JP2810452B2 - Switching power supply - Google Patents

Description

The present invention relates to a switching power supply device that is small and thin.

(B) Conventional technology As shown in Fig. 18, a switching power supply directly converts a commercial AC power supply into a direct current by a rectifying and smoothing circuit (111), and switches by a high frequency, for example, a pulse of 100KHz to 500KHz from an oscillation circuit (121). The transistor (131) is switched, and an output voltage is obtained from a secondary side of a ferrite transformer (141) which is a collector load of the switching transistor (131). The output voltage of the secondary side is detected by a variation of the rectified voltage on the secondary side by an error amplifier (151), and the output is applied to a pulse width modulation circuit (161) via a photocabler. The reference pulse is pulse width modulated to form a stabilizing feedback control system.

Such a switching power supply can replace a conventional low-frequency transformer with a small and lightweight high-frequency transformer (141), which greatly contributes to a reduction in the size and weight of the power supply device. Such a switching power supply is disclosed, for example, in Japanese Utility Model Publication No. 62-19107 (H02).
M 3/335).

However, switching power supplies are destined to generate switching noise, and this noise is
Some sort of noise countermeasure is indispensable so that it does not affect other equipment by superimposing it on the AC line. As a countermeasure, a choke coil serving as a noise filter is inserted into the power supply circuit to remove the switching frequency and its harmonics.

The circuit of a general noise filter is inserted between a commercial AC power supply (101) and a rectifying / smoothing circuit (111) as shown in FIG. L is a common mode choke coil, C1
Is a normal mode noise reduction capacitor, C2, C
Reference numeral 3 denotes a capacitor for reducing noise in both the common mode and the normal mode.

A small common mode choke coil is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 62-53013 (H03H 7/09).

(C) Problems to be Solved by the Invention However, conventional choke coils each have a certain thickness, and have a drawback that they are not suitable for hybrid integrated circuits requiring surface mounting. For this reason, it has been possible to realize a circuit in which only the subsequent circuit after the diode bridge circuit is reduced in size and thickness or a circuit in which the latter circuit and a part of the preceding circuit such as the diode bridge circuit are integrated into one package. Therefore, there is no switching power supply circuit in which all the switching power supply circuits are packaged in one package. Therefore, since the noise filter is provided externally, there is a drawback that the demand for a smaller and thinner electronic device cannot be sufficiently satisfied.

(D) Means for Solving the Problems The present invention has been made in view of the above-mentioned conventional drawbacks, and the data filter (11) constituting the noise filter circuit is replaced with the thin pulse transformer (14) or choke of the preceding stage circuit. The circuit is reduced in size and thickness to about the same as the thickness of the coil (16), and all the circuit components constituting the former-stage circuit and the latter-stage circuit are integrated on the same insulated metal substrate (1), and the metal is fixed via a metal fixing member. The first and second circuits are hermetically sealed using a case material made of the same, thereby realizing a small and thin switching power supply device.

(E) Function According to the present invention, another pulse transformer (14), a choke coil (16), and a first smoothing capacitor (12) are obtained by thinning the data filter (11) of the electronic component for the noise filter circuit. In addition, the height of a conventionally thin component such as the noise filter (9) can be made uniform, so that the noise filter circuit can be housed on the same substrate.
Therefore, the entire switching power supply device can be reduced in size and thickness.

Further, the present invention has a completely shielded structure because the front and rear circuits are completely sealed by the case material via the metal fixing member.

Further, in the present invention, since the fixing member is arranged on the peripheral edge of the substrate, the substrate can be prevented from being bent.

(F) Embodiment As shown in FIG. 1, the switching power supply of the present invention comprises a relatively large insulating substrate (1) and a conductive path (2) having a desired shape formed on the insulating substrate (1). A front circuit (6) and a rear circuit (7) composed of a plurality of electronic components mounted on the first circuit, and a case material (19) for completely sealing the front circuit (6) and the rear circuit (7). .

