Delay Line

Abstract

A delay line comprising a first magnetic core of planar type, an inductance coil wound along the length of the planar magnetic core, a second magnetic core also of planar configuration applied on the first magnetic core in an overlying relationship, and several recessed portions provided either on the inner surfaces of said first and second magnetic cores facing the inductance coil or on the outer surfaces of the first and second magnetic cores at spaced apart positions or intermediate between coil sections when the inductance coil has been split into a number of coil sections.

Description

BACKGROUND OF INVENTION

This invention relates generally to delay lines, and more particularly to a type of delay line consisting of planar magnetic substances and employed in electronic computers, television receivers, and the like.

Heretofore, a type of delay line which comprises an inductance coil wound on a sheet of magnetic substance or core such as a ferrite core has been widely known. This type of delay line has a construction generally indicated in FIG. 2A, which will be described later in more detail. In such a construction, a sheet of planar magnetic core 1 consisting of, for instance, a ferrite core is provided with a plurality of coil sections 2 wound thereon so that the individual sections are spaced apart from each other with constant spacing.

In an overlying relation to these coil sections 2, an outer magnetic substance 3, also of a planar shape, is placed on the planar magnetic core 1. The distribution of the magnetic lines in these magnetic substances 1 and 3 is as indicated by dotted lines arrow in the same drawing.

With the above described construction of the delay line, the magnetic lines of forces corresponding to a higher frequency input signal applied across these coils tend to collect in the part of the magnetic paths near the coil sections as indicated by a, while the magnetic lines of forces corresponding to a lower frequency portion of the input signal tend to be extended in a wider region of the magnetic paths as indicated by both of a and b.

As a result, one part of the magnetic lines of forces corresponding to lower frequencies is interlinked with the adjacent coil sections, and the inductance of these coil sections corresponding to the lower frequencies will be increased, resulting in an increase in the delay time of the delay line. This means that the delay time of the delay line is caused to be shorter in the higher frequency range of the input signal than that for the lower frequency range, and for this reason, the delay characteristics of this type of the conventional delay line have been impaired.

For the purpose of eliminating the above described drawback, countermeasures such as reducing the thickness of the magnetic substances or reducing the magnetic permeability thereof have been proposed. However, such a measure requires ever thinner thickness or even low magnetic permeability of the magnetic substances if the frequency range of the input signal applied to the delay line is to be elevated.

Furthermore, in the above-described construction of the delay line, the distribution of the magnetic lines of forces within each of the inductance coil sections 2 has also been varied in accordance with the frequencies in the input signal. More specifically, the magnetic lines of forces corresponding to a still higher frequency portion of the input signal tend to be confined in smaller loops, as indicated by dotted lines a in FIG. 6A and will be explained hereinafter in more detail, encircling around merely fractional portions of respective individual coil sections, and the magnetic lines of forces corresponding to a middle portion of the frequencies contained in the input signal tend to be extended a little more around the individual coil sections as indicated by dotted lines b in FIG. 6A.

Since the inductance corresponding to the distribution of the magnetic lines of forces indicated by the dotted lines a is less then that corresponding to the dotted line b, the delay time of the delay line is shortened in the higher frequency range, whereby the delay characteristics of the delay line have also been impaired.

SUMMARY OF THE INVENTION

Therefore, the primary object of the present invention is to provide an improved construction of delay lines whereby all of the shortcomings of the conventional construction are substantially eliminated.

Another object of the present invention is to provide an improved construction of the delay line wherein the delay characteristics for an input signal which contains various frequencies ranging from a comparatively lower frequency to an extremely higher frequency can be maintained substantially constant.

Still another object of the present invention is to provide an improved construction of delay lines, wherein thinning of the magnetic substances or reduction of the magnetic permeability thereof as in the case of the conventional construction is not required.

These and other objects of the present invention can be achieved by an improved construction of the delay line of the type comprising a first magnetic core of planar shape, an inductance coil wound along the length of the planar magnetic core, and a second planar magnetic core applied on the outside of the first planar magnetic core on which the inductance coil is wound, in which the improvement resides in a plurality of recessed portions provided on one or both of the magnetic cores for the purpose of restricting the magnetic paths between any two adjacent coils.

In another aspect of the invention, either on the inside surface of said outer magnetic substance or on the inside surface of the first magnetic core, at positions where the split sections of the coil are wound, recessed portions are formed for the purpose of preventing formation of small loops of magnetic paths for a high-frequency region of the input signal, whereby the characteristic feature of the magnetic substances can be effectively utilized, and the high-frequency characteristics of the delay line is much improved.

