JPH08316054A - Thin transformer - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] The present invention relates to a thin transformer used in an electric device, and provides a thin transformer using a laminated coil of high quality, low loss and capable of supporting high frequency at low cost. It is a thing. [Structure] An electric wire having a self-bonding layer and an insulating coating layer and having a rectangular cross section is used, and a coil formed in a spiral shape in a single layer so as to be flat in the longitudinal direction of the cross section of the electric wire It is used for at least one of the wires 4a, 4b and the secondary winding 5, and all of the primary and secondary windings (4a, 4b, 5) are alternated so as to be face-to-face with one winding and have substantially the same winding width. A laminated coil in which each layer of windings is laminated, and one of the primary winding and the secondary winding is divided into windings, and the windings of each layer of the divided windings are connected in parallel or in series. Was used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin transformer using a spiral winding used in various electronic devices.

[0002]

2. Description of the Related Art In recent years, transformers meet the technical needs of higher frequency, smaller size, thinner shape and higher performance, and printed coil laminated transformers using print etching technology, punched coil laminated formed by punching copper plates. A transformer having a structure or a spiral coil laminated structure in which electric wires are formed in a spiral shape has been developed.

However, in reality, in addition to the above-mentioned technical needs, there is a strong demand for thorough cost reduction as a background of the times, and without this point, practical application is not possible.

In order to provide a thin transformer at low cost, what laminated coil is formed and how is it. However, the printed coil produced by the etching method increases the cost and increases the current capacity. In addition, a coil with a punching method requires a metal mold for reasons such as a limit, and in consideration of cost and versatility, a spiral coil laminated transformer with electric wires formed in a spiral shape is adopted. Is increasing.

In addition, the power supply unit is small and thin,
The demand for cost reduction is increasing.

Hereinafter, a conventional thin transformer using a laminated coil using a spiral winding will be described with reference to FIGS.

In the figure, 1 is a magnetic core, 2 is a spiral winding,
Reference numeral 3 is an insulating paper, 4 is a primary winding, 5 is a secondary winding, and 6 is a tertiary winding. The configuration will be described in more detail with reference to FIG.
After the winding 2 formed by spirally winding the electric wire alone and the insulating paper 3 are alternately laminated to complete the laminated coil,
Magnetic core 1 forming a closed magnetic circuit from the direction in which the coils are stacked
To complete the thin transformer body. The spiral winding 2 may be a spiral punching coil made by punching a thin plate conductor.

In FIG. 17, two sets of windings 2 are alternately laminated. However, if the transformer has a primary winding and a secondary winding, the same applies to two or more sets. Is. FIG. 16 shows another conventional technique, which is a thin transformer in which the winding 2 is laminated in three layers. Further, FIG. 15A shows a conventional thin transformer using a spiral laminated coil, in which a primary winding 4, a secondary winding 5 and a tertiary winding 6 are laminated while sandwiching an insulating paper 3. It was done.

Incidentally, FIG. 15B shows an example of a power supply circuit using the thin transformer of FIG.
Is connected to the primary winding 4, and the tertiary winding 6 is connected to the control circuit 9 via the rectifying and smoothing circuit of the diode 10 and the capacitor 11. The output of the control circuit 9 is the other end of the primary winding 4. The primary switching element (FET) 8 connected to is turned on and off to drive the primary side. A load 14 is connected to the secondary winding 5 via a rectifying / smoothing circuit including a diode 12 and a capacitor 13.

[0010]

However, as shown in FIG.
In the case of using the spiral laminated coil of (a), 1
Since the secondary winding 4, the secondary winding 5 and the tertiary winding 6 are formed by spirally winding electric wires each having a circular cross section, when the wire diameter is selected according to the flowing current, the wire diameter becomes various. ,
The thickness direction of the wire varies, resulting in quality loss including electrical performance. Also, if the current becomes large, the wire diameter also becomes large, which hinders miniaturization and thinning.In addition, when the transformer is driven at high frequency, the AC resistance increases due to the skin effect, resulting in increased loss and high efficiency. Will hinder conversion.

