JPH0634212U - Choke coil device - Google Patents

Abstract

(57) [Summary] [Purpose] To suppress the self-resonance phenomenon of the choke coil and stabilize the high-frequency characteristics. A choke coil 1 is arranged on a printed circuit board 3 via a spacer 2, and leads 1a and 1b at both ends of the choke coil 1 are soldered to the back surface of the printed circuit board 3 by 4a,
Fix with 4b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a choke coil device, and more particularly to an improvement for suppressing a self-resonance phenomenon of a high frequency choke coil.

[0002]

[Prior art]

 As shown in FIG. 7, conventionally, the high frequency choke coil 1 has been directly arranged on the printed circuit board 3 and soldered 4 so-called direct wiring. Thus, the choke coil causes a self-resonance phenomenon when it is used, but since the self-resonance phenomenon of this choke coil always adversely affects the high-frequency characteristics, conventionally it has nothing to do with the choke coil by changing the number of turns of the choke coil. I adjusted it so that the trap of the self-resonance would be included in various frequency bands. Generally, in the case of a choke coil using the same core, the usable frequency band is low when the number of turns of the choke coil is large, and high when the number of turns is small.

For example, in the case of specifications only for VHF (76 to 222 MHz) and UHF (470 to 770 MHz), which have been the television broadcasting band until now, the trap of self-resonance was dealt with as follows by the above method. . (B) Increase the number of turns of the choke coil so that the frequency falls outside the band of 222 to 470 MHz. (B) The number of turns of the choke coil should be reduced so that the choke coil is placed outside the UHF band (470 to 770 MHz).

[0004]

[Problems to be solved by the device]

 However, recently, BS (1035 to 1335 MHz), CS (1360 to 1770 MHz), and CATV (10 to 450 MHz) have been remarkably widespread and developed, and along with this, it has become necessary to broaden the frequency specifications of products. As a result, flat and stable high-frequency characteristics are required over a wide band from low to high frequencies, and the self-resonant frequency of the choke coil must be designed within the specified band. I can no longer deal with it.

Therefore, for example, in order to reduce traps of the self-resonance of the choke coil, a method of floating the choke coil at a certain distance from the printed circuit board may be adopted. However, in the case of aerial wiring, when the printed circuit board after assembly of the components is assembled into the case, the choke coil may fall diagonally and come into contact with the case, causing shorting, which is extremely dangerous in terms of safety.

The object of the present invention is to suppress the self-resonance phenomenon of the choke coil by keeping the distance between the choke coil and the printed circuit board constant, to stabilize the high frequency characteristics, and to ensure the safety and reliability of the choke coil as a product. To improve productivity and mass productivity.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the choke coil device of the present invention arranges the choke coil on a printed circuit board through an insulating spacer, and allows the lead wires at both ends of the choke coil to pass through the holes of the insulating spacer. The main point is that it has been installed in the specified place.

[0008]

[Action]

 By using an insulating spacer, the gap between the choke coil and the printed circuit board is always kept constant, and the self-resonance phenomenon during use is suppressed.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of a choke coil device according to the present invention, 1 is a high frequency choke coil, 2 is an insulating spacer, for example, a plastic spacer, 3 is a printed substrate, and the insulating spacer 2 is a choke coil 1. And the printed circuit board 3, and this space is kept constant. The leads 1a, 1b on both ends of the choke coil 1 are soldered 4a, 4b to the copper foil pattern on the back surface of the printed circuit board 3 through the insertion holes 2a, 2b of the spacer 2 and the insertion holes 3a, 3b of the printed circuit board 3. Fix it.

FIGS. 3 and 4 show an example of the spacer 2, which has a plurality of insertion holes 2a to 2d. It can also be used for multiple types of choke coils with different inter-card pitches and other electrical components. For example, as the spacer in FIG. 4, three types of pitches of l, m ₁ or m ₂ , n can be shared, and since there is no directionality of the top and bottom surfaces of the spacer, m is m _{1 in} addition to l, n. , M ₂ can be used.

Further, the spacer 2 made of plastic has the following characteristics. (A) Since the dielectric constant is as low as about 2 to 4, it has almost no effect on the high frequency characteristics. (B) The insulation is excellent in volume resistivity of about 10 ¹⁴ to 10 ¹⁷ Ω · cm. (C) The heat-resistant temperature is continuously around 120 ° C, and even if it is directly exposed to a high temperature such as a dip, it deforms, and the combustion rate is self-extinguishing.

FIG. 5 is a circuit example of a single branching device using a choke coil. CH1 is a choke coil, C1 to C3 are high frequency bypass capacitors, T1 is a branch transformer, and R1 is an absorption resistance for impedance matching.

In the branch circuit shown in FIG. 5, current flows in the order of OUT → CH1 → IN. On the other hand, the high-frequency signal is divided into an IN-OUT trunk line and an IN-BR branch, and IN → C1 → T1 → C2 → OUT in the trunk direction and IN → C1 → T1 → C3 → BR in the branch direction. Flowing.

A brancher having a constant coupling loss and a small insertion loss is desirable, but in the brancher, it is inevitable that an insertion loss occurs due to the power attenuated by branching from the law of energy conservation.

Considering the n-branch coupling loss C (dB), assuming that the true value of the engagement coefficient is x, x <1, and

Since C = −10 log ₁₀ x (1), the coupling coefficient x is given by the following equation regardless of the number of branches n.

X = 10 ^−0.1C (2) Therefore, from the equation (2), the insertion loss I (dB) is given by the following equation.

## EQU00003 ## I = -10 log (1-nx) =-10 log (1- ^n10-0.1C ) (3)

However, the insertion loss calculated as described above is only a theoretical value, and in an actual product, the insertion loss always becomes a large value due to heat loss and attenuation of high frequency signals by the choke coil.

For example, in the circuit example of FIG. 5, a high-frequency characteristic when a choke coil for passing a current is directly mounted on the board surface and fixed by soldering as in FIG. Shown in a). In the same figure (a), the self-resonance of the choke coil adversely affects the UHF band over 400 to 750 MHz centering on 530 to 540 MHz (the UHF band is 470 to 770 MHz). Therefore, when the spacer 2 is used and the distance between the choke coil 1 and the printed circuit board 3 is set to 2 mm, the characteristic shown in FIG. 5B is obtained, which is improved by 0.5 dB as compared with FIG. This makes it possible to obtain stable characteristics that are close to flat over the entire band.

[0018]

[Effect of device]

 As described above, according to the present invention, it is possible to prevent an adverse effect such as a trap due to a self-resonance phenomenon when a choke coil is used, and to keep the distance between the choke coil and the printed circuit board surface constant with a small error. .

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the above embodiment.

3A is a plan view showing a spacer, and FIG. 3B is a sectional view.

FIG. 4 is a cross-sectional view showing an example of spacer pitch.

FIG. 5 is a branch circuit diagram using a choke coil.

FIG. 6 is a characteristic diagram of the branch circuit.

FIG. 7 is a diagram showing an arrangement example of a conventional choke coil.

[Explanation of symbols]

 1 Choke coil 2 Spacer 3 Printed circuit board 4a, 4b Soldering

Claims (1)

[Scope of utility model registration request] 1. A choke coil is arranged on a printed circuit board via an insulating spacer, and lead wires at both ends of the choke coil are attached to predetermined positions on the printed circuit board through holes of the insulating spacer. Choke coil device.