As the insulating substrate (1) (hereinafter referred to as a substrate), a relatively large substrate having a size of 20 cm × 30 cm is used. As the substrate (1), for example, a phenol substrate, a glass epoxy substrate, or an insulated metal substrate is used. In this embodiment, a metal aluminum substrate having excellent heat dissipation is used, and the surface thereof is coated with an aluminum oxide film by a known anodic oxidation technique. The thickness of the substrate (1) used in the present embodiment is selected from a relatively thick substrate of 1 mm to 4 mm in consideration of heat radiation.

An insulating resin layer (not shown) of 10 to 70 μ thick epoxy or polyimide is adhered to one main surface of the substrate (1), and a 10 to 105 μ thick copper foil (not shown) is further formed on the insulating resin. Are attached together with the insulating resin layer by means such as a roller or a hot press. The copper foil to be adhered on the substrate (1) is designed to have a constant thickness over the entire area of the substrate (1) or to be adhered by partially varying the thickness of the copper foil. In this embodiment, a relatively large current capacity and workability are taken into consideration, and the substrate (1) is used.
It is assumed that a copper foil of 70 μm is adhered over the entire area.

On the copper foil surface provided on one main surface of the substrate (1), a conductive path of a desired shape is exposed by screen printing and masked with a resist, and a noble metal (gold, silver, platinum) plating layer is coated on the copper foil surface. Is plated. Thereafter, the resist is removed, the noble metal plating layer is masked, and the copper foil is etched to form a desired conductive path (2).

A pre-stage circuit (6) on which a plurality of electronic components are mounted on the conductive path (2) to rectify the AC power, and a post-stage circuit (7) for converting the power rectified by the pre-stage circuit (6) to a predetermined output power. ) Are formed on the same plane.

The main electronic components constituting the pre-stage circuit (6) are a capacitor (8), and a capacitor (8) and an LC resonance filter circuit are formed to remove relatively low frequency noise of 10K to 500K in a switching portion. Filter (9) and a rectifier circuit (1) for rectifying AC power to DC power.
0).

 Hereinafter, each main component of the preceding circuit (6) will be described.

The capacitor (8) is not clear from FIG.
It has a rectangular parallelepiped shape of × 25 mm × 8 mm, and the terminals of the capacitor (8) are connected to the conductive path (2) by soldering.

As shown in FIGS. 2 and 3, the noise filter (9) is formed by spirally winding an insulated conductor (9a), sandwiched by insulating thin plates (9b) and (9c), and forming a band of ferrite (9d) near the center thereof. ) Is formed. Its shape is 32mm
It has a flat rectangular parallelepiped shape of × 50 mm × 9 mm, and terminals (9e) provided at four corners are connected to the conductive path (2) by soldering.

As is well known, the rectifier circuit (10) is soldered to the conductive path (2) so that the diode components form a bridge configuration.

Next, the main electronic components constituting the post-stage circuit (7) are data filters (11) for removing high-frequency and low-frequency noises including external noises not removed by the noise filter (9).
A first smoothing capacitor (12) for smoothing the DC power rectified by the rectifier circuit (10), a switching IC (13) for switching and controlling the current flowing through the primary winding of the pulse transformer (14), A pulse transformer (14) having a primary winding and a secondary winding, a rectifier diode (15) for rectifying an output on the secondary winding side converted by the pulse transformer (14), and a pulse transformer (14) Choke coil (16) for accumulating the exciting current output from the controller and releasing energy to an external load, and a second smoothing capacitor (20) for smoothing a ripple current including a ripple component via the choke coil (16) It is composed of

 Hereinafter, each main component of the subsequent circuit (7) will be described.

The most significant feature of the present invention is the data filter (11). Hereinafter, the data filter (11) will be described in detail.

FIG. 4 is a top view of the data filter (11), and FIG.
The figure is a side view of a flat ferrite core, and FIGS. 6A and 6B are a top view and a cross-sectional view of a conductor coated with insulation.

The data filter (11) is a flat ferrite core (11
a) and a plurality of foil-shaped conductors (11b) coated with insulation.