In order to solve this, a thin plate-shaped laminated coil is used as a high frequency driving coil by a print etching or a thin plate-shaped conductor punching method. In the print etching, the cost and versatility are as described above. Is not appropriate. In addition, even if a thin plate-shaped conductor is manufactured by a punching method using a spiral punching coil, preparing various kinds of punching dies causes an increase in production cost.

The number of times the primary switching element (FET) 8 shown in FIG. 15 (b) is turned on and off is called the switching drive frequency.
00kHz is the current industry standard. Downsizing this power supply,
In order to reduce the thickness and increase the performance, technological development for increasing the drive frequency of the power supply is being researched.

However, since the power source is driven at a high frequency in reality, the thin transformer becomes expensive if it is manufactured by the above-mentioned printed etching coil or punching coil.
Cost and versatility are problems, and it has not spread. In order to commercialize and spread the high frequency drive of the power source, a low cost and versatile high frequency compatible component is required, and the key part is said to be a transformer.

The present invention solves the above problems by using a general-purpose, low-loss, high-frequency-compatible laminated coil that uses a spiral winding and has little quality loss including electrical performance. The purpose is to provide a thin transformer.

[0015]

In order to solve the above problems, the thin transformer of the present invention uses an electric wire having a self-bonding layer and an insulating coating layer and having a rectangular cross section. A single coil, which is spirally formed in one layer so as to be flat in the longitudinal direction, is used for at least one of the primary winding and the secondary winding. The windings of the respective layers are alternately laminated so as to have the same winding width and face each other, and at least one of the primary winding and the secondary winding is divided into windings, and each layer of the divided windings is formed. Is characterized in that a laminated coil is constituted so that the windings of (1) are connected in parallel or in series, and a magnetic core constituting a closed magnetic circuit is incorporated from the direction in which the coils are laminated.

[0016]

With the above structure, the space between wires is eliminated and the space utilization rate is improved, so that the space factor of the winding is improved, the thickness of the winding is thin, and the primary and secondary facing areas are large and the distance is large. Since it is formed in a small amount, the increase in AC resistance due to the skin effect is prevented, the coupling between the primary and secondary windings is strengthened, and the loss at high frequencies can be reduced. Moreover, even if the thickness of the wire is unified, the cross-sectional area can be changed, so that the thickness can be standardized, and variations in production and performance can be reduced. Furthermore, the coil alone can maintain its shape, making it easy to handle.
A thin coil can be easily manufactured by the winding method.

[0017]

【Example】

(Embodiment 1) Hereinafter, a first embodiment which is an embodiment of a thin transformer of the present invention will be described with reference to FIGS. Four
Reference numerals a and 4b are primary split windings, and 5a and 5b are secondary split windings, each of which is composed of a spiral winding 2a made of a rectangular wire.

The structure will be described in more detail below.
As shown in Fig. 2, a rectangular wire having a self-bonding layer and an insulating coating layer and having a rectangular cross section is formed in a spiral shape with a single winding width so as to be flat in the longitudinal direction of the cross section. While
The shape is fixed using the fusion layer and the primary split winding 4a,
4b and the secondary winding 5 are prepared. Further, as shown in FIG. 1 (a), the prepared windings are alternately arranged so as to face each other while inserting the insulating paper 3 between the respective layers. The winding is laminated to complete the laminated coil. A thin transformer is completed by incorporating the magnetic core 1 forming a closed magnetic circuit from the direction in which the coils are stacked, as in the prior art shown in FIG. In addition, the connection of the laminated coil in this embodiment is divided into the primary windings 4 as shown in FIGS. 1B and 1C.
The a and 4b may be connected in parallel or in series.

