JPH0559812U - Ferrite bead - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to simplify the work of attaching ferrite beads, which is used to prevent unwanted radiation from electronic components. [Structure] A cylindrical ferrite bead 1 has a through hole 2 for passing a lead wire. The openings of the through holes 2 are covered with a resin 3 having elasticity. When the lead wire is inserted into the through hole 2 through the resin 3, a strong fixing structure can be obtained by the elastic force of the resin 3. Resin 3 that covers the opening
Instead of this, a resin plug arranged so as to project from the inner wall of the cylindrical portion of the ferrite bead 1 may be used. Alternatively, a fixing member having elasticity may be attached along the through hole 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ferrite bead directly attached to a lead wire of an electronic component in order to suppress high frequency noise and the like, and more particularly to a fixing structure of the ferrite bead.

[0002]

[Prior Art]

 FIG. 14 shows a typical shape of conventional ferrite beads. The ferrite bead 101 has a cylindrical shape provided with a through hole 102 into which a lead wire of an electronic component is inserted. The ferrite beads 101 are a kind of inductance element obtained by sintering ferrite powder, for example. It is attached to the lead wires of various electronic parts and has the function of suppressing high-frequency loss and suppressing noise. It is effective when used in low impedance circuits such as power supplies. It is also effective in preventing overshoot and undershoot of digital signals such as clocks and harmonics. Furthermore, it is also used to prevent abnormal oscillation of the high frequency amplifier circuit.

[0003]

[Problems to be solved by the device]

 The problem to be solved by the invention will be briefly described with reference to FIG. In the illustrated example, a ferrite bead 101 is attached to a lead wire 104 of a power transistor 103 used for a switching power supply. If the ferrite beads are not used, unnecessary radiation from the lead wire 104 may occur and interfere with the normal operation of other devices. Therefore, it is used as a noise countermeasure. In this case, the lead wire 104 was inserted into the through hole of the ferrite bead 101 as shown on the left side of the figure, and then the adhesive 105 was applied and fixed as shown on the right side of the figure. If the ferrite beads 101 are not fixed, the audible sound may be emitted due to the vibration due to the current flowing through the lead wire 104 or the mechanical vibration from the outside, or in the worst case, the lead wire may be damaged and cause the disconnection. However, there is a problem that the work of applying the adhesive for fixing the ferrite beads often requires manual labor and the workability is poor. Further, it is difficult to make the amount of adhesive applied evenly, and there is a problem in that excess and deficiency cause various defects. As described above, the conventional ferrite beads have a structure in which they are fixed after being attached to the lead wire, and thus are inconvenient to handle.

FIG. 16 is a schematic view showing another example of use. In this conventional example, a ferrite bead 101 is attached to a lead wire of an element or component incorporated on a printed circuit board 106 on which a high frequency circuit of a tuner is mounted. In this case as well, it is used as a measure against unwanted radiation in the high frequency circuit. In this example, the ferrite bead 101 is passed through the lead wire 104. However, if it is left as it is, it may loosen due to vibration. So after fixing it, I applied a screw lock. As described above, there is a problem that post-treatment is required, workability is poor, and the process is bulky.

FIG. 17 shows another example of use. In this conventional example, a ferrite bead 101 is attached to the output pin 104 of the high-speed digital IC 107, which is also used as a measure against unnecessary radiation. In this case as well, there is a problem that the work becomes complicated because it is necessary to take some fixing means after inserting the output pin 104 into the through hole of the ferrite bead 101.

[0006]

[Means for Solving the Problems]

 In view of the above-mentioned problems or problems of the conventional technology, the present invention aims to provide a ferrite bead having an improved structure capable of being fixed to a lead wire at the same time as being mounted. In order to achieve such an object, in a cylindrical ferrite bead having a through hole for passing a lead wire, a means of coating the opening of the above through hole with a resin having elasticity beforehand was taken. Alternatively, a means of previously providing a resin for fixing the lead wire so as to protrude from the inner wall of the cylindrical portion toward the through hole was taken. According to another aspect, a measure is taken in which an elastic member for fixing the lead wire is previously attached along the through hole of the ferrite bead.

[0007]

According to the present invention, the elastic resin or elastic fixing member for fixing the lead wire is incorporated in advance in the ferrite bead having the through hole, and is actually used. Therefore, when the lead wire is passed through the through hole of the ferrite bead, the ferrite bead is automatically fixed to the lead wire by the operation of the fixing resin and the fixing member. Therefore, there is no need for post-processing and post-processing for fixing separately as in the conventional case.