The flat ferrite core (11a) is made of a uniform ferrite material having the same characteristics (eg, Nippon Ferrite GP-
7) is formed by firing. The shape is flat and rectangular parallelepiped, and the through hole (11c) extends so as to be orthogonal to the thin side surface. Although one or more through-holes (11c) are formed, two or more through-holes (11c) are usually provided apart from each other in order to be inserted into a power supply line. Therefore, in the drawing, a flat ferrite core (11a) having two through holes (11c) is shown. Referring to this drawing, the ferrite core (11a) is 46mm x 30m
m × 8mm flat rectangular parallelepiped shape, 46mm through hole (11c)
It extends linearly from the side surface of × 8 mm to the opposing surface, and is located at the center of the thickness of 8 mm. The cross section of the through hole (11c) is 13mm
× 0.6 mm, and the distance between both through holes (11c) (11c) is about 8 mm. This through hole (11c) is formed by forming a groove of 0.3 mm depth in a 4 mm thick ferrite plate and then bonding two ferrite plates together.

Multiple conductors (11b) are tinned annealed copper flat wire (11e)
Are extended in parallel, sandwiched and adhered with polyester (11f). The number of tin-plated annealed copper rectangular wires (11e) is four per conductor (11b), and the thickness is 0.
1 mm and 1.27 mm width were used, and the line pitch was arranged at 2.54 mm. Therefore, the finished thickness of the conductor (11b) is 0.43 mm including the polyester (11f).

The conductor (11b) is inserted one by one into the through hole (11c), and both ends of the conductor (11b) protrude from the ferrite core (11a). Furthermore, the tin-plated annealed copper flat wire (11e) at the end of the conductor (11b) is exposed and used for connecting the data filter to other circuits.

Next, FIG. 7 shows an equivalent circuit diagram of the data filter (11). This data filter (11) uses a polyester (11f) and an L component formed between the conductor (11b) and the ferrite core (11a) as a dielectric layer to form a C formed between the conductor (11b) and the ferrite core (11a). And components. Moreover, since the C component is inserted between the L component and the ferrite ground (FG), it has a function as a common mode noise reduction capacitor. In this embodiment, the L component is about 2 μm.
H and C components have obtained 5 to 25 PF.

8 and 9 show the characteristics of the data filter according to the present invention. FIG. 8 shows the frequency characteristic of the inductance of the data filter (11) specifically described in FIG. 4. The inductance is approximately 2 μH up to approximately 3 MHz, and has approximately 0.7 μH even at 10 MHz. On the other hand, FIG. 9 shows the frequency characteristic of the impedance, which rises sharply from about 3 MHz. As a result, the data filter (11) has a filter effect over a wide band of 50 Hz to about 20 MHz, and can reliably remove switching noise of 500 KHz and its harmonics even in a switching power supply having a switching frequency of 500 KHz.

When the data filter (11) is mounted on the substrate (1), the tip of the conductor (11b) and the conductive path (2)
Is fixed by soldering. More specifically, the data filter (11) is surface-mounted so that the conductor (11b) connects between the conductive paths (2) serving as power supply lines. The height of the data filter (11) should be approximately the same as the height that can be realized by the noise filter (9), the first smoothing capacitor (12), the pulse transformer (14), the choke coil (16), and the like. Is set.

As the first smoothing capacitor (12), a thin electrolytic capacitor having a size of 70 mm × 100 mm × 6 mm is used.
In b), it is connected to the nearby conductive path (2). More specifically, as shown in FIG. 10, the first smoothing capacitor (12) has a connection pin (not shown) provided on the upper surface of the capacitor (12a) facing upward. Insulation plate (12b) with through holes corresponding to the connection pins on the capacitor (12a)
Is arranged. A conductive pattern (12c) for connection extending from the through hole is formed on the upper surface of the insulating plate (12b). When the through-hole is covered with solder, the capacitor (12) and the conductor pattern (12c) are electrically integrated and connected to the conductive path (2).
c) will be arranged on the upper surface side.