According to the above structure, since the electric wire having the rectangular cross section with the insulating coating layer is used, the space gap is smaller than that of the conventional electric wire having the circular cross section, and the coil manufactured by etching is used. No wire gap is required unlike the punched thin plate coil, and as a result, the winding space factor is improved as compared with the conventional coil. In addition, an electric wire having a rectangular cross section is formed in a spiral shape with substantially the same winding width in a single layer so as to be flat in the longitudinal direction, and windings of the respective layers are alternately laminated so as to face each other. Since the secondary windings 4a and 4b are connected in parallel or in series, the thickness of the windings is thin, the primary and secondary facing areas are large, and the distance between the primary and secondary can be reduced. As a result, an increase in AC resistance due to the skin effect of the wire material due to higher frequencies is prevented, and the coupling between the primary and secondary windings is strengthened, so that low loss at high frequencies is realized.

Further, since the electric wire having a rectangular cross section is wound so as to be flat in the longitudinal direction, the cross sectional area can be changed even if the thickness of the wire is uniform, and the wire can be used for various current capacities. The thickness can be standardized and variations in production and performance can be reduced.

Further, the surface pressure at the cross portion with the winding in the rectangular wire lead-out portion 2b of FIG. 2 can be reduced and the reliability is improved. Further, since the electric wire with the self-bonding layer is used, the shape of the coil alone can be maintained, which facilitates the handling in the subsequent process, and the thin coil can be easily manufactured by the winding method.

Although only the primary winding is divided in the above description, the secondary winding is also divided to form the secondary divided windings 5a and 5b as shown in FIG. By connecting the secondary side in parallel or in series as shown in (b) and (c), the coupling between the primary and secondary windings can be further enhanced, so that the loss at high frequencies can be further reduced. .

4 (a) and 4 (b) show another example of an electric wire having a rectangular cross section used in the present invention. In the drawings, the relationship between the B dimension and the A dimension is B ≧ A. If so, the effect is the same whether it is an ellipse or an ellipse.

Further, in this embodiment, although the method of manufacturing the spiral coil for forming the single coil is not explained, the insulating coated electric wire is used for spiral winding, and then the adhesive, It may be manufactured by fixing with a fusion material, resin or the like so that the shape can be maintained.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIGS.

Basically, FIG. 15 to FIG.
7, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals and detailed description will be omitted.
1 is different from that of FIG. 1 in that a primary auxiliary winding called a tertiary winding 6 is provided on the upper layer of the primary split winding 4a in FIG.
In FIG. 5 (b), it is provided in the same layer as the primary split winding 4a with the same thickness as the other spiral windings. FIG. 5 (c)
The power supply circuit using the thin transformer of this embodiment is shown in FIG.
The circuit is configured in the same way as the circuit of (b).

According to the above structure, even if the cross-sectional area of the tertiary winding 6 is different from that of the primary winding or the secondary winding, the thickness can be the same, so that there is no step when the coils are laminated, so that the manufacturing quality is stable. At the same time, since the coupling with other windings is also stable, the unique effect that the control performance is also stable can be obtained.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to FIGS. 6 is a cross-sectional view of the laminated coil of the thin transformer, and the same parts as those of the embodiment of FIG.

FIG. 7 shows the experimental results showing the relationship between the AC resistance increase rate and the drive frequency in the transformer assembled state (solid line) and the coil alone state (broken line). The AC resistance increase rate is the frequency as shown in FIG. It tends to increase with increasing. This is caused by the thickness of the material, and the skin effect (current concentrates on the surface of the wire at high frequencies, causing a substantial increase in AC resistance. This current distribution bias phenomenon) and the proximity of the wire This is caused by the proximity effect (a current flows in the same direction and the current distribution is biased outward when two conductors approach each other). Originally, if the coil is a single unit, the rate of increase in AC resistance increases due to the skin effect and the proximity effect. However, as shown in FIG. 7, a transformer assembly completed product that incorporates a magnetic core has a coil up to a certain frequency range. The rate of increase in AC resistance is lower than that of the single unit.

This is because the primary winding and the secondary winding have currents flowing in opposite directions, so that the current distribution is more uniform than in the case of currents in the same direction, the AC resistance is smaller, and a magnetic core is incorporated. This is because when the transformer is assembled, the magnetic influence is increased and this tendency is strengthened. This phenomenon is that the proximity effect acts in the assembled state of the transformer and conversely the increase of the AC resistance is suppressed, and this phenomenon is hereinafter referred to as the canceling effect.

