GB1599431A

GB1599431A - Tuning apparatus and method of manufacturing the same

Info

Publication number: GB1599431A
Application number: GB14772/78A
Authority: GB
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 1977-04-15
Filing date: 1978-04-14
Publication date: 1981-10-07
Also published as: DE2816042A1; DE2816042C2

Description

(54) TUNING APPARATUS AND METHOD OF MANUFACTURING THE SAME (71) We, MURATA MANUFACTURING Co. LTD., a Japanese corporation, of 26-10, Tenjin 2-chome, Nagaokakyo-shi, Kyoto-fu, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a tuning apparatus and a method of manufacturing the same.

Fig. 1 is a sectional view of a construction for explanation of a prior art tuning apparatus of interest to the present invention, illustrating a conventional intermediate frequency transformer. The intermediate frequency transformer 10 shown therein comprises a resin base 12 having a recess 11 formed in the bottom thereof, with coils 13 mounted on the base 12. In association with said coils 13, there are provided a drum core 14 and a cap core 15, which is threadedly installed, adjustments of the inductance being made by tuning said cap core 15. Received in the recess 11 formed in the base 12 is a tuning capacitor 16 of e.g. the lead-attached cylinder type. A plurality of round-pin terminals 17 are pressure-inserted into the surface of the base 12. Leads 18 from said coils 13 and leads 19 from said capacitor 16 are wound around said pin terminals 17 and fixed in position by the solder dip process.

The conventional intermediate frequency transformer as described above, however, has disadvantages or problems as described in the following.

When the pressure-inserting operation on the terminals 17 is to be carried out by an automatic machine, the cost will increase unless the number of articles to be produced is relatively large. Since the tuning capacitor 16 employed is, in most cases, of the lead-attached cylinder type, it is difficult to automate the installing operation, and the size of the apparatus is large. Since the tuning capacitor 16 is received in the recess 11 formed in the bottom surface of the base 12, the performance characteristics might be deteriorated by the sticking of flux during the soldering operation. Since the tuning capacitor 16 itself is exposed, it is susceptible to moisture and other influences from the ambient atmosphere. Further, since the terminals 17 are pressure-inserted after the formation of the base 12, they tend to come off, breaking the leads.

In accordance with the present invention there is provided a method of manufacturing a tuning apparatus comprising a hollow base member within which a capacitor is received, a coil fixed to the base member, and terminals for providing electrical connections to said coil and capacitor, the method including the steps of providing a combshaped electrically conductive member, electrically connecting the capacitor between the ends of two teeth of the comb-shaped member, inserting the ends of the teeth and the capacitor into said hollow base member, filling the hollow base member with resin to retain the ends of the teeth therein, and severing the teeth from the comb-shaped member to separate the teeth and thereby provide two said terminals.

The invention also provides a tuning apparatus comprising a capacitor chip, a coil, a base member in which is received said capacitor chip and on which said coil is mounted, and a plurality of external terminals projecting from said base member and electrically connected to said capacitor chip and coil, said plurality of external terminals comprising at least two which have been formed from a comb-shaped part comprising an electrically conductive metal member having a plurality of comb teeth, at least two of said plurality of comb teeth having had their front ends inserted into a hollow space in said base member and having been fixed in position by resin poured into said hollow space, the roots of said comb teeth having been severed to separate said comb teeth from each other, thereby providing said at least two external terminals, said capacitor chip having two terminals directly connected to the portions of said at least to external terminals corresponding to said front ends of said comb teeth, whereby said capacitor chip and the front ends of said comb teeth are covered with said resin within said hollow space.

In a preferred embodiment of the invention, said comb-shaped member has an additional comb tooth, which serves to temporarily position said capacitor chip by clamping the latter between it and the said two comb teeth, in which condition said capacitor chip is electrically connected to the two comb teeth, said additional comb tooth preferably also being severed when said comb teeth are severed.

The advanages which can be achieved using the invention include the provision of tuning apparatus which is suited for mass-production, in which the capacitor is protected from ambient influences, and whose characteristics do not vary from those of other tuning apparatus produced in the same batch. Also highly reliable electrical connections between the elements of the apparatus and the external terminals can be achieved.

Arrangements embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a construction for explanation of a prior art tuning apparatus of interest to the present invention Fig. 2 is a sectional view of an intermediate frequency transformer according to an embodiment of the invention; Fig. 3 is a perspective view, exploded and enlarged, illustrating the principal portion of the intermediate frequency transformer of Fig. 2; Fig. 4 is an enlarged section taken along the line 4-4 of Fig. 3; Fig. 5 is a sectional view of an intermediate frequency transformer according to another embodiment of the invention; and Fig. 6 is a perspective view, exploded and enlarged, illustrating the principal portion of the intermediate frequency transformer of Fig. 5.

