US3528047A

US3528047A - Miniaturized high-frequency transformer

Info

Publication number: US3528047A
Application number: US823271A
Authority: US
Inventors: Kazutomo Iwata
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1968-05-21
Filing date: 1969-05-09
Publication date: 1970-09-08
Anticipated expiration: 1987-09-08
Also published as: DE1925404B2; FR2008964B1; JPS4712731Y1; FR2008964A1; GB1260243A; DE1925404A1

Description

' P 1970 :KAZUTOMdlWATA 3,528,047

MINIATURIZED HIGH-FREQUENCY TRANSFORMER Filed May 9, 1969 I INVENTOR KHZ LLTDHO IWH TR ATTORNEY 5 United. States Patent US. (3]. 33683 3 Claims ABSTRACT OF THE DISCLOSURE A miniaturized high-frequency transformer comprising: a cap core having an adjusting magnetic core at its center and an adjustment groove at its closed end; a core supporter having a hole at its center and another adjustment groove at its closed end; a terminal board member having coils wound thereon and a through tapping hole, the core supporter being in threaded engagement with the tapping hole so that the core supporter is firmly and adjustably coupled with the terminal board member and the resulting assembly is covered with the cap core with the adjusting magnetic core inserted into the hole in the core supporter; and a shield case for substantially enclosing the assembled transformer structure, whereby the inductance of the transformer is adjustable on either one of the opposite sides of the structure.

The present invention relates to a miniaturized highfrequency transformer used for example, in a miniaturized television receiver and is intended to provide a miniaturized transformer structure which has high performance and the inductance of which can be adjusted on either one of the opposite sides of the structure so that the transformer structure can be assembled on a printedcircuit board.

Generally, in case the operating frequency of a highfrequency transformer is not so high, a cap-shaped ferrite core which covers coils is used in order to prevent quality factor (Q) of the transformer from being lowered due to the proximity effect by a shield case, and in almost all the conventional high-frequency transformers, the arrangement has been such that coils are wound on a ferrite core which is drum-shaped and the resulting core assembly is adjustably covered with a cap-shaped core which is provided with an adjusting groove at its closed end and is further threaded on its outer periphery for the purpose of moving the cap-shaped core to adjust the inductance of the transformer.

In such an arrangement as mentioned above, the adjustment of the inductance of a high-frequency transformer is performed only on one side (e.g., at the top portion) of the transformer, so that a completed miniaturized device such as a miniaturized television receiver must have included a space necessary for performing adjustment of the inductance of such a transformer, thus obstructing miniaturization of completed devices which include such a transformer.

The present invention relates to a high-frequency trans- ,former free from the disadvantages mentioned above.

The present invention will be explained referring to the accompanying drawings illustrating an embodiment of the present invention, in which:

FIG. 1 is a half cross-sectional front view of a high frequency transformer in accordance with an embodiment of the present invention;

FIG. 2 is a perspective view of the major parts of the transformer shown in FIG. 1 is a disassembled state; and

FIG. 3 is a perspective view of a cap-shaped core which is used in the transformer.

In the drawings, numeral 1 designates a terminal board member in the center of which a hole 2 is bored to define a tapping cylindrical wall and which, at its upper portion, has a winding section 4. Coils 3 are wound on the section 4. The hole 2, hereafter referred to as tapping hole, of the terminal board member 1 is.bored in the form of a through hole, and a shaft section 6 of a core supporter 5 made of a thermoplastic resin in a threaded engagement with the tapping hole 2 by means of self-tapping technique. Namely, a plurality of ridges 7 are provided on the periphery of the shaft section 6 in the axial direction of the shaft section 6 so that the ridges 7 may be tapped when the core supporter 5 is adjustably fitted into the tapping hole 2 by simultaneously turning and depressing the core supporter 5. And at the bottom of the shaft section 6 of the core supporter 5 an adjustment groove 8 is formed, on a flange section 9 of the core supporter 5 two protuberances 10 are formed, and a hole 11 is defined extending through the flange section 9 and part of the shaft section 6. The core supporter 5 having such a construction as mentioned is coupled with a cap core 13 which is in the form of a hollow cylinder and has an adjusting magnetic core 12 extending axially of the cap core 13 and located at the center of the cylinder. Funnel-shaped holes 20 tapering downwardly as viewed in FIG. 3 are defined in the top plate of the cap core 13 at positions to be engaged with the protuberances 10 of the core supporter 5 so that the protuberances 10 may be fixed into the holes 20 and fused and united with each other by means of thermal welding. The adjusting magnetic core 12 of the cap core 13 is inserted into the hole 11 of the core supporter 5. At the top of the cap core 13 another adjustment groove 14 is formed.

