US3344384A - Temperature stable tubular element for inductive devices - Google Patents

Description

Sept. 26, 1967 R. 1.. HATTON 3,344,384

TEMPERATURE STABLE TUBULAR ELEMENT FOR INDUCTIVE DEVICES Filed May 5,. 1965 INVENTOR.

RICHARD l HATTON. BY-

ATT'YS United States Patent 3,344,384 TEMPERATURE STABLE TUBULAR ELEMENT FOR INDUCTIVE DEVICES Richard L. Hatton, Elmhurst, Ill., assignor to Resinite Corporation, Wheeling, Ill. Filed May 5, 1965, Ser. No. 453,423 4 Claims. (Cl. 336-179) This invention relates to a tubular element and, more particularly, to a sleeve-like member useful in connection with electronic gear as an inductance.

The problem of dimensional stability under varying temperatures is particularly acute in electronic instruments, especially inductances whose value is determined by their dimensions. Since these elements are used in large quantity, it is important that they be constructed as economically as possible. In the past, these two objectives; quality performance and economical manufacture have not been achieved. The provision of the portion of an inductor which achieves these twin objectives thus constitutes a specific objective of the invention.

A more generalized object of the invention is to provide a thermally stable tubular element which is adapted for use in a variety of installations where ambient temperatures vary such as the voice coil of a speaker.

A more specific object of the invention is to provide a thermally stable sleeve constructed of spirally wound layers of metal foil ribbons and ethylene terephthalate ribbons which is resilient and which is characterized by dimensional stability in operation as an inductor part so as to minimize frequency drift.

Other objects and advantages of the invention may be seen in the details of construction and operation set down in this specification.

The invention is described in conjunction with an illustrative embodiment of the accompanying drawing, in which:

FIG. 1 is a perspective view, partially broken away, of a channel selector element of a television set;

FIG. 2 is an enlarged fragmentary perspective view of one of the channel coils or inductances provided as part of the channel selector of FIG. 1;

FIG. 3 is a perspective view of the inventive sleeve shown with a tuning screw partially received therein;

FIG. 4 is a fragmentary perspective view of a tube embodying the teachings of the invention and in an intermediate stage of manufacture;

FIG. 5 is a view similar to FIG. 4 but on an enlarged scale and showing the inventive tube at a subsequent, but still intermediate stage of manufacture;

FIG. 6 is a perspective view of the inventive tube in its completed form and prior to insertion in the tuning coil form of FIG. 2;

FIG. 7 is an enlarged end view of the construction seen in FIG. 6;

FIG. 8 is a fragmentary sectional view such as would be seen along the sight line 8-8 applied to FIG. 6; and

FIG. 9 is an exploded perspective view of the invention used in a slightly different operating environment.

In the illustration given and with particular reference to FIG. 1, the numeral 10 designates generally a channel selector element of a television set and includes a U- shaped frame 11 equipped with front and rear upstanding walls 12 and 13, respectively. Rotatably mounted in the frame 11, by virtue of extending through the front rear walls, is a shaft 14 having fixed thereto turret plates 15 and 16. Each of the plates 15 and 16 is notched so as to receive a plurality of tuning coils such as is exemplified by the numeral 17. For this purpose, each tuning coil 17 is equipped with a plurality of windings (see FIG. 2) where different windings are designated 3,344,384 Patented Sept. 26, 1967 19 operating through a gear linkage 20, effective to ad vance or retract the tuning screw 18. Thus, the inductance of the tuning coil 17 is thus varied by the degree to which the tuning screw 18 is advanced or retracted within the hollow interior of the coil 17.

The invention here has to do with the sleeve-like member 21 which is inserted within the bore of the tuning coil 17 and which threadably receives the tuning screw 18 (see FIG. 3). The sleeve 21 is adhesively mounted within the bore by means of a polyester coating adhesive.

In television sets, it is necessary for the tuning elements to withstand, without dimensional deformation, temperatures of the order of -90 C. Heretofore, the female thread-providing elements have not been dimensionally stable so that the tuning screw 18 has had the tendency not to remain anchored properly in place, and thus, destroy the preset, fine tuning.

I find that this undesirable situation can be avoided through a uniquely constructed sleeve and the character of the sleeve construction can be most readily appreciated from a consideration of FIG. 8.