As shown in FIG. 11, the switching IC (13) has a conductive path (13c) formed in a desired shape on an insulated aluminum substrate (13a) via an insulating resin layer (13b) such as epoxy or polyimide. Power transistor (13
d), a plurality of circuit elements (13e) such as transistors, chip resistors, and chip capacitors are fixed. The power transistor (13d) and the plurality of circuit elements (13e) mounted on the aluminum substrate (13a) are coated with an epoxy resin (13f). The aluminum substrate (13a) used in this example is 30 mm x 6
It has a size of 0mm. Further, external leads are led out from one peripheral end of the substrate (13a).

The switching IC (13) generates the most heat, and when mounted on the board (1), it is designed to be mounted near the center of the board (1) in consideration of the heat distribution of the heat. You.

When the switching IC (13) is mounted on the board (1), as shown in FIG. 11, the switching IC (1) is mounted on the board (1).
A conductor (13g) protruding from the opposing peripheral edges of 3) is provided, and the switching IC (1h) is mounted with a Z-shaped mounting bracket (13h).
Fix the peripheral edge of 3), solder the conductor (13g) and the bracket (13h) and integrate them. That is, the switching IC (13) is formed in advance in a separate process, and after mounting on the substrate (1) in a plane, the external leads of the switching IC (13) and the conductive path (2) are connected by soldering.

Switching IC located approximately in the center of the board (1)
In the vicinity of (13), a pulse transformer (1
Parts having a certain degree of heat generation, such as 4) and a choke coil (16), are arranged so that heat generated by each part is efficiently radiated using a substrate.

As shown in FIGS. 12 and 13, the pulse transformer (14) is formed by laminating a metal foil (14a) formed in a bellows shape and an insulating layer (not shown) in a plurality of layers and sandwiching them by a ferrite core (14b). Formed. That is, the metal foil (14a) is insulated from the primary winding (14a '), the secondary winding (14a "), and the auxiliary winding (14a) of the auxiliary power supply of the switching IC (13). The connection terminals (14b ′), (14b ″), and (14b) are formed from the respective windings and are connected to a predetermined conductive path (2). Although it is not clear from the figure, the size of this pulse transformer (14) is 30mm x 60mm x 8mm
In the shape of a flat rectangular parallelepiped.

Since the rectifier diode (15) only needs to rectify the output of the pulse transformer (14), a normal electronic component diode is used.

As shown in FIGS. 14 and 15, the choke coil (16) is formed by laminating a metal foil (16a) formed in a bellows shape and an insulating layer (not shown) in a plurality of layers, like the pulse transformer (14). It is formed so as to be clamped by the core (16b).
Connection terminals (16c) are led out from both ends of the metal foil (16a) and connected to a predetermined conductive path (2). Choke coil (1
The size of 6) is not clear from the figure, but 25mm x 60mm x 8mm
In the shape of a flat rectangular parallelepiped.

The second smoothing capacitor (20) is composed of small components like the diode (15).

An external connector (17) for performing AC input is connected to the substrate (1) on which the former-stage circuit (6) and the latter-stage circuit (7) are formed.

The external connector (17) is formed of an insulating resin plate (17c) such as an epoxy resin, and has a fixing region (1) fixed to the substrate (1).
7a) and a connector area (17b) connected to an external circuit. A plurality of through holes (17d) are formed on the peripheral edge of the fixing region (17a), and conductors (17e) (17) are formed on both surfaces so as to include a plurality of the through holes (17d).
e ′) is formed. Each conductor (17e) is placed on the connector area (17b) where the conductors (17e) and (17e ') extend.
(17e ') and a plurality of connection terminals (17f) (17
f ′) is formed. The connection terminal (17f) is a terminal for AC power supply, and the connection terminal (17f ') is a ground terminal for frame ground (earth).

When the external connector (17) is fixed on the substrate (1), the connector area (17b) is arranged so as to protrude and fixed by soldering. At this time, the solder becomes a through hole (17
d) The board (1) and external connector (1
7) is firmly fixed in a small space.
As described above, by using the external connector (17) of the present invention, the connector terminal can be easily and firmly fixed to the metal substrate (1) in a small space.

On the other hand, a lead wire (not shown) for supplying output power to an external load is fixed to the opposite peripheral end of the substrate (1) to which the external connector (17) is fixed.