Fig. 2 is a sectional view of an intermediate frequency transformer according to an embodiment of the invention. Fig. 3 is a perspective view, enlarged and exploded, illustrating the principal portion of the intermediate frequency transformer of Fig.

2.

Referring to Fig. 2, the arrangement related to the coils 23 of an intermediate frequency transformer 20 shown therein will be described. In association with the coils 23, there are provided a core 24 and a cap core 25. The cap core 25 is supported on a support block 40 to be later described so as to be rotatable with respect to a resin base 22, and the inductance is adjusted according to the rotation thereof.

More specifically, the downward inner surface of the cap core 25 and the upward surface of the upper end of the core 24 are each formed with a step, so that as the cap core 25 is rotated, the opposed area between said steps and the distance therebetween vary. Next, the arrangement related to the resin base 22 will be described.

The bottom surface of the resin base 22 is best seen in Fig. 3. The arrangement of the resin base 22 will now be described with reference to Fig. 3. The bottom surface is formed with a substantially H-shaped recess 21. As will be later described, a capacitor and external terminals will be inserted into said recess 21 and fixed in position by pouring resin thereinto.

Mutually oppositely directed outer lateral surfaces of the base 22 are provided with grooves 30 for receiving the leads 28 (Fig.

2) from the coil 23 therein to guide them to the terminals.

Also referring to Fig. 3, the arrangement related to the terminals will be described.

One formed part 31 is obtained by pressworking an electrically conductive metal sheet, and it is in the form of a comb.

Only a portion including two comb teeth 32 is shown in Fig. 3, but actually the formed part 31 has many comb teeth 32, and the process of insertion into the base 22 to be later described is performed by using the formed part 31 having many comb teeth 32. The ends of these two combi teeth 32 are formed with connecting pieces 33 inwardly extending toward each other, said connecting pieces 33 having been worked to have a suitable form. Between this pair of connecting pieces 33, a capacitor chip 26 having terminals on opposite sides thereof is disposed, being positioned by a suitable jig (not shown) and soldered as at 34. Such formed part 31 is inserted into the recess 21 in a direction shown in a dot-and-dash line. The other formed part 35 is also comb-shaped, and though not so illustrated, it is formed with a number of comb teeth 36. The ends of the comb teeth 36, preferably, are formed with bends 37.

This formed part 35, too, is guided in a direction shown in a dot-and-dash line and inserted into the recess 21. After insertion, resin is poured into the recess 21. Therefore, when the resin has set, the parts are fixed in position. Alternatively, the pouring of resin and the insertion of the formed parts 31 and 35 may be effected in reverse order. As is clear from the shape of the front ends of the comb teeth 32 and 36, the comb teeth, unlike the previously described pin terminals 17, will never come off. The formed parts 31 and 35 are then severed at places indicated by dot-and-dash lines A and B. When they are thus severed the comb teeth 32 and 36 are respectively separated to form flat terminals 27 (Fig.

2). The leads 28 from the coils 23 are led through the grooves 30 to the terminals 27 and wound around the latter and are fixed in position by the solder dip process.

Further, a case 38 is prepared, whereby the assembly including the base 22 and the rotatable cap core 25 is housed. In addition, the upper end surface (Fig. 2) of the case 38 is provided with an opening 38a for permitting engagement with the upper end surface of the cap core 25 to rotate the latter. The cap core 25 is downwardly urged by spring tabs 38b projecting from the inner surface of the upper end wall of the case 38, whereby a suitable rotative resistance is imparted to the cap core 25.

Preferably, the capacitor chip 26 is of the multilayered type. The multilayered type capacitor is superior in that it has a large capacity for its small size. Fig. 4 is a section taken along the line 4-4 of Fig. 3.

Referring to Fig. 4, the multilayered type capacitor chip 26 comprises a plurality of ceramic dielectric layers 26a alternating with inner electrodes 26b, and outlet electrodes 26c disposed on opposite sides.

Alternate inner electrodes 26b are connected to one outlet electrode 26c and the other inner electrodes 26b are connected to the other outlet electrode 26c. The masses of solder 34 for electrically connecting the capacitor chip 26 to the comb teeth 32 are disposed in contact with both the outlet terminals 26c and the connecting pieces 33.

The coils 23 and core 24 to be fixed on the base 22 through a support block 40 may be fixed on the base in advance, or they may be fixed thereon after the resin has fixed the ends of the teeth in position and the base structure including the base 22 has been completed.

Figs. 5 and 6 illustrate another embodiment of the invention. In Figs. 5 and 6, the parts which correspond to those shown in Figs. 2 and 3 are given like reference characters, and only the features peculiar to this embodiment will be described below.

