JPH08154010A - Ferrite bar antenna - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an inexpensive ferrite bar antenna that has a simple shape, does not cause displacement of the antenna coil even when subjected to severe vibration or shock, and has high reliability and productivity. To do. [Structure] Engaging holes 13 are provided in the vicinity of four corners of a rectangular plate-shaped printed circuit board 3, and a spring-like claw portion 12 having an engaging projection 12a is formed at a tip of an edge of an opening upper surface of a metal case 4,
The engagement protrusion 12a of the metal case 4 is fitted into the engagement hole 13 of the printed board 3 for soldering, and the engaging groove 15 is provided on the bottom surface of the ferrite core 1 so that the engaging groove 15 can be engaged. Since the ferrite core 1 is inserted into the metal case 4 after the spring-shaped locking portion 14 is formed, the metal case 4 is reliably joined to the ferrite core 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite bar antenna used for receivers such as pagers.

[0002]

2. Description of the Related Art In recent years, miniaturization of radio receivers, pagers and the like has progressed, and miniaturization of component parts and cost reduction have been demanded. Conventionally, a ferrite bar antenna has been formed by winding a ferrite round bar to form a tuning circuit together with an external variable capacitor.In recent years, however, a metal foil or the like has been wrapped around a ferrite core to form a coil. Ferrite bar antennas in which a resonance circuit is configured by mounting electronic components such as a chip capacitor are widely used.

A ferrite bar antenna for a receiver such as a pager is, for example, shown in FIG.
As shown in the drawing of the publication, groove portions 8 and 10 are formed in two planes of a ferrite core 1 parallel to the longitudinal direction of the rectangular parallelepiped, and a printed circuit board 3 on which a chip type capacitor 2 is mounted is formed in the groove portion. 8 is attached and bonded, and the metal case 4 is fitted into the groove portions 8 and 10 of the ferrite core 1,
The printed circuit board 3 is connected and fixed by the solder 6. A printed circuit board 3 having a structure in which a resonance circuit including a metal case 4, a capacitor 2 and a terminal 5 is formed is generally known as shown in FIG.

As another conventional example, as shown in FIG.
A thin C-shaped metal case 4 that covers the plane and side surfaces of a one-turn coil-shaped ferrite core is formed, and a claw portion 9 and a terminal 5 are provided on the upper edge 16 of the opening of the metal case 4, and the chip-type capacitor 2 and the like are provided. The cutout portions 11 are provided at the four corners of the printed circuit board 3 to which the tuning circuit component of 1 is soldered, the cutout portions 11 of the printed circuit board 3 are fitted into the claw portions 9 of the metal case, and the claw portions 9 are bent and soldered. A ferrite bar antenna in which the ferrite core 1 is inserted in the metal case 4 is known.

As another conventional example, as shown in Japanese Utility Model Publication No. 5-4325 shown in FIG. 7, a conductive material is provided on at least both edges of one surface of the ferrite core 1 in parallel with the longitudinal direction of the rectangular parallelepiped. The pattern 7 is formed, and the tuning circuit component 2a
The substrate 21 on which is mounted is fixed with an adhesive material, and a copper foil 22 serving as an antenna coil having the adhesive material attached to the back surface is attached so as to cover three surfaces parallel to the longitudinal direction, and both ends of the copper foil 22 are attached. A ferrite bar antenna is known in which the joint portions 23 are soldered to both ends of the board 21.

[0006]

In the ferrite bar antenna as shown in FIGS. 5 and 7 described above, a groove for fitting the printed board to the ferrite core is provided for positioning the printed board, There is a problem in that productivity is inferior because it takes time to manufacture such as bonding a printed circuit board or a copper foil to a ferrite core.

Further, when the ferrite bar antenna as shown in FIG. 6 is used in an electronic device which is frequently subjected to severe vibration or shock, the position of the antenna coil may be displaced,
It sometimes slipped off and the tuning circuit could not be formed.