The, tube fragment 21 in FIG. 8 is seen to include as an innermost layer a relatively thick layer 22 of ethylene terephthalate. Proceeding outwardly from the layer 22, I provide a first layer of metal foil 23 of the order of 0.00075-0.00125" which advantageously may be of electrolytic copper. Thereafter, a similar thickness or second layer of metal foil 24 is provided after which I provide two layers 25 and 26 of ethylene terephthalate. Each of the layers is spirally wound relative to the axis of the tubular element 21 and are adhesively united by means of a polyester coating adhesive such as Type A of National Bronze Powder Co. A greater or lesser number of layers may be used, depending upon the installation, but it is advantageous to sandwich the spirally wound metal layer between outer layers of spirally wound ethylene terephthalate. For the particular application involved, the layers identified in FIG. 8 have the following thicknesses.

i; Element: Thickness, inch 22 0.005 23 0.001 24 0.001 25 0.003 26 0.001

The construction thus described is initially provided in the form of an elongated tube such as is designated 27 in FIG. 4. Depending upon the particular winding equipment used, the length of the tube 27 may be upwards of several feet in length. Thereafter, a transverse severing operation is performed such as is indicated schematically by the arrows 28 applied to FIG. 4 and which results in the intermediate tube designated 29 and seen in enlarged form (relative to FIG. 4) in FIG. 5. Thereafter, I subject the tube 29 to an indenting operation to provide three rows of indentations or recesses 30 in the sidewall of the tube 29 to result in the final construction seen in FIGS. 6 and 7.

In operation, the tubular element 21 is slidably inserted Within the hollow core of the tuning coil element 17 after which the tuning screw 18 is threadably received therein. The indentations 30 yield against the advance of the threads provided on the metal screw 18 so that the screw 18 may be bottomed as against the shoulder 17c (see FIG. 2) without damage to the element 21. Further, the tuning screw 18 may be retracted until it abuts the end wall 11 and continued rotation of the hollow shaft 19 permits the tuning screw 18 to be continually rotated again without damage to the sleeve 21. The provision for continued rotation of the tuning screw 18 in either direction is necessary since television sets are often operated by children who would continue turning a knob even though a stop has been reached. This safeguard can be realized Without stripping the threads in the female thread-providing member and further while maintaining the desirable dimensional stability with temperature change-as would occur between the time a set is first turned on and after it has been in operation for several minutes, or hours.

I find that through the use of the inventive element, it is unnecessary to go to expensive and carefully wrought tuning screws 18--for example, relatively inexpensive aluminum screws may be used in place of the previously employed brass screws.

A variety of metal foil ribbon may be employed for the development of the intermediate layer or layers in the element 21 such as nickel silver, electrolytic copper as previously mentioned, and cartridge brass.

In FIG. 9, the numeral 121 designates the inventive tube which is embossed with thread-like depressions at 130. Received within the laminated tube 121 is a ferrite core 118. The tube 118 is press fitted within a metal body 117 which is equipped with a cooperative cap portion 117a. Housed Within the body 117 and cover portion 117a is a coil 117b mounted on a flange-equipped bobbin 117C. The entire assembly constitutes a shielded transformer with leads as at 117d and 1170 for use in communications equipmentthe sleeve 121 providing a sure mounting for the core 118.

While in the foregoing specification, a detailed description of an embodiment of the invention has been set down for the purpose of illustration, many variations in the details herein given may be made by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. A temperature stable tubular element suitable as a component of an inductance comprising inner, intermediate, and outer layers of spirally arranged adhesively united ribbons, each layer including at least one ribbon spirally wound relative to the tubular element axis, said inner and outer layers being constructed of ethylene terephthalate, said intermediate layer being constructed of a metal foil, and a male-threaded part positionably received within said element for varying said inductance.

2. The structure of claim 1 in which said element is equipped with a plurality of axially spaced indentations to position said male-threaded part.

3. The structure of claim 1 in which said intermediate layer is constructed of copper foil.

4. The structure of claim 1 in which said intermediate layer includes a plurality of metal foils spirally wound and of a total thickness less than the thickness of the inner and outer layers.

References Cited UNITED STATES PATENTS 3,130,256 4/1964 Mildner 174107 X 3,233,036 2/1966 Jachimowi-cz 174-120 X FOREIGN PATENTS 886,888 1/1962 Great Britain.

LEWIS H. MYERS, Primary Examiner.

C. TORRES, T. I. KOZMA, Assistant Examiners.

Claims (1)

1. A TEMPERATURE STABLE TUBULAR ELEMENT SUITABLE AS A COMPONENT OF AN INDUCTANCE COMPRISING INNER, INTERMEDIATE, AND OUTER LAYERS OF SPIRALLY ARRANGED ADHESIVELY UNITED RIBBONS, EACH LAYER INCLUDING AT LEAST ONE RIBBON SPIRALLY WOUND RELATIVE TO THE TUBULAR ELEMENT AXIS, SAID INNER AND OUTER LAYERS BEING CONSTRUCTED OF ETHYLENE TEREPHTHALATE, SAID INTERMEDIATE LAYER BEING CONSTRUCTED OF A METAL FOIL, AND A MALE-THREADED PART POSITIONABLY RECEIVED WITHIN SAID ELEMENT FOR VARYING SAID INDUCTANCE.

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