In the arrangement related to the terminals, one formed part 31 includes a set of three comb teeth 32a, 32b, 32c. Only a portion including a set of three comb teeth 32a, 32b 32c is illustrated, but actually the formed part 31 has a plurality of sets each comprising three such comb teeth 32a, 32b 32c. Of these three comb teeth 32a, 32b, 32c in each set, the comb teeth 32a and 32b on the opposite sides are formed with connecting pieces 33a and 33b inwardly extending toward each other, said connecting pieces having been worked to have a suitable form.

Further, of the comb teeth 32a, 32b, 32c, the intermediate one 32c has been worked so that it is capable of mechanically holding the capacitor chip 26 by utilizing the resilience of the formed part 31, as shewn in Fig. 6. Therefore, of the three comb teeth 32a, 32b, 32c, the two comb teeth 32a and 32b on the opposite sides have the capacitor chip 26 placed thereon and serve as connector comb teeth to which the capacitor chip is directly connected by the asses of solder 34a and 34b. The intermediate comb tooth 32c serves as a presser comb tooth which presses the capacitor chip 26 toward the connector comb teeth.

In reality, in order to connect tbe capacitor chip 26 to the connecting pieces 33a and 33b, the formed part 31 with the capacitor chip 26 mechanically htld by the comb teeth 32a and 32b is immersed in a bath of solder (not shown) and then withdrawn therefrom whereby the connecting pieces 33a and 33b and the electrodes are joined by the masses of solder 34a and 34b. This process can be performed more easily than in the preceding embodiment. Such formed part 31 is inserted into tbe recess 21 in the direction indicated by the dot-and-dash line.

The other formed part 35 is also in the form of a comb, and, though not so illustrated, it is fored with many comb teeth 36, as in the case of the formed part 31.

The comb teeth 36 are formed with notches 37a adjacent their ends, and their ends are sharpened. The formed part 35 is also guided in the direction indicated by the dot-and-dash line and is inserted into the recess 21.

After the formed parts are inserted into the recess, a resin is poured into the recess 21 and allowed to set, whereby the formed parts 31 and 35 are fixed in position. As is clear from the shape of the front ends of the comb teeth 32a, 32b, 32c and 36, the comb teeth, unlike the previously described pin terminals 1, will never come off. The formed parts 31 and 35 are then severed at places indicated by the dot-and-dash lines C and D, whereupon the comb teeth 32a, 32b, 32c and 36 are separated from each other to form independent flat terminals 27 (Fig. 5). The leads 28 from the coils 23 are guided to the terminals 27 via the grooves 30 and wound around the terminals 27 and are fixed in position by the solder dip process. The terminal 27 corresponding to the comb tooth 32c is not connected to the capacitor chip 26 as it is electrically isolated from the latter, and it is possible to use said terminal as an intermediate tap terminal by winding a lead 28 from the coil 23 therearound. Further, the presence of the terminal 27 on the bottom surface of the base 22 makes the positions of the terminals asymmetrical, facilitating the ascertainment of directionality, i.e. of the primary and secondary sides. Further, a case 38 is prepared, whereby the portion including the base 22 and cap core 25 are housed.

In addition, in this embodiment, as best seen in Fig. 6, the comb teeth 32a, 32b, 32c and 36 are bent into a V-shape in crosssection so as to have a longitudinally extending ridge. With such arrangement, even if the formed parts 31 and 35 are formed of a thin material, their resistance to bending can be increased.

While the embodiments described so far have been directed to an intermediate frequency transformer, they may be high frequency transformers, the same concept being generally applicable to any tuning apparatus including an inductance and a capacitance.

WHAT WE CLAIM IS:- 1. A tuning apparatus comprising a capacitor chip, a coil, a base member in which is received said capacitor chip and on which said coil is mounted, and a plurality of external terminals projecting from said base member and electrically connected to said capacitor chip and coil, said plurality of external terminals comprising at least two which have been formed from a comb-shaped part comprising an electrically conductive metal member having a plurality of comb teeth, at least two of said plurality of comb teeth having had their front ends inserted into a hollow space in said base member and having been fixed in position by resin poured into sad hollow space, the roots of said comb teeth having been severed to separate said comb teeth from each other, thereby providing said at least two external terminals, said capacitor chip having two terminals directly connected to the portions of said at least two external terminals corresponding to said front ends of said comb teeth, whereby said capacitor chip and the front ends of said comb teeth are covered with said resin within said hollow space.

2. A tuning apparatus as claimed in claim 1, wherein in addition to said two comb teeth, a third comb tooth of said combshaped part has been inserted into said hollow space, said third comb tooth abutting against a surface of said capacitor chip, the resilience of said third comb tooth acting to press said capacitor chip against said two comb teeth.