From the above phenomenon, the following consideration and experiment were conducted. (1) Setting of effective means for increasing the coupling of windings (considering the winding configuration) (2) Considering compatibility between the upper limit f of the drive frequency in the power supply and the setting of the optimum winding thickness t ₀ , When the AC resistance increase rate of the transformer is below a certain specific frequency, the cancel effect is effectively used to reduce the AC resistance increase rate of the transformer, and it is possible to provide a transformer with low loss.

In order to further confirm the above consideration, in the laminated coil having the basic structure as shown in FIG. 8, while varying the winding thickness t, the relationship between the AC resistance increase rate and the frequency in each thickness as in FIG. Then, the frequency A at which the canceling effect was generated was determined.

In this experiment, the primary split windings 4a and 4b and the secondary winding are alternately laminated as a means for enhancing the coupling of the windings described in the above consideration (1).

The above experimental results are shown in (Table 1).

[0035]

[Table 1]

From Table 1, when the winding thickness is 0.3 mm, the canceling effect does not occur. With a winding thickness of 0.2 mm, 4
A cancellation effect occurs at frequencies of 00 to 900 kHz or less. The thinner the thickness is, the frequency A at which the canceling effect occurs
Will be higher. The frequency A at which the cancellation effect occurs is frequency A
Occurs at 1.5 to 2.86 times the skin thickness δ of the copper. This means that the winding thickness is approximately 3 with skin depth δ.
It is shown that if the thickness is about double, the canceling effect occurs at the frequency around that.

In conclusion, if the upper limit of the driving frequency in the power source is set to about 3 times the skin depth δ of the copper at that frequency, the cancellation effect can be utilized, so that the AC resistance can be reduced and standardized at the same time. It could be confirmed.

From this, if an effective means for enhancing the coupling of the windings is provided, the optimum thickness condition t ₀ of the windings when copper is used as the wire material in the transformer assembly is 0.3 mm> t _0. ≈3 × δ where δ: skin depth, for copper δ = 66.1 / √f (m
m) f: It should be set to the upper limit value (Hz) of the drive frequency at the power supply.

As described above, according to the configuration of this embodiment,
(1) Setting effective means for increasing the coupling of windings, and (2)
The upper limit value f of the drive frequency in the power source and the optimum thickness t _{0 of the} winding
Since it has both of the setting conditions of, the AC resistance can be reduced and the standardization can be achieved at the same time, the loss can be significantly reduced during the transformer assembly, the amount of the wire material can be effectively used, and the standardized optimum design can be achieved. The effect is from Example 1
In addition to the effect of 2, it is possible to make a thin and inexpensive thin transformer.

It should be noted that it is easily conceivable that the optimum thickness condition t ₀ of the winding when copper is not used as the wire material is also determined by t ₀ ≈3 × δ, and when other materials are used. You can use this idea.

When the wire material is copper and the upper limit of the driving frequency is approximately 1 MHz, the skin depth δ = 66 at 1 MHz.
Since μ = 0.066 mm, it is about 0.2
It can be said that the optimum thickness is about mm.

Further, assuming that the upper limit of the driving frequency is approximately 5 MHz, the skin depth δ = 30 μ = 0.030 at 5 MHz.
Since the thickness is mm, it can be said that the optimum thickness is about 0.1 mm when tripled.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to FIGS. 9 (a) and 9 (b).

In the figure, reference numerals 15a and 15b denote thin plate punching coils. In this embodiment, the coils 15a and 15b formed by punching out a thin conductive plate are used as primary and secondary coils.
The laminated coil is constructed by using either one of the following windings.

As described above, according to the present embodiment, since the thin plate punching coils 15a and 15b are used for either one of the primary winding and the secondary winding, it is impossible to form a spiral winding by the winding method. Since a large current in a region can be handled, a unique effect that a wider range of electrical specifications can be dealt with can be obtained in addition to the effects of Examples 1 to 3 above.

