein a control circuit for controlling on / off of each switching element is disposed between the mounting portions of each of the two switching elements arranged close to each other. 9. The power supply according to any one of claims 8 to 8. 10. The power supply device according to claim 1, wherein the load circuit includes at least a discharge lamp.