3. A tuning apparatus as claimed in claim 1 or 2, wherein said front ends of said comb teeth are so shaped as to prevent the comb teeth from being removed from said resin.

4. A tuning appartus as claimed in any preceding claim, wherein the front ends of the two comb teeth to which the two terminals of said capacitor chip are connected are formed to extend toward each other.

5. A tuning apparatus as claimed in any preceding claim, wherein said capacitor chip has its terminals at opposite ends and is electrically connected to said two external terminals in such a manner as to bridge the latter.

6. A tuning apparatus as claimed in any preceding claim, wherein a core member is provided for said coil.

7. A tuning apparatus as claimed in claim 6, wherein said core member is adjustably installed.

8. A tuning apparatus as claimed in any preceding claim, wherein there is provided a casing member for receiving said base member and said coil.

9. A tuning apparatus as claimed in claim 7, wherein said core member is rotatable and there is also provided a casing member for rotatably supporting said core member and for receiving said base member and said core member.

10. A tuning apparatus as claimed in any preceding claim, wherein said comb teeth are bent into a V-shape in cross-section so as to have a longitudinally extending ridge.

11. A method of manufacturing a tuning apparatus comprising a hollow base member within which a capacitor is received, a coil fixed to the base member, and ter minais for providing electrical connections to said coil and capacitor, the Method including the steps of providing a combshaped electrically conductive member, electrically connecting the capacitor between the ends of two teeth of the comb-shaped member, inserting the ends of the teeth and the capacitor into said hollow base member, filling the hollow base member with resin to retain the ends of the teeth therein, and severing the teeth from the comb-shaped member to separate the teeth and thereby provide two said terminals.

12. A method as claimed in claim 11, wherein said comb-shaped member has an additional comb tooth, the method including the step of temporarily positioning said capacitor between said additional comb tooth and the said two comb teeth so that it is held by the resilience of the teeth before electrically connecting said temporarily positioned capacitor to the said ends of the two teeth, said step of severing the teeth from the comb-shaped member including the step of severing said additional tooth.

13. A method as claimed in claim 11 or 12, wherein the step of inserting the ends of the teeth and the capacitor into said hollow base member precedes the step of filling said hollow base member with resin.

14. A method as claimed in claim 11 or 12, wherein said step of inserting the ends of the teeth and the capacitor into said hollow base member follows the step of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. housed. In addition, in this embodiment, as best seen in Fig. 6, the comb teeth 32a, 32b, 32c and 36 are bent into a V-shape in crosssection so as to have a longitudinally extending ridge. With such arrangement, even if the formed parts 31 and 35 are formed of a thin material, their resistance to bending can be increased. While the embodiments described so far have been directed to an intermediate frequency transformer, they may be high frequency transformers, the same concept being generally applicable to any tuning apparatus including an inductance and a capacitance. WHAT WE CLAIM IS:-

1. A tuning apparatus comprising a capacitor chip, a coil, a base member in which is received said capacitor chip and on which said coil is mounted, and a plurality of external terminals projecting from said base member and electrically connected to said capacitor chip and coil, said plurality of external terminals comprising at least two which have been formed from a comb-shaped part comprising an electrically conductive metal member having a plurality of comb teeth, at least two of said plurality of comb teeth having had their front ends inserted into a hollow space in said base member and having been fixed in position by resin poured into sad hollow space, the roots of said comb teeth having been severed to separate said comb teeth from each other, thereby providing said at least two external terminals, said capacitor chip having two terminals directly connected to the portions of said at least two external terminals corresponding to said front ends of said comb teeth, whereby said capacitor chip and the front ends of said comb teeth are covered with said resin within said hollow space.

filling said hollow base member with resin.

15. A method as claimed in any one of claims 11 to 14, including the step of fixing the coil to said base member before inserting the ends of the teeth and the capacitor into said hollow base member.

16. A method as claimed in any of claims 11 to 14, including the step of fixing the coil to said base member after the ends of the teeth have been retained in position in the base member by the resin.

17. A method as claimed in any one of claims 11 to 16, wherein said capacitor is a capacitor chip having terminals formed at its opposite ends.

18. A method as claimed in claim 17, wherein said step of electrically connecting the capacitor between said ends of the two comb teeth comprises the step of performing a solder dip operation while said capacitor is temporarily positioned so that its terminals are in contact with said ends of said comb teeth.

19. A method of manufacturing a tuning apparatus, substantially as herein described with reference to Figures 2 to 4 or Figures 5 and 6 of the accompanying drawings.

20. A tuning apparatus made by a method as claimed in any one of claims 11 to 19.

21. A tuning apparatus substantially as herein described with reference to Figures 2 to 4 or Figures 5 and 6 of the accompanying drawings.