The nature, principle, and the utility of the present invention will be more clearly understood from the following detailed description when read in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF DRAWING

In the drawing:

FIG. 1 is a sectional view of a delay line which constitutes one embodiment of the present invention;

FIGS. 2A, 2B, 2C, and 2D are sectional explanatory diagrams showing the distribution of magnetic lines of forces created by various frequency components included in the input signal;

FIG. 3 is a sectional view of a delay line constituting a modification of the first example shown in FIG. 1;

FIG. 4 is a sectional view of a delay line constituting another modification of the first example;

FIG. 5 is a sectional view of a delay line according to another embodiment of the invention;

FIGS. 6A and 6B are sectional explanatory diagrams showing the distributions of magnetic lines of forces corresponding to still higher and middle frequency components; and

FIGS. 7 and 8 are sectional views respectively indicating modified forms of the second embodiment of the present invention shown in FIG. 5.

DETAILED DESCRIPTION

The principle of the present invention will now be explained in more detail. As described in the forward part of this description, the magnetic lines of forces in the magnetic substances 1 and 3 in this type of delay line are divided into two groups as designated by a and b in FIG. 2A, respectively.

Magnetic lines of forces corresponding to higher frequency components in the input signal of the delay line have a tendency to collect in a region nearer to the individual, split wound coils, as indicated by a, while the magnetic lines of forces corresponding to lower frequency components in the input signal of the delay line have a tendency to be distributed in wider regions in the magnetic substances 1 and 3 as indicated by both a and b. It will be clearly apparent from FIG. 2A that the magnetic lines of forces belonging to the group designated by b are partly interlinked with the immediately adjacent coils.

In this case, if the plurality of semicircular recesses 4 and 5 are cut out on the outer surfaces of the magnetic substances 1 and 3, respectively, as is best been in FIG. 1, indicating a preferred embodiment of the present invention, the distribution of the magnetic lines of forces corresponding to lower frequency components in the input signal will be changed as indicated by b.sub.1 in FIG. 2B, while the distribution of the magnetic lines of forces for higher frequency components is kept unchanged, whereby the interlinking of the magnetic lines of force with the immediately adjacent coils in the former case is interrupted by the recessed portions 4 and 5, and the delay characteristics of the delay line will be much improved.

The above described feature will now be described in more detail. The distribution of the magnetic lines of force corresponding to lower frequency, in the case where the above described semicircular recesses 4 and 5 are provided, as shown in FIG. 2C, are indicated by dotted lines b.sub.2. However, since it is difficult for the magnetic lines of forces to follow such a rather complicated magnetic path, more practicable paths of the magnetic lines of forces will be as shown in FIG. 2D.

Since in the distribution of FIG. 2D, inner paths c interlinking with the immediately adjacent coils might be assumed, such a distribution will not be practicable when it is considered that the magnetic lines of forces should follow a path whose magnetic reluctance is reduced to a minimum, and that magnetic fluxes for the same current corresponding to a certain frequency cannot intersect each other. For this reason, the actual distribution of the magnetic lines of forces will be such that the magnetic lines of forces b1 in FIG. 2D are pushed aside by a small amount by the lines of forces a, whereby the resultant distribution of the magnetic lines of forces will be as represented by a and b.sub.1 in FIG. 2B.

In consideration of the thickness of the magnetic core 1 with which the above described advantageous effect can be obtained, if it is desired to obtain a similar effect as indicated by FIG. 2B by the conventional construction shown in FIG. 2A, the thickness d.sub.1 of the magnetic substance 1 in the conventional construction should be thinner than the inside thickness d.sub.2 at the bottom portion of the recesses 4. Such a reduced thickness of the magnetic substance 1 not only decreases the inductance for the lower frequency portion but also sacrifices the inductance for the higher frequency portion of the input signal.

When the effect of the recesses 4 and 5 is considered from the viewpoint of magnetic permeability, since such an effect is more significant when the magnetic permeability of the magnetic substances is high, the magnetic substances of higher permeability is preferably provided the available range in the magnetic characteristic thereof extends to the frequency range of the delay line.

Furthermore, as briefly described hereinbefore, the magnetic lines of forces corresponding to a still higher frequency portion of the input signal form small loops, which encircle merely a fractional portion of the respective individual coil sections 2 as indicated by dotted lines a schematically indicated in FIG. 6A, and the magnetic lines of force corresponding to a middle portion of the frequencies in the input signal encircle each of the individual coil sections 2 as indicated by dotted lines b in the same drawing. Such a distribution of the magnetic lines of force impairs the frequency characteristic of the delay line as described before.