(Embodiment 5) A fifth embodiment of the present invention will be described below with reference to FIGS.

In this embodiment, as shown in FIG. 10A, a thin conductive plate having substantially the same winding width as that of the primary windings 4a and 4b and the secondary winding 5 is used as the first turn coil 15a. It is inserted in at least one of the layers of the next winding, and as shown in the power supply circuit diagram of FIG. 10B, one lead end of the one-turn coil 15a is connected to the ground of the power supply circuit. One of the drawer ends is opened.
Here, the connection between one lead end and the power supply circuit does not have to be ground as long as it has a stable potential.

As described above, according to the present embodiment, the primary and secondary electrostatic shielding can be easily performed even in the stacking method, and a new effect that the noise reduction can be achieved is added to the effects of the first to fourth embodiments. Obtained.

The one-turn coil 15 used here
Regarding a, a printed coil formed by etching may be used.

(Sixth Embodiment) A sixth embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, the primary windings 4a, 4b and 2
A coil 2a obtained by spirally winding one layer of an electric wire having a rectangular cross-section having a self-bonding layer and an insulating coating layer and having a winding width substantially the same as that of the next winding 5 so as to be flat in the longitudinal direction of the electric wire cross-section. Is inserted into at least one of the layers of the primary and secondary windings, one lead end is connected to the stable potential of the power supply circuit, and the other lead end is opened.

As described above, according to the present embodiment, it is possible to form the electrostatic shielding coil in the same manufacturing process as that of the other spiral coils, and it is possible to obtain the unique effect of reducing the noise.
It is obtained in addition to the effect of 4.

(Embodiment 7) A seventh embodiment of the present invention will be described below with reference to FIGS. 12 (a) to 13 (b).

In the figure, 4a _R , 4b _R are right magnetic leg primary windings, 5 _R are right magnetic leg secondary windings, 4a _L , 4b _L are left magnetic leg primary windings, 5 _L are left magnetic legs. The leg secondary winding is shown.

In this embodiment, as shown in FIG. 12A, two sets of laminated coils of the present invention are used and a UU type magnetic core 1a is used.
Is incorporated in each laminated coil.

As an example of connection, FIG. 12 (b), (c),
As shown in FIGS. 13 (a) and 13 (b), there is a method of connecting the coils in series or in parallel, and a connection method other than this may be used.

As described above, according to this embodiment, the UU type magnetic core 1a is provided.
The abutting parts of are located in the laminated coil, that is, they have an inner iron structure, and it is possible to reduce noise interference to the external power supply circuit and equipment due to the leakage magnetic flux from the abutting parts. Further, in the case of a structure having a magnetic gap at the abutting portion of the UU-shaped magnetic core 1a, the magnetic gap has a divided gap structure that can be divided into two left and right magnetic legs, and an increase in coil loss due to leakage magnetic flux from the magnetic gap can be reduced. This new effect is obtained in addition to the effects of Examples 1 to 6.

(Embodiment 8) An eighth embodiment of the present invention will be described below with reference to FIG.

FIG. 14 is an external view of the spiral winding and the insulating paper showing the eighth embodiment of the present invention. Eighth of this embodiment
13 is applicable to the case where the left and right windings are connected in series as shown in the primary side connection diagram of FIG. 13 (a) or FIG. 13 (b). As shown in FIG. The spiral winding 2c is formed by continuously forming the windings to be inserted into the legs, which is continuously formed on the left and right sides.

According to the present embodiment, in addition to the effect of the seventh embodiment, it is not necessary to connect the left and right coils, so that there is a new effect that the man-hours for connecting the laminated coils can be reduced.

[0061]

INDUSTRIAL APPLICABILITY As described above, the present invention uses an electric wire having a self-bonding layer and an insulating coating layer and having a rectangular cross section, and is wound in a single layer so as to be flat in the longitudinal direction of the electric wire cross section. -Shaped single coil is used for at least one of the primary winding and the secondary winding so that all of the primary and secondary windings are one-layered and have substantially the same winding width and face to face. While alternately winding the windings of each layer, at least one of the primary winding and the secondary winding is divided, and the windings of each layer of the divided windings are connected in parallel or in series. Since the laminated coil is formed on the core and the magnetic core 1 forming the closed magnetic circuit is incorporated from the direction in which the coil is laminated, (1) the winding space factor can be improved.