By the way, the above-mentioned substrate (1) is integrated with the case material (19) via the fixing member (18).

FIG. 1B is a perspective view showing a fixing member (18) used in this embodiment. The fixing member (18) of the present embodiment is used by combining two types of a fixing member (18a) made of aluminum and a fixing member (18b) made of resin.

Each of the fixing members (18a) and (18b) is disposed on the peripheral edge of the substrate (1) in order to prevent warpage caused by the large size of the substrate (1). At this time, the aluminum fixing member (18a) is arranged to the side where the external connector (17) and the external lead are not fixed, and the resin fixing member (18b) is arranged to the external connector (17) and the lead. Will be placed in the direction to be. The respective fixing members (18a) and (18b) arranged on the respective peripheral edges are integrated at each corner with screws (18c). In addition, each fixing member (18
a) A through hole (18d) for fixing is formed at a desired position of (1b), and is fixed to the substrate (1) with screws (not shown).

At this time, a conductive path (2a) for grounding is formed on the substrate (1) on which the fixing member (18a) made of aluminum is disposed, and when the substrate (1) is screwed to the substrate (1) (not shown). Conducted with the ground conductive path (2a).

On the other hand, the resin fixing member (18b) is connected to the external connector (1
7) The lead wire is held between the board (1) and the external connector (17) to prevent peeling of the lead wire.

Each fixing member (18a) (18b) on the peripheral edge of the substrate (1)
Then, as shown in FIG. 1C, a thin switching power supply device is completed by fixing a metal case member (19).

The case member (19) and the respective fixing members (18a) and (18b) are fixed by metal screws (not shown).

As a result, the ground conductive path (2a) formed on the substrate (1) is connected to the case material (1) via the metal fixing member (18a).
9) and becomes the same potential, thus providing a shielding effect.

Further, the heat generated on the substrate (1) is radiated by the substrate (1) and conducted through the metal fixing member (18a) to be further released by the case member (19). That is, heat can be dissipated on both the substrate (1) and the case material (19).

In the present invention, the height of all the components mounted on the substrate (1) is 10 mm or less, so that the power supply unit on which the circuit (6) and the subsequent circuit (7) are mounted can be made ultra-thin. it can. Moreover, as described above, it is possible to realize a fin dedicated for heat dissipation unnecessary.

Hereinafter, a specific example of a switching power supply circuit of a power supply for a computer using the present invention will be described.

FIG. 16 shows a circuit diagram of the switching regulator.
AC voltage AC is first through the capacitor first filter circuit constituting de (31) and a noise filter (32) (33), is rectified by the bridge circuit (34) comprising a diode D ₁ to D _4, followed A second filter circuit (39) comprising a data filter (35) and capacitors (36) (37) (38)
Is applied to The first filter circuit (33) can obtain only a frequency characteristic of a relatively narrow bandwidth due to the conductance C of the capacitor (31) and the inductance L of the noise filter (32), so that low frequency noise of 50 KHz to 500 KHz can be removed. As described above, the second filter circuit (39) can obtain frequency characteristics of a relatively wide bandwidth by the data filter (35).
The value of each element is determined so as to remove high frequency noise of 30 Hz to 30 MHz. The second filter circuit (39)
Even if it is arranged on the commercial AC power supply AC side from the bridge circuit (34), there is no problem in terms of circuit. (40) is a frame ground.

The power supply device full-wave rectified by the bridge circuit (34) is smoothed by the smoothing capacitor (41), and its DC voltage is supplied to the source of the switching transistor (43) via the primary winding of the pulse transformer (42). Has been applied. The high frequency of the oscillation circuit (44), for example, a pulse of 100 kHz to 500 kHz is pulse-modulated by the pulse width modulation circuit (45) and applied to the gate of the switching transistor (43).
The switching transistor (43) is switched by this signal. (46) detects the current flowing through the switching transistor (43) and generates a pulse width modulation circuit (45)
A current transformer (48) protects the switching transistor (43) from the flyback voltage of the pulse transformer (42) while limiting the current flowing through the transistor while protecting the power supply from overload.