An improved construction of the delay line constituting an embodiment of the present invention is indicated in FIG. 1, and another improved construction thereof in accordance with another aspect of the present invention is indicated in FIG. 5.

In the delay line shown in FIG. 1, there is also employed a magnetic substance or core 1 of a planar configuration, around which a plurality of coil sections 2 are wound in a split manner, a constant being maintained between each of the coil sections 2. An outer magnetic substance or core 3 is applied on the above described magnetic core 1 in an overlying manner. The cores 1 and 3 are provided on the outer surfaces thereof with recessed portions 4 and 5 of semicircular configuration. The recessed portions are positioned at intermediate points between adjacent coil sections 2, the recessed portions 4 and 5 semicircular configuration at each of these points being disposed back-to-back. A grounding electrode 6 and a dielectric material 7 are provided in laminar disposition on the side of the core 1 remote from the core 3. With the above described construction, as is widely known, the stray capacitances between the coil sections 2 and the grounding electrode 6 are utilized as the required capacitances for the delay line.

The provision of the recessed portions at intermediate points between the coil sections 2 substantially eliminates the portions of the magnetic lines of forces interlinking two adjacent coil sections, whereby the high-frequency characteristic of the delay line can be remarkably improved.

FIG. 3 indicates a modification of the delay line described above with reference to FIG. 1, in which modification a required number of recesses 8a separated by lands 8b and each having a suitable width and depth are provided on one side (i.e., the side on which the outer magnetic substance is applied) of the magnetic core 1, the above described coil sections 2 being wound respectively in these recesses 8a , and recesses 4 and 5 corresponding to the recessed portions in the above-described example are formed on the outer surfaces of the magnetic cores 1 and 3 so that the section of each recess is of the shape of a slit having a narrow width. With such a construction, the inductance for each section of the coil 2 can be elevated because of the sufficiently low reluctance path provided for each of the coil sections.

In still another modification of the delay line shown in FIG. 1 which is shown in FIG. 4, the coil 2 is wound on the magnetic core 1 continuously, and the recessed portions 4 and 5 are formed with a trapezoidal configuration. Although the coil 2 in this case is wound continuously, the distribution of the magnetic lines of force can be substantially similar to that of FIG. 2B because of the existence of the recessed portions 4 and 5. All of the reference numerals in FIGS. 3 and 4 other than those referred to above designate members similar to those in the preceding example.

FIG. 5 shows still another example of the delay line organized in accordance with another aspect of the present invention.

In this embodiment of the invention, a plurality of coil sections 2 are split wound on an inner magnetic core 1 of a planar configuration, and an outer magnetic core 3 is applied on this wound inner magnetic core 1 in an overlying manner. A plurality of recessed portions 4 are provided on the inner surface of the outer magnetic core 3 at positions corresponding to sections S.sub.1, S.sub.2, S.sub.3,..... on which the plurality of coil sections 2 are wound on the inner magnetic core 1. By the provision of the recessed portions 4, creation of the small loops of the magnetic lines of force as represented by dotted lines a in FIG. 6A can be eliminated. A layer of a dielectric substance 5 and a grounding electrode 6 are provided between the inner magnetic core 1 and the coil sections.

Because of the existence of the recessed portions 4, the magnetic lines of force corresponding to higher frequencies follow paths as indicated by dotted lines a.sub.1 in FIG. 6B, whereby an inductance equivalent to that for middle frequencies can be obtained, and the high-frequency characteristic of the delay line is improved.

In FIG. 5, a construction having recessed portions 4 on the inner surface of the outer magnetic core 3 is illustrated, but it is possible, of course, to provide the recessed portions also on the inner magnetic core 1. FIG. 7 illustrates such a modification of the example of FIG. 5, in which modification the recessed portions 4 are provided on both the inner magnetic core 1 and the outer magnetic core 3.

In the case where the recessed portions 4 are provided on the surface of of the inner magnetic core 1 on which the above described sections of coils are wound, an adequate procedure such as limiting the recessed portions only in the longitudinally extending central portion of the magnetic core 1 so that the lateral edge portions thereof are left as they were can be followed. The coil sections 2 wound on the inner magnetic core 1 can then be supported by the lateral edge portions.