The present invention is intended to solve the above problems, and an object thereof is to have a simple shape and to prevent the antenna coil from being displaced even if it is subjected to severe vibration or shock, and is reliable. It is to provide an inexpensive ferrite bar antenna with high productivity and excellent productivity.

[0009]

According to the present invention, a thin metal case for covering the plane and side surfaces of a ferrite core is formed into a substantially C shape, and a spring-like hook-shaped claw portion is formed at the edge of the opening upper surface of the metal case. And an engaging protrusion is provided at the tip of the claw portion, while an engaging hole facing the engaging protrusion is provided at four corners of the printed circuit board on which the tuning circuit component is soldered, and the engaging hole is provided with the engaging protrusion. Fit the mating protrusions and solder, and further provide the locking groove on the bottom of the ferrite core, the spring-shaped locking on the bottom of the metal case, insert the ferrite core in the metal case, and at the same time as soldering, A ferrite bar antenna is characterized in that a locking groove portion and the locking portion are locked.

[0010]

According to the present invention, engaging holes are provided in the vicinity of the four corners of a rectangular plate-shaped printed circuit board, spring-like claw portions are provided at both ends of the upper edge of the opening of the metal case, and the tips of the claw portions are engaged. Since the protrusion is formed and the engaging protrusion of the claw portion of the metal case is fitted into the engaging hole of the printed board and soldered, the printed board can be positioned extremely easily. Also,
Since the printed circuit board is fixed and then soldered, the printed circuit board can be easily soldered without rattling. Further, a locking groove is provided on the bottom surface of the ferrite core, and a spring-shaped locking portion is formed on the surface of the metal case facing the substrate, so that the locking groove and the locking groove can be locked. Lock the locking part. As described above, since the ferrite core is locked to the metal case, the metal case is securely joined so as not to rattle the ferrite core. For this,
The position of the metal case does not shift or come off.

[0011]

Embodiments of the present invention will be described with reference to the drawings. 1 is an external perspective view of a ferrite bar antenna of the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is an external perspective view of a printed circuit board, and FIG. 4 is an external perspective view of a metal case.

As shown in FIG. 1, the ferrite bar antenna of the present invention covers a rectangular parallelepiped ferrite core 1 with chamfered ridges in the longitudinal direction, and a plane and side surfaces parallel to the longitudinal direction of the ferrite core. It is composed of a C-shaped one-turn coil metal case 4 and a printed circuit board 3.

As shown in FIG. 2, the metal case 4 is provided with an engagement projection 12a on the back of a spring-shaped claw portion 12 which is fitted into the engagement holes 13 near the four corners of the printed circuit board 3. , The bottom surface of the ferrite core 1 has a locking groove 15
On the other hand, the metal case 4 is provided with the engaging portion 14 at a position facing the engaging groove 15, and the engaging hole 13, the engaging protrusion 12a, the engaging groove 15 and the engaging portion 14 are fitted. I am combining.

As shown in FIG. 3, the printed board 3 has conductive patterns 7 formed on a plane and engaging holes 13 are provided at four corners to which the chip type capacitors 2 are electrically connected.

The metal case 4 is a substantially C-shaped plate-shaped one-turn coil that encloses the plane and side surfaces of the ferrite core.

Next, the manufacturing process will be described. FIG.
As shown in FIG. 4, the engaging holes 1 are formed by cutting in the vicinity (4 places) of four corners of the rectangular plate-shaped printed circuit board 3 on which the tuning circuit components such as the chip type capacitor 2 and the conductive pattern 7 are provided.
3 is provided. As shown in FIGS. 1 and 4, an opening upper surface edge portion 16 (4 locations) of a metal case 4 formed in a substantially C-shaped plate of a one-turn coil that constitutes an antenna coil that covers the plane and side surfaces of a rectangular parallelepiped ferrite core 1 ), A notch of a predetermined length is made to stand up, and the stand-up portion is bent and bent into a hook shape to form a spring-shaped claw portion 12.
In addition, as shown in FIG.
2a is provided.