When the switching transistor (43) is ON, the voltage induced on the secondary winding side of the pulse transformer (42) due to the input of the DC voltage to the primary winding side of the pulse transformer (42) is a rectifier diode. rectified by D _5, and output is converted into a DC as an output voltage OUT by being smoothed by an output filter (50) comprising a choke coil (48) and capacitor (49). Switching transistor (4
When OFF 3), the energy accumulated in the choke coil (48) is provided as an output voltage OUT it is converted to DC by the diode D ₅ and the output filter (50).

The output voltage OUT is simultaneously applied to an error detection circuit (51) for stabilizing the voltage and an overvoltage detection circuit (52) for protecting internal devices from overvoltage. Error detection circuit (51) includes a zener diode (53) and a resistor R ₁ to create a reference voltage, a transistor (55) for driving the photodiode (54) of the photo-coupler, transistor (5
5) consists of resistors R ₂ and R ₃ for biasing the transistor (55). When the voltage applied to the base of the transistor (55) increases and exceeds the reference voltage of the zener diode (53), a current flows through the photodiode (54). To emit light. The light receiving section (56) of the photocoupler is optically coupled to the photodiode (54), and becomes conductive as the light emission amount of the photodiode (54) increases, and controls the switching transistor (45) by controlling the pulse width modulation circuit (45). 43) It works to reduce the output voltage OUT by narrowing the pulse width applied to the base and shortening the switching period. On the other hand, when the output voltage decreases and the base voltage of the transistor (55) decreases, the light emission amount of the photodiode (54) decreases, and the pulse width modulation circuit (45) operates in the opposite manner as described above to increase the output voltage OUT. Work to let. In this manner, the voltage is stabilized by feeding back the output voltage OUT to the pulse width modulation circuit (45) by the photocoupler. The overvoltage protection circuit (52)
It consists of a Zener diode (57) that produces a reference voltage, and a photodiode (58) of a photothyristor. The Zener diode (57) conducts when the output voltage OUT exceeds the reference voltage, and passes a current to the photodiode (58). The photodiode (58) emits light. The light receiving part (59) of the photothyristor is turned on by the light emission of the photodiode (58) and acts on the current / voltage generating circuit (60) to stop supplying power to each circuit of the switching IC (61). Stop the operation of. By feeding back the output voltage OUT by the photothyristor in this way, the internal device is protected from overvoltage when the output voltage OUT becomes an abnormal value.

By performing the above operation, a commercial AC power supply can be converted to a DC power supply having a predetermined output, and the DC power supply is used as a power supply unit of a computer system.

FIG. 17 is a plan view showing a case where the switching regulator circuit shown in FIG. 16 is mounted on the substrate (1) of the present embodiment, and the reference numerals of the mounted components are shown in the circuit diagram of FIG. The same reference numerals are used.

As shown in FIG. 17, a grounding conductive path (2a) is formed at the peripheral edge and the center of the substrate (1). The ground conductive path (2a) at the center is patterned so as to separate the former circuit (6) and the latter circuit (7). Substrate (1) on which first-stage circuit (6) and second-stage circuit (7) are formed
Each component is connected to the upper conductive path (2). That is,
(17) is an external connector, (31) is a capacitor, (32) is a noise filter, (34) is a rectifier circuit, (35) is a data filter, (41) is a smoothing capacitor, (46) is a current transformer, (61) ) Is a switching IC, (42) is a pulse transformer, (48) is a choke coil, and (49) is a capacitor.

As is clear from FIG. 17, a switching IC (61) having the highest heat generation is arranged at a substantially central portion of the substrate (1).
A pulse transformer (42) and a choke coil (48), which generate heat to some extent, are arranged adjacent to the periphery. Further, the thin data filter (35) is arranged between the power supply lines.

The substrate (1) is completely sealed by using the fixing member and the case material shown in FIGS. 1B and 1C to realize a switching power supply device.

In the present embodiment, the data filter (11) is added to the post-stage circuit (7).
Are arranged, but it is also possible to arrange a data filter (11) on the pre-stage circuit (6) side.