[0008]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of a ferrite bead according to the present invention. The left part shows a perspective view, and the right part shows a sectional structure. In this example, the lead wire fixing resin 3 is coated so as to cover the openings of the through holes 2 formed in the cylindrical ferrite beads 1. It is preferable that the material of the resin 3 is excellent in elasticity and has good adhesiveness to the surface of the ferrite 1. For example, a silicone adhesive is used as the resin 3. In the illustrated example, the resin 3 is provided so as to cover only one opening of the through hole 2, but the present invention is not limited to this. In some cases, the resin 3 may be introduced not only into the openings but also into the through holes 2. Alternatively, the openings at both ends of the through hole 2 may be covered. In any case, the resin 3 must have a certain elasticity and be soft enough to allow the lead wire to pass through. The resin 3 made of a silicone adhesive or the like can be quantitatively supplied to each ferrite bead using a dispenser or the like.

Next, a method of using the ferrite beads shown in FIG. 1 will be described with reference to FIG. The left side of FIG. 2 is a perspective view showing a state in which the ferrite beads 1 are attached to the lead wires 4 of the electronic component, and the right side shows the sectional structure thereof. The lead wire 4 is inserted into the ferrite bead 1 through the resin 3 that covers the opening of the through hole 2. Since the resin 3 has flexibility, it can be easily broken, and the broken end portion 5 is press-fitted between the inner peripheral surface of the through hole portion 2 and the outer peripheral surface of the lead wire 4 to prevent elastic stress. Thus, the ferrite beads 1 are firmly fixed to the lead wires 4. Therefore, the ferrite beads 1 are fixed at the same time when the lead wire 4 is inserted, and no post-treatment is required.

FIG. 3 is a schematic perspective view showing a second embodiment of the ferrite bead according to the present invention. The same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals to facilitate understanding. The difference from the first embodiment is that a flexible fixing member or fixture 6 is used instead of the flexible resin coating. As shown in the figure, the fixture 6 is attached inside the central through hole 2 formed in the ferrite bead 1 in advance. Both ends of the fixture 6 are exposed from both end openings 7 and 8 of the through hole portion 2 and engage with the outer peripheral surface of the ferrite bead 1.

FIG. 4 is a schematic perspective view showing the shapes of the components forming the ferrite beads shown in FIG. The left side shows the fixture 6, and the right side shows the sintered tubular part 9 of ferrite. The fixture 6 has a substantially U-shaped cross section, and can be manufactured in large quantities at low cost by injection molding of plastic or the like. Hooks 10 and 11 are provided at both ends of the fixture 6 so as to engage with the upper end 12 and the lower end 13 of the tubular part 9, respectively. The intermediate portion 14 of the fixture 6 is curved in a dogleg shape and has a predetermined elastic force. When this fixing tool 6 is inserted into the through hole 2 from one opening of the tubular part 9, the intermediate part 14 is inserted into the tubular part 9 while penetrating through the through hole 2 while slightly deforming. At this time, as shown in FIG. 3, the intermediate portion 14 of the fixture 6 projects radially inward of the through hole 2.

Next, a method of using the ferrite beads described above will be described with reference to FIG. When one end of the lead wire 4 is inserted through one opening 7 of the ferrite bead 1, the lead wire 4 is inserted while pressing the intermediate portion 14 of the fixture 6 toward the inner wall of the through hole portion 2. After entering the designated position, stop the insertion and complete the mounting and fixing work. The ferrite beads 1 and the lead wires 4 are firmly fixed to each other by the radial repulsive force of the deformed intermediate portion 14.

In order to manufacture the ferrite beads shown in FIG. 3, the two parts shown in FIG. 4 may be manually combined, but in order to manufacture them in large quantities and at low cost, an automatic assembly method should be adopted. Is preferred. An example of automatic assembly will be described below with reference to FIGS. 6 to 8. First, FIG. 6 shows a fixture 6 having a shape suitable for automatic assembly. A tongue piece 16 is integrally provided in advance at one end of the main body of the fixture 6 by injection molding or the like through a connection 15.

As shown in FIG. 7, the individual fixtures 6 are taped on the carrier for automatic supply at predetermined intervals via the tongue pieces 16. The individual fixing tools 6 thus taped are sequentially supplied to the automatic assembly machine.

Finally, as shown in FIG. 8, the supplied fixture 6 is incorporated into a tubular part 9 made of ferrite. The automatic assembly machine used in this process consists of a normal insertion device. After the assembly, the connection wire 15 is cut from the vicinity of the root and the unnecessary tongue piece 16 is cut off.

Next, a third embodiment of the ferrite bead according to the present invention will be described with reference to FIG. The left side of this figure shows a perspective appearance, and the right side shows a cross-sectional shape. As before, the same parts or portions are given the same reference numerals to facilitate understanding. The difference from the second embodiment is that a resin component having a specific shape, for example, a resin plug 17 is used in place of the elastic fixture. The resin stopper 17 is processed by injection molding a resilient synthetic resin material such as silicone rubber or urethane rubber. The resin plug 17 is press-fitted into a through hole 18 provided in the side wall of the ferrite bead 1, and the tip of the plug 17 projects from the inner wall of the through hole 2. Since the resin plug 17 is pressed into the through hole 18 while being elastically deformed, it cannot be easily removed.