And a shield case 15 wholly covers the resulting assembly including the members as shown in FIG. 2. At the bottom of the shield case 15 earth terminals 16 is formed and at the top of the shield case 15 an adjustment groove 19 corresponding to the groove 14 in the cap core 13 is formed. Further, one end of each of terminal pins 17 is buried in the terminal board member 1 and recesses 18 for lead line are provided for in the terminal board member 1.

In the miniaturized high-frequency transformer made according to the present invention as mentioned above, when the operating frequency has to be adjusted by mov ing the cap core 13 upward or downward, the adjustment can be accomplished, when necessary, not only at the top of the transformer using the adjustment groove 14 of the cap core 13 but also at the bottom of the transformer using the adjustment groove 8 of the core supporter 5 through the tapping hole 2 in the terminal board member 1, and even if the miniaturized transformer is assembled on a printed-circuit board, for example in a miniature television receiver, definition of a through hole in the printed-circuit board will suflice for a satisfactory adjustment of the inductance of the transformer due to the fact that on either one of the two opposite sides of the transformer, i.e., through the

adjustment groove

14 or 8 or both, inductance adjustment is possible. Thus, miniaturization of a completed device can be attained.

Further, the core supporter 5 is madeof a thermoplastic resin, the protuberances 10 are formed on the top 9 of the core suporter 5 and both are coupled by means of thermal welding after the protuberances 10 have been fixed in the holes 20, so that the assembly can be accomplished easily and fixedly.

Further, since a plurality of ridges 7 are provided on the periphery of the shaft section 6 of the cores supporter 5 in the axial direction so that the ridges 7 are tapped by the tapping hole 2 in the terminal board memberIby self-tapping technique, the threaded engagement between the core supporter 5 and the terminal board member 1 is stable, and smooth upward and downward movement of the cap core 13 can be accomplished. Thus, the present invention can make a great contribution to the field of miniaturization of electronic devices.

What is claimed is:

1. A miniaturized high-frequency transformer comprising: a terminal board member having a through tapping hole at its center extending in its axial direction and coils wound on one end of said terminal board member; a core supporter having an adjustment groove at its closed end and a hole at its center extending in its axial direction and adapted to be in threaded engagement with said tapping hole of said terminal board member; a cap core having an adjustment groove at its closed end and an adjusting magnetic core at its center extending in its axial direction, said adjusting magnetic core being inserted into said hole in said core supporter; and a shield case covering the resulting assembly.

2. A high-frequency transformer as claimed in claim 1., in which said core supporter is made of a thermoplastic resin, at least two protuberances are formed at an open end of said core supporter so that said protuberances are fixed into holes prepared at said closed end of said cap core the number of which corresponds to the number of protuberances, and said core supporter and said cap core are coupled with each other by means of thermal welding.

3. A high-frequency transformer as claimed in claim 1, in which said core supporter is made of a thermoplastic resin, a plurality of ridges are formed on a shaft section of said core supporter for forming threads thereon in the axial direction so that the shaft section of the core supporter is in threaded engagement with said tapping hole in said terminal board member by simultaneously turning and depressing said core supporter so as to adjustably fit the latter into said tapping hole to effect a self-tapping operation.

References Cited UNITED STATES PATENTS 2,318,415 5/1943 Patzschke et al. 336-136 2,435,630 2/1948 Ketcham 33687 XR 2,717,984 9/1955 Hale et al. 33683 XR 2,823,359 2/1958 Wentworth 336131 XR 3,227,980 1/1966 Roser 336-83 XR 3,309,640 3/1967 Oshima 33683 XR THOMAS J. KOZMA, Primary Examiner US Cl. X.R. 33687, 136