JPH0341701A - Coil - Google Patents

Abstract

PURPOSE:To decrease a stray capacity and to improve a self-resonance frequency by winding the part of many turns at the beginning side of the winding of a conductor in a single layer or many layers at a small-diameter part, and winding the part of few turns at the finishing part of the winding of the conductor in a single layer at a large-diameter part. CONSTITUTION:A coil 1 has an aligned winding structure wherein a conductor 3 is wound around a core 2 by many turns. The shape of the longitudinal cross section of the core around which the conductor 3 is wound is formed continuously so that the small diameter part 4 and a large-diameter part 5 are alternately arranged to each other through a step part. The part of many turns (first turn - tenth turn) at the beginning side of the winding wherein the potential difference between the wires is large and the part of few turns (eleventh turn - fifteenth turn) at the side of the finishing side of the winding are separately wound around the small-diameter part and the large-diameter part which are formed in a core or bobbin shape, respectively. Therefore, the increase in stray capacity in the coil 1 is prevented, and the self-resonance frequency is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a coil, and more particularly to the shape of its core or bobbin and the winding structure of a conducting wire.

<Conventional technology> Conventionally, in various coils and flyback transformers, there has been an alignment method that allows effective use of the winding space of the core and allows the conductor to be wound the largest number of turns. The same structure is commonly used for conducting wires, called windings.

Note that aligned winding here refers to winding made by winding a conductor from one end of a core etc. to the other end, and then winding the conductor back from the other end of the wound conductor to the original one end. This is a structure in which the required number of layers can be stacked by repeating this process. In particular, a coil made by winding a single layer of conductive wire in an aligned manner around a core has the advantage that the overall stray capacitance (distributed capacitance) is minimized because the potential difference between each turn of the S wire is small. It is known that there is.

<Problems to be Solved by the Invention> However, as in the coil 1O shown in the cross-sectional view of FIG. (In the figure, when a two-layer aligned winding structure is adopted, the first turn on the winding start side and the 15th turn on the winding end side, where the line-to-line potential difference in the wound conductor 12 is the largest, are mutually connected to each other. As a result of being placed close to each other, the stray capacitance of the coil 10 increases rapidly.As the stray capacitance increases, the self-resonant frequency of the coil 10 decreases, making it difficult to use the coil 10 in high frequency ranges. This has resulted in the disadvantage that the range is limited, which means that it cannot be used as a coil unless it is within a frequency range below the self-resonant frequency.

The present invention was devised in view of such conventional disadvantages, and provides a coil that can reduce stray capacitance and increase the self-resonant frequency, thereby expanding the range of use in the high frequency region. It is an object.

<Means for Solving the Problems> In order to achieve the above object, the coil according to the present invention continuously forms a small diameter portion and a large diameter portion on the core or bobbin around which the conductive wire is wound, and A large number of turns on the winding start side of the conductor wire are wound in a single layer or multilayer around the small diameter part, and a few turns on the winding end side of the conductor wire are wound in a single layer around the large diameter part. This is a characteristic feature.

According to the above configuration, even if the winding structure of the conductive wire constituting the coil is multi-layered as a whole, a large number of turns at the start of winding and a few turns at the end, where the potential difference between the wires is large, are separated. Since it is separated into a small diameter part and a large diameter part formed on the core or bobbin and then wound,
The stray capacitance of the coil will be reduced.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a cross-sectional view showing a schematic configuration of a coil according to the present invention, and reference numeral 1 in this figure indicates a coil. This coil 1 has an aligned winding structure in which the conducting wire 3 is wound around the core 2 many times (15 turns in the figure), and the longitudinal cross-sectional shape of the core 2 around which the conducting wire 3 is wound is The small diameter portion 4 and the large diameter portion 5 are formed in a continuous manner with a step between them. Note that the shape of the large diameter portion 5 may be, for example, tapered toward the small diameter portion 4.

A large number of turns on the winding start side of the coil 1, that is, from the first turn to the eighth turn, are wound in alignment with respect to the small diameter portion 4 of the core 2 from one end to the other end. The conductor wire is wound as the first layer, and the conductor &! The 9th turn and the 10th turn of No. 3 are wound back as the second layer. Further, a small number of turns on the winding end side of the conductive wire 3, that is, from the 11th turn to the 15th turn, are wound in a single layer around the large diameter portion 5 of the core 2 in an aligned manner.

In the above description, it is assumed that 15 turns of the conductor VA3 are wound around the core 2 of the coil 1, but this number of turns can be arbitrarily set as necessary, for example. It goes without saying that there is no problem even if the conducting wire 3 wound around the small diameter portion 4 of the core 2 is a single layer.

Therefore, in this coil 1, a large number of turns (1st turn to 1st O turn) on the winding start side where the line potential difference is large
minutes and a small number of turns on the winding end side (11th turn to 15th turn)
Since the coil 1 is wound separately in the small diameter part and the large diameter part formed on the core or bobbin, the stray capacitance of the coil 1 increases compared to the coil 10 shown as a conventional example. This causes the self-resonant frequency to rise.

By the way, the inventor of the present invention conducted an experiment to compare the characteristics of the coil 1.10 according to the present invention and the conventional example, and as is clear from FIG. 3 showing the experimental results, the conventional multilayer coil Compared to the coil 10 having an aligned winding structure,
It has been confirmed that the stray capacitance of the coil 1 having a multi-layered winding structure according to the present invention is reduced regardless of the number of turns of the conductor 3 formed in the core 2. In this figure, the vertical axis represents the stray capacitance, and the horizontal axis represents the conductor 3 wound around the core 2, with the number of turns per layer being 8.
In addition, the solid line in the figure shows the experimental results for the coil 1 according to the present invention, and the broken line shows the experimental results for the coil 10 according to the conventional example.

<Effects of the Invention> As explained above, in the coil according to the present invention, a small diameter portion and a large diameter portion are continuously formed on the core or bobbin around which the m-wire is wound, and the A large number of turns on the winding start side of the conducting wire are wound in a single layer or in multiple layers, while a small number of turns on the winding end side of the conducting wire are wound in a single layer around the large diameter portion. Therefore, even if the overall winding structure of the conducting wire constituting the coil is multi-layered, a large number of turns at the start of the winding and a few turns at the end, where the potential difference between the wires becomes large, are formed on the core or bobbin. Since the small diameter portion and the large diameter portion are separated and wound, the stray capacitance of the coil is reduced. As a result, the self-resonant frequency of the coil becomes higher than that of the conventional example, making it possible to expand the range of use of the coil in a high frequency region.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a coil according to the present invention, FIG. 2 is a sectional view showing a schematic configuration of a conventional coil, and FIG. 3 is an explanatory diagram showing experimental results of characteristics. . In the figure, numeral 1 is a coil, 2 is a core (bobbin), 3 is a conductor, 4 is a small diameter portion, and 5 is a large diameter portion.

Claims (1)

[Claims] (1) A small-diameter portion and a large-diameter portion are continuously formed on the core or bobbin around which the conductor is wound, and a large number of turns on the winding start side of the conductor are wound around the small-diameter portion in a single layer or in multiple layers. . A coil characterized in that a small number of turns on the winding end side of the conductive wire are wound in a single layer around the large diameter portion.