(G) Effects of the Invention As described above, according to the present invention, the data filter (11) constituting the noise filter circuit is also reduced in size and thickness, and the former circuit and the latter circuit of the switching regulator circuit are all made of the same insulated metal substrate. The front and rear circuits are completely sealed by the case material and the board by the metal case material via the metal fixing member. More specifically, since the substrate and the case are electrically connected via the fixing member, they have an advantage that they have a shielding effect and can block external noise.

Further, by using the present invention, there is an advantage that a switching power supply device that is small and thin can be realized. Therefore, there is an advantage that it can further contribute to downsizing of the electronic device.

Further, all the circuit components are surface-mounted on a metal substrate having good heat dissipation and are sealed with a metal case material via a metal fixing member, so that heat generated from the substrate is reduced. The heat is conducted on the surface of the case material by conducting the fixing member. In other words, since both sides of the substrate and the case material serve as heat radiating plates, no special members for radiating heat, such as heat radiating fins, are required at all.

[Brief description of the drawings]

1 to 17 are views for explaining the present invention,
1A to 1C are perspective views showing a switching power supply of the present invention, FIGS. 2 and 3 are plan and side views showing a noise filter (9), respectively, and FIGS. 4 and 5 respectively. 6A and 6B are a plan view and a side view showing the data filter (11), respectively. FIGS.
b) is a plan view and a side view, and FIG. 7 is a data filter (1).
8 and 9 are characteristic diagrams showing the frequency characteristics of the data filter (11), FIG. 10 is a perspective view showing the first smoothing capacitor (12), and FIG. The figures are cross-sectional views showing a switching IC (13), FIGS. 12 and 13 are plan and side views respectively showing a pulse transformer (14), and FIGS. 14 and 15 show choke coils (16), respectively. Top view and side view, Fig. 16 is the circuit diagram of the switching regulator, Fig. 17
The figure is a plan view showing the conductive path (2) pattern on the metal substrate (1) and the arrangement of the main components. FIG. 18 is a circuit diagram for explaining a conventional example. (1) ... metal substrate, (9) ... noise filter, (1
1) Data filter, (13) Switching IC,
(14) ... Pulse transformer, (16) ... Choke coil.

Continuing on the front page (72) Inventor Kenichi Takizawa Gunma Prefecture, Yamada-gun, Oma-machi, Oma 414-1 Tokyo Icy Corporation (72) Inventor Masato Noguchi Gunma, Yamada-gun, Yamada-gun, Oma-machi Oma 414-1 Tokyo Icy Corporation (56 References JP-A-2-163995 (JP, A) JP-A-58-3011 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02M 3/28 H05K 7/14 H05K 7/20 H05K 9/00

Claims (7)

(57) [Claims] 1. A pre-stage circuit having a rectifier circuit connected to a commercial AC power supply and a noise filter for removing noise, a post-stage having a switching circuit for performing a switching operation, and a pulse transformer serving as a load of the switching circuit. A switching power supply device, comprising: a first circuit and a second circuit mounted on the same insulated metal substrate; and a metal fixing member disposed on a peripheral edge of at least one side of the substrate. Wherein the first and second stage circuits are hermetically sealed. 2. The method according to claim 1, wherein the metal fixing member is disposed at an opposite side edge of the substrate, and an insulating fixing member is disposed at another opposing side edge. The switching power supply device according to claim 1. 3. The switching power supply according to claim 1, wherein a plurality of through holes for fixing are provided in the metal fixing member. 4. The switching power supply according to claim 1, wherein a grounding conductive path is disposed on the substrate on which the metal fixing member is disposed. 5. The method according to claim 1, wherein the substrate and the case material are integrated using a plurality of fixing through holes provided in the metal fixing member, and the first and second circuits are hermetically sealed. The switching power supply device according to claim 1. 6. The switching power supply device according to claim 1, wherein the insulating metal substrate is an insulated aluminum substrate. 7. The switching power supply device according to claim 1, wherein said conductive path formed on said insulating metal substrate is made of copper foil.