FIG. 10 is a perspective view showing the shape of a tubular part 19 that constitutes a ferrite bead. The tubular part 19 is obtained by sintering ferrite powder. The through hole 2 is formed along the central portion, and the through hole 18 communicating with the through hole 2 is provided.

FIG. 11 is a sectional view for explaining a method of using the ferrite beads shown in FIG. The ferrite bead 1 is attached by inserting the tip of the lead wire 4 from one opening 7 of the ferrite bead 1. At this time, the tip 20 of the resin plug 17 protruding into the through hole 2 is crushed by the lead wire 4 and elastically deformed. Due to the stress generated by this deformation, the lead wire 4 and the ferrite bead 1 are firmly fixed to each other. As shown in the figure, the deformation of the front end portion 20 extends beyond the opening diameter of the through hole 18, so that the detachment of the resin plug 17 is effectively prevented.

The ferrite beads according to the third embodiment described above can also be manufactured by an automatic assembly method. This example will be described with reference to FIGS. 12 and 13. First, as shown in FIG. 12, each resin plug 17 is preliminarily processed by injection molding as an integral structure connected to the tongue piece 16 via the connection wire 15. Similar to the example shown in FIG. 7, the resin stopper 17 is supplied to the automatic assembling machine by using taping and sequentially inserted into the through hole 18 of the tubular part 19. When the insertion is completed, the connection 15 is cut from the root to obtain the ferrite beads.

FIG. 13 shows a modification. In this example, the wire connection 15 and the resin plug 17 are separate, and the tip of the wire connection 15 is inserted into the resin plug 17. When the resin plug 17 is completely assembled, the wire connection 15 is pulled out together with the tongue piece 16. In this way, the tongue piece 16 and the connection 15 can be reused repeatedly.

[0021]

[Effect of the device]

 As described above, according to the present invention, in a cylindrical ferrite bead having a through hole for passing a lead wire, a resin member for fixing the lead wire covers the above through hole or a cylinder. It is provided so as to project from the inner wall of the shaped portion. Alternatively, a fixture for fixing the lead wire is attached along the through hole. Therefore, it is possible to insert the lead wire into the ferrite bead and fix it at the same time, and there is an effect that a post-process such as adhesion is not required as in the conventional case and rationalization can be achieved. Further, there is an effect that it is possible to prevent defects and the like that have been caused by the variation in the coating amount of the adhesive as in the past.

[Brief description of drawings]

FIG. 1 is a schematic view showing a first embodiment of a ferrite bead according to the present invention.

FIG. 2 is a schematic diagram for explaining a method of using the ferrite beads according to the first embodiment.

FIG. 3 is a perspective view showing a second embodiment of a ferrite bead according to the present invention.

FIG. 4 is a perspective view showing components used for manufacturing a ferrite bead according to a second embodiment.

FIG. 5 is a perspective view for explaining a method of using the ferrite beads according to the second embodiment.

FIG. 6 is a perspective view showing a fixture having a shape suitable for automatic assembly.

FIG. 7 is a schematic diagram for explaining taping of the fixture shown in FIG.

FIG. 8 is a perspective view showing an assembled state of the fixture shown in FIG.

FIG. 9 is a schematic view showing a third embodiment of a ferrite bead according to the present invention.

FIG. 10 is a perspective view showing a tubular ferrite component used in the third embodiment.

FIG. 11 is a sectional view for explaining a method of using the third embodiment.

FIG. 12 is a perspective view showing a state in which the ferrite beads according to the third embodiment are automatically assembled.

13 is a cross-sectional view showing a modified example of FIG.

FIG. 14 is a perspective view showing a conventional typical ferrite bead.

FIG. 15 is a schematic diagram showing a state in which conventional ferrite beads are attached to a power transistor.

FIG. 16 is a schematic view showing a state in which a conventional ferrite bead is attached to an electronic component of a high frequency circuit.

FIG. 17 is a schematic view showing a state in which a conventional ferrite bead is attached to an output pin of a digital IC.

Claims (2)

[Scope of utility model registration request] 1. A cylindrical ferrite bead having a through hole for passing a lead wire, wherein a resin for fixing a lead wire is formed so as to cover the through hole or to protrude from an inner wall of the cylindrical part. Ferrite beads characterized by being arranged. 2. A cylindrical ferrite bead having a through hole for passing a lead wire, wherein a fixing member for fixing the lead wire is attached along the through hole. ..