In the example shown in FIG. 7, a plurality of recessed portions are provided at intermediate positions between adjacent coil sections 2 as described in the first embodiment of the present invention shown in FIG. 1, although the shape of the recessed portions in the case is changed to a trapezoidal configuration. By the provision of the recessed portions 7, the low-frequency characteristic of the delay line can be improved as described in the first embodiment of the present invention.

Although it is not illustrated in the drawing, two of the outer magnetic substances as indicated in FIG. 5 by reference numeral 3 may be disposed on both sides of the inner magnetic core 1, and in this case, the recessed portions 4 may be provided on the inside surfaces of the two outer magnetic substances.

In the above described examples of the delay line, the coil 2 has been described as being split into a plurality of sections. However, the coil 2 may also be wound on the magnetic core 1 continuously as shown in FIG. 8, and the recessed portions 4 may be provided in a spaced-apart relationship, whereby substantially similar characteristics of the delay line as in the above described examples of the invention can be likewise obtained.

While in the delay line according to the present invention, distributed capacitances are used between the coil 2 and the grounded electrode 6, it is apparent that the principle of the present invention may also be applied to delay lines of concentrated constant type.

Furthermore, although all of the recessed portions for preventing interlinking with adjacent coil sections for lower frequencies have been described as provided on both of the first and second magnetic cores on the outer surfaces thereof, it is possible, of course, to provide the recessed portions on either one of the magnetic cores.

Claims

We claim:

1. In a delay line comprising a first magnetic core of planar type, an inductance coil wound around said planar magnetic core and comprising a plurality of coil sections disposed along said first magnetic core, a second planar magnetic core disposed on said first planar magnetic core in an overlying relationship, an improvement wherein a plurality of transversely disposed recessed portions are provided on at least one surface of at least one of said magnetic cores between sections of said coil, said recessed portions locally reducing the thickness of the core in which they are provided to restrict the magnetic paths between coil sections.

2. A delay line as defined in claim 1 wherein said inductance coil is of split type divided into a plurality of spaced apart coil sections, and said plurality of recessed portions magnetic provided on both of the two magnetic cores at positions respectively intermediate between adjacent spaced coil sections.

3. A delay line as defined in claim 1 wherein said inductance coil is of split type divided into a plurality of spaced apart coil sections, and said plurality of recessed portions are provided on one of said first and second magnetic cores at positions respectively intermediate between adjacent spaced coil sections.

4. A delay line as defined in claim 1 wherein said inductance coil is of continuous type distributed along said first planar magnetic core.

5. A delay line as defined in claim 2 wherein said plurality of recessed portions are provided on the outer surfaces of both of said two magnetic cores at positions respectively intermediate between adjacent coil sections.

6. A delay line as defined in claim 1 wherein said inductance coil is formed as a split type consisting of a plurality of spaced-apart coil sections, and said plurality of recessed portions are provided in a recessed form on the inner surface of said second planar magnetic core at positions facing respective coil sections.

7. A delay line as defined in claim 1 wherein said inductance coil is formed as a split type consisting of a plurality of spaced-apart coil sections, and said plurality of recessed portions are provided on the inner surface of said second magnetic core and also on the inner surface of said first magnetic core in such a manner that the recessed portions are disposed in a recessed configuration at positions respectively facing said coil sections.

8. A delay line as defined in claim 1 wherein said inductance coil is distributed continuously along said first magnetic core, and said plurality of recessed portions are provided on the inner surface of said second magnetic core in a spaced-apart relationship and with a recessed configuration.

9. A delay line as defined in claim 1 wherein the inductance coil is split into a plurality of spaced-apart coil sections, and said plurality of recessed portions are formed, as one part thereof with recessed configuration and provided on the inner surfaces of both of the magnetic cores at positions respectively facing said plurality of coil sections, and, as another part thereof, with a plurality of recesses formed on the outer surfaces of both of said magnetic cores respectively at positions intermediate between adjacent coil sections.

10. A delay line as defined in claim 1 wherein the inductance coil is split into a plurality of spaced-apart coil sections, and said plurality of recessed portions are formed, as one part thereof, with recessed configuration provided on the inner surface of said first magnetic core at positions respectively facing said plurality of coil sections, and, as another part thereof, with a plurality of recesses formed on the outer surfaces of both of said magnetic cores at positions respectively intermediate between adjacent coil sections.

11. A delay line as defined in claim 4 wherein a grounded layer and a dielectric layer are further provided on the outer surface of said first magnetic core.

12. A delay line as defined in claim 1, wherein portions of said coil are disposed between said first magnetic core and said second magnetic core.