JPH0227546Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an E-type ferrite core for a small transformer.

Small transformers are flash discharge emitters for photography,
These transformers are used in many electrical and communication devices such as desk calculators and video tape recorders, and today, compact transformers whose length and width are reduced to about 8 to 10 mm are being proposed.

The present invention relates to a ferrite core for this type of small transformer, and the first purpose is to propose a ferrite core that can be flattened at the same time as the transformer form is miniaturized, and the second purpose is to reduce the transformer efficiency. The third objective is to propose a ferrite core suitable for mass production in order to make the transformer inexpensive.

Therefore, in the present invention, the central leg, left and right legs, and yoke are integrally formed of ferrite material, the yoke is a rectangular plate, and the left and right legs extending from each of the longitudinal ends of this yoke are the same as the yoke part. The center leg has a rectangular cross section with the long side in the left and right leg direction and the short side sufficiently smaller than the yoke width, and one side corresponding to the long side is one side corresponding to the long side of the yoke part and one side. In the E-shaped core for a small transformer, the center leg has four corners of a rectangular cross section cut out to form slopes, and the left and right legs are connected to one side of the yoke. A ferrite core for a small transformer is proposed, characterized in that the inner surfaces of the central leg are curved so as to be substantially parallel to the corner slope of the central leg, which is opposite to the leg forming one surface.

Note that the above-mentioned ferrite core can be used for either an E-E type transformer or an E-I type transformer.

The ferrite core configured as described above can be made smaller and flatter without reducing efficiency compared to conventional small transformers of this type, and the ferrite core can be easily produced. Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 is a perspective view of a small transformer using a ferrite core according to the present invention, and Figure 2 is A in Figure 1.
3 is a sectional view of the small transformer taken along line B-B in FIG. 2.

In these drawings, 1 and 2 are ferrite cores, 3 is a bobbin, 4 is a known coil, 5 is a terminal pin for fixing the end of the coil, and 6 is an insulating tape wrapped around the outer circumference of the coil 4.

As detailed in FIG. 4, the ferrite cores 1 and 2 are E-shaped cores with the same shape, and these cores are connected to the central leg 1.
a, 2a, left and right legs 1b, 1c, 2b, 2c, and yokes 1d, 2d are integrally formed of ferrite material.

As shown in the figure, the central legs 1a and 2a have a substantially rectangular cross section in the left and right direction, that is, with the long side in the horizontal direction and the short side in the vertical direction, and the thickness of the rectangular cross section (in the short side direction length) is sufficiently smaller than the width of the plate-shaped yokes 1d and 2d, and the lower surfaces of the central legs 1a and 2a are flush with the lower edges of the yokes 1d and 2d. The yokes 1d and 2d are made to protrude from the lower part of the inner surface. Note that the central legs 1a and 2a have a rectangular cross section.
It has a shape with two corners cut off, but the corners
The portions corresponding to R ₁ and R ₂ do not necessarily have to be removed.

As shown in the figure, the left legs 1b, 2b and the right legs 1c, 2c are formed to have the same width as the plate-shaped yokes 1d, 2d, and the cross-sectional shapes of these left and right legs are shown in FIGS. As can be seen from Figure 4, the upper half is curved and gradually becomes thicker. That is, the inner surfaces of the left and right legs 1b, 1c, 2b, and 2c are formed such that the distances between each position of the inner surfaces and the central legs 1a and 2a are approximately equal.

In addition, the cross-sectional area of each of the left and right legs 1b, 1c is designed to be 1/2 of the cross-sectional area of the center leg 1a.
Since each is designed in the same way, by curving the inner surfaces of the left and right legs as described above, the depth width of the ferrite cores 1 and 2 (the distance between the outer surfaces of the left and right legs) is reduced. It is advantageous to be able to do so.

Furthermore, when forming the inner surfaces of the left and right legs 1b, 1c, 2b, and 2c in a curved manner, it is preferable to form them as shown in FIG.

FIG. 5 is a partially enlarged sectional view of the ferrite core 1 cut in the same manner as in FIG. 3, and shows the right leg 1c, but the left leg 1b and the left and right legs 2b, 2c of the ferrite core 2 are formed in the same way.

That is, the curved surfaces P ₁ to _{P 2} illustrated are circular arcs centered on point O ₁ , the curved surfaces P ₃ to P ₄ are circular arcs centered on point O ₂ , and the curved surfaces P ₂ to _{P 3} are circular arcs centered on point O 2. is a straight line connecting the above two circular arcs.

If the inner surfaces of the left and right legs are formed in this manner, the distance from the center leg surface, that is, the distance from the center leg to each position on the inner surface becomes constant.