(2) Low loss can be realized at high frequencies. (3) The thickness can be standardized, and variations in production and performance can be reduced.

(4) Since the surface pressure at the crossing portion of the lead-out portion with the winding can be reduced, the reliability is improved.

(5) A thin coil can be easily manufactured by the winding method. Further, in the case where the primary or secondary auxiliary winding is additionally formed with the same thickness as other spiral windings, (6) the step is not generated when the coils are laminated, so that the manufacturing quality is stable. .

(7) Since the coupling is stable, the control performance is also stable. Also, copper is used as the electric wire material for each layer, the upper limit of the driving frequency at the power source is f, δ is the skin thickness, and δ =
66.1 / √f (mm), the winding thickness t ₀ is 0.3 mm> t ₀
With ≈ 3 x δ (mm), (8) it is possible to significantly reduce the loss and effectively utilize the amount of wire material when assembling the transformer.

(9) Standardized optimum design is also possible. Further, in the case where the laminated coil is formed by using the coil formed by punching out the thin plate-shaped conductive plate for either one of the primary winding and the secondary winding, (10) it becomes possible to handle a large current, It can also support a wide range of electrical specifications.

Further, a thin plate-shaped conductive plate having substantially the same winding width as that of the primary winding and the secondary winding is inserted as at least one of the layers of the primary and secondary windings as a one-turn coil, and In a configuration in which one lead end of the turn coil is connected to the ground of the power supply circuit and the other lead end is open, (11) low noise can be achieved.

Also, an electric wire having a rectangular cross section with a self-bonding layer and an insulating coating layer and having substantially the same winding width as the primary winding and the secondary winding is flattened in the longitudinal direction of the cross sectional shape of the electric wire. Like
Insert a coil wound one layer in a spiral shape into at least one of the layers of the primary and secondary windings, connect one lead end to the stable potential of the power supply circuit, and open the other lead end. (12) The electrostatic shielding coil can be formed in the same manufacturing process as other spiral coils, thereby reducing the number of manufacturing steps and achieving low noise.

Further, in the case where two sets of laminated coils are used and the UU-shaped magnetic core 1a is incorporated in each laminated coil, (13) noise interference to the external power supply circuit and equipment can be reduced. .

(14) The loss of the coil due to the leakage magnetic flux from the magnetic gap can be reduced.

Further, in the structure in which the windings inserted in the left and right magnetic legs are continuously formed, (15) the number of steps for connecting the laminated coil can be reduced.

As described above, the present invention can inexpensively provide a thin transformer using a laminated coil which has low loss including quality including electric performance, is versatile, and can handle high frequency with low loss.

By using the thin transformer of the present invention in a power supply device, (16) it is possible to provide a power supply device which can be differentiated by cost and thinning. The great effect is produced, and the industrial value is extremely large.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of a laminated coil of a first embodiment which is an embodiment of a thin transformer of the present invention (b) the same connection diagram (c) the same connection diagram

FIG. 2 is a perspective view of a spiral coil which is a main part of the same.

FIG. 3A is a cross-sectional view of another embodiment of the laminated coil, which is the same part, as FIG. 3B, the same connection diagram, and FIG.

FIG. 4A is a cross-sectional view of another example of an electric wire having a rectangular cross-section that is the same main part. FIG. 4B is a cross-sectional view of another example of an electric wire that has a rectangular cross-section that is the main part.

5A is a sectional view of a laminated coil which is an essential part of the thin transformer of the second embodiment. FIG. 5B is a sectional view of a laminated coil which is an essential part of the thin transformer of the second embodiment. (C) Circuit diagram of a power supply circuit using the second embodiment

FIG. 6 is a sectional view of a laminated coil which is a main part of the third embodiment.