As shown in FIG. 4, U-shaped cuts are made in the bottom surface (two locations) of the metal case 4, and the metal case 4 is raised and bent to form the spring-shaped engaging portion 14. Further, as shown in FIG. 2, concave locking grooves 15 are formed on the bottom surface (two locations) of the ferrite core 1.

Next, the printed circuit board 3 is fitted into the claw portion 12, and the engaging projections 12a provided on the claw portion 12 are engaged with the engaging holes 13 of the printed circuit board 3, so that the claw portion 12 and the conductive pattern 7 are formed. By soldering the printed circuit board, the printed circuit board can be easily positioned and fixed to the metal case and electrically connected.

Further, the ferrite core 1 is attached to the metal case 4
Is inserted from the opening side surface of the
The metal case 4 can be easily fixed and attached to the ferrite core 1 by fitting the metal case 5 into the ferrite core 1.

According to the present embodiment, the printed circuit board 3 and the metal case 4 can be securely connected with little rattling.

[0021]

According to the present invention, an engaging hole is provided in the long side edge portion of a printed circuit board, and a spring-like claw portion having an engaging projection is formed at the tip of the upper surface edge portion of the opening of the metal case. Is inserted in the metal case, the engaging projection is fitted in the engaging hole, and the claw portion and the conductive pattern of the printed circuit board are soldered, so that the printed circuit board can be easily positioned, and the printed circuit board is placed in the metal case. Since it is fixed and then soldered, it can be easily soldered.

Further, since the ferrite core is inserted into the metal case and the locking groove provided on the bottom surface of the ferrite core is fitted into the spring-shaped locking portion provided on the bottom surface of the metal case, the metal case is fixed to the ferrite core. Can be easily fixed,
The metal case can be prevented from slipping off or coming off even in an environment subject to severe vibration or shock.

Further, since the metal case forming the antenna coil is in close contact with the ferrite core, it is possible to prevent the metal case from being displaced or twisted, and to suppress variations in characteristics.

Since the work of attaching the printed circuit board to the metal case and attaching the metal case to the ferrite core is simple and has a simple structure, a workable, highly reliable and inexpensive ferrite bar antenna can be provided. Can be provided.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of a ferrite bar antenna according to the present invention.

FIG. 2 is a sectional view of the ferrite bar antenna shown in FIG.

3 is an external perspective view of the printed circuit board shown in FIG.

4 is an external perspective view of the metal case shown in FIG.

FIG. 5 is an external perspective view showing a first example of a conventional ferrite bar antenna.

FIG. 6 is an external perspective view showing a second example of a conventional ferrite bar antenna.

FIG. 7 is an external perspective view showing a third example of a conventional ferrite bar antenna.

FIG. 8 is a circuit diagram of a ferrite bar antenna.

[Explanation of symbols]

 1 Ferrite Core 2 (Chip Type) Capacitor 2a Circuit Parts 3 Printed Circuit Board 4 Metal Case 5 Terminal 6 Solder 7 Conductive Pattern 8, 10 Groove 9 Claw 11 Notch 12 (Spring-like) Claw 12a Engagement 13 Engagement hole 14 Engagement part 15 Engagement groove 16 Opening top edge 21 Substrate 22 Copper foil 23 Joining part

Claims (1)

[Claims] 1. A thin metal case that covers the plane and side surfaces of a ferrite core is formed in a substantially C shape, and a hook-shaped spring-like claw portion is formed at the edge of the opening upper surface of the metal case. An engaging protrusion is provided at the tip, while an engaging hole facing the engaging protrusion is provided at four corners of the printed circuit board to which the tuning circuit component is soldered, and the engaging protrusion is fitted into the engaging hole and soldered, Furthermore, a locking groove is provided on the bottom of the ferrite core,
A ferrite bar characterized in that a spring-shaped locking portion is provided on the bottom surface of a metal case, a ferrite core is inserted into the metal case, and the locking groove and the locking portion are locked simultaneously with soldering. antenna.