As shown in a perspective view in FIG. 4, the bobbin 3 described above includes a cylindrical portion 3a, flanges 3b and 3c provided at both ends of the cylindrical portion 3a, and a wall thickness below the flanges 3b and 3c. The terminal pin receiver 3d and 3e are integrally formed from a synthetic resin material.

The cylindrical part 3a is the central leg 1 of the ferrite cores 1 and 2.
It is a substantially rectangular cylinder that matches the terminal pin receivers 3d and 3e, and the notches provided in the terminal pin receivers 3d and 3e are aligned with the guide groove 3.
f, and the coil end is pulled out from this groove 3f and each terminal pin 5 planted in the terminal pin receivers 3d and 3e
to be fixed to.

The coil 4 described above is a well-known transformer coil, and a plurality of coils such as a primary coil, a secondary coil, or a tertiary coil are provided depending on the purpose.

When assembling the small transformer mentioned above,
First, the coil 4 is wound around the cylindrical part 3a of the bobbin 3.
are provided, and the coil ends are fixed to each terminal pin 5, and an insulating tape 6 is wrapped around the outer periphery of the coil 4. After that, the ferrite cores 1 and 2 are assembled by inserting the center legs 1a and 2a into the cylindrical part 3a of the bobbin 3, and the joint surfaces of the center legs 1a and 2a and the joints of the left and right legs 1b and 1c and 2b and 2c are assembled. Fix the surface using adhesive.

The small transformer mentioned above has ferrite cores 1 and 2.
The central legs 1a, 2a have a substantially rectangular cross section and protrude from the lower positions of the yokes 1d, 2d, and the inner surfaces of the left and right legs 1b, 1c, 2b, 2c extend along the outer periphery of the coil 4. The left and right legs are curved to increase the core thickness, so the left and right legs are taller than each other (core width).
Even if iron is restricted, iron deficiency will not occur. This allows the height of the transformer to be sufficiently shortened.

FIG. 6 shows an embodiment in which the upper and lower surfaces of the bobbin cylindrical portion 3a are formed thinner to further flatten the shape of the transformer.

Since the bobbin cylindrical portion 3a has an oblique side, the upper and lower sides can be made thinner, and the height of the transformer is effectively lowered by the thinner upper and lower sides. Note that the same effect can be obtained even if the upper and lower sides of the bobbin cylindrical portion 3a are cut off, but in this case, it is sufficient to wrap an insulating tape or the like around the cylindrical portion 3a before winding.

FIG. 7 shows an embodiment in which the inner surfaces of the left and right legs 1b, 1c, 2b, 2c are curved in a dogleg shape.

When carried out in this way, the inner surfaces of the left and right legs do not precisely follow the outer circumferential surface of the coil 4, so the height (core width) of the left and right legs becomes larger compared to the above-mentioned embodiments, and the transformer is adjusted accordingly. Although this increases the height, it is advantageous in that it facilitates the formation of the medial surfaces of the left and right legs.

As mentioned above, in the ferrite core according to the present invention, the central leg has a substantially rectangular cross section and is formed to protrude from the bottom of the yoke, and the corner of the central leg is cut off to form a slope, which is approximately parallel to the slope. Since the inner surfaces of the left and right legs are curved so as to be curved, it is possible to provide a flat, compact transformer whose height is as short as possible.

Moreover, according to the above-described structure of the ferrite core, it is possible to equip the transformer with an equivalent coil without reducing the amount of iron core compared to conventional products, resulting in a compact transformer that does not reduce efficiency and is easy to produce.

In addition, in the above-described present invention, a small transformer using the bobbin 3 has been described, but depending on the use of the transformer, the wire may be wound directly on the central leg.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of a small transformer using a ferrite core according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 2 is a cross-sectional view of the small transformer taken along line B-B in Figure 2, Figure 4 is an exploded perspective view of the ferrite core and bobbin, Figure 5 is a partially enlarged sectional view of the ferrite core, and Figure 6 is and FIG. 7 are sectional views similar to FIG. 3 showing another embodiment. 1, 2...Ferrite core, 1a, 2a...Central leg, 1b, 2b...Left leg, 1c, 2c...Right leg, 1d, 2d...Yoke, 3...Bobbin, 4...
...Coil, 5...Terminal pin.

Claims (1)

[Scope of utility model registration request] The center leg, the left and right legs, and the yoke are integrally formed of ferrite material. has a rectangular cross section with the long side in the left and right leg direction and the short side sufficiently smaller than the yoke width, and one side corresponding to the long side is flush with one side corresponding to the long side of the yoke part. In the E-shaped core for a transformer, the central leg has four corners of a rectangular cross section cut out to form sloped corners, and the left and right legs are opposite to the side that forms one side of the yoke. A ferrite core for a small transformer, characterized in that the inner surface of the central leg is curved so as to be substantially parallel to the corner slope of the central leg.