FIG. 7 is an explanatory diagram showing the relationship between frequency and AC resistance increase rate for explaining the cancellation effect.

FIG. 8 is a sectional view of a laminated coil, which is the main part of the same.

FIG. 9A is a plan view of a thin plate coil which is an essential part of the fourth embodiment. FIG. 9B is a plan view of a thin plate coil which is an essential part of the fourth embodiment.

FIG. 10A is a sectional view of a laminated coil which is a main part of the fifth embodiment; FIG. 10B is a connection diagram of a power supply circuit using the fifth embodiment.

FIG. 11 is a sectional view of a laminated coil which is an essential part of the sixth embodiment.

12A is a sectional view of the seventh embodiment, FIG. 12B is a connection diagram of the seventh embodiment, and FIG. 12C is a connection diagram of the seventh embodiment.

FIG. 13A is another connection diagram of the seventh embodiment. FIG. 13B is another connection diagram of the seventh embodiment.

FIG. 14 is a perspective view of a spiral winding and an insulating paper, which are essential parts of the eighth embodiment.

FIG. 15A is a cross-sectional view of a spiral laminated coil, which is a main part of a conventional thin transformer, and FIG. 15B is a circuit diagram of a power supply circuit using the thin transformer.

FIG. 16 is a sectional view of the same.

FIG. 17 is an exploded perspective view of the same.

[Explanation of symbols]

 1 magnetic core 1a UU type magnetic core 2 spiral winding 2a spiral winding using a rectangular wire 2b rectangular wire lead-out portion 2c left and right continuously forming spiral winding 3 insulating paper 4 primary winding 4a primary split winding 4b 1 Secondary split winding 5 Secondary winding 5a Secondary split winding 5b Secondary split winding 6 Tertiary winding 7 Input power supply

Claims (8)

[Claims] 1. A single coil in which an electric wire having a flat cross section having a self-fusing layer and further having an insulating coating layer is spirally formed by one layer so as to be flat in the longitudinal direction of the electric wire in cross section. It is used for at least one of the primary winding and the secondary winding.
Moreover, the windings of the respective layers are alternately laminated so as to face each other, and at least one of the primary winding and the secondary winding is divided into windings, and the windings of the respective layers of the divided windings are Form the laminated coil so that it becomes parallel or series connection,
A thin transformer incorporating a magnetic core forming a closed magnetic circuit from the direction in which the coils are stacked. 2. The thin transformer according to claim 1, wherein the primary or secondary auxiliary winding is additionally formed with the same thickness as that of the other spiral winding. 3. Copper is used as the electric wire material for each layer, and the upper limit value f of the driving frequency at the power source and the thickness (t ₀ ) of the winding are set to 0.3 mm> t ₀ ≈3 × δ (mm) (δ The thin transformer according to claim 1 or 2, wherein the skin thickness is δ = 66.1 / √f (mm) for copper. 4. A thin transformer according to claim 1, wherein a coil formed by punching out a thin conductive plate is used for either one of the primary and secondary windings. 5. A one-turn coil in which a thin plate-shaped conductive plate having substantially the same winding width as that of the primary and secondary windings is inserted as at least one of the layers of the primary and secondary windings as a one-turn coil. 4. One of the lead-out ends is connected to a stable potential of the power supply circuit, and the other lead-out end is opened.
Or the thin transformer described in 4. 6. An electric wire having a rectangular cross section, which has a winding width substantially the same as that of the primary and secondary windings, has a self-bonding layer, and has an insulating coating layer,
Make a spiral shape so that it becomes flat in the longitudinal direction of the cross section of the wire.
The coil wound in layers is inserted into at least one of the layers of the primary and secondary windings, one lead end is connected to a stable potential of a power supply circuit, and the other lead end is opened. The thin transformer according to 2 or 3 or 4. 7. The thin transformer according to claim 1, wherein two sets of laminated coils are used and a UU type magnetic core is incorporated in each laminated coil. 8. The thin transformer according to claim 7, wherein windings inserted in the left and right magnetic legs are continuously formed.