JPS645877Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency noise removal filter that removes high frequency components of noise entering electronic equipment and prevents malfunctions of the electronic equipment.

FIG. 1A shows a first conventional example of a high frequency noise removal filter, where 1 is a connector, 2 is a connector pin installed in the connector 1, and 3 and 4 are printed patterns. Reference numeral 5 denotes a discrete high-frequency noise removal filter, one end of which is connected to the connector pin 2 through the printed pattern 3, and the other end connected to the circuit section 6 through the printed pattern 4. 7 is a printed circuit board on which all of these are mounted. Further, as shown in FIG. 1B, the filter 5 includes a coil 8, a capacitor 9,
It is composed of a connector side terminal 10 and a circuit side terminal 11.

FIG. 2A shows a second conventional example of a high frequency noise removal filter used for integrated circuits, etc., where 12
is an integrated circuit (hereinafter referred to as IC), 13 is IC12
The lead 14 is a discrete bypass capacitor, one end of the capacitor 14 is connected to the lead 13 through a printed pattern 15, and the other end is connected to a ground pattern 16. Second
Figure B is the equivalent circuit of Figure 2A, where 17 is the IC
12 is a power supply terminal, and 18 is an input terminal of the IC 12. Further, 19 is an equivalent inductance, which equivalently represents the inductance between the IC 12 and the capacitor 14 in FIG. 2A.

However, in the first conventional example, the filter 5
is mounted between the connector 1 and the circuit section 6, which increases the mounting area and increases the number of mounting steps. Furthermore, in the second conventional example, a land (not shown) is required when installing the capacitor 14, making it difficult to install the capacitor 14 close to the IC 12. Therefore, the printed pattern 15 connecting the capacitor 14 and the IC 12 becomes longer, and the inductance of the coil 19 shown in the equivalent circuit increases, so that the capacitor 14 has drawbacks such as being unable to sufficiently remove high frequency noise. In other words, the golden rule of high frequency bypass, which is to provide a capacitor as close as possible to the element, cannot be observed.

It is an object of the present invention to provide a high frequency noise removal filter that eliminates the above-mentioned drawbacks, has a smaller mounting area, reduces the number of mounting steps, and can sufficiently remove high frequency noise.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3A shows a cross section of the high frequency noise removal filter of the present invention, and FIG. 3B shows a side view of the filter.
Here, 20 is a conductor as a lead, which forms one electrode of a capacitor, and is a pair of electrodes provided facing each other. 21 is a conductor forming the other electrode of the capacitor, and this electrode 21
are commonly opposed to each electrode 20, a dielectric 22 is inserted between both electrodes 20 and 21, and these are embedded in an insulator 23 to form a capacitor. Note that the side of the conductor 21 that does not face the electrode 20 is exposed to the outside of the insulator 23.

FIG. 3C shows a first implementation example of the filter of the present invention, where 24 is the filter of the present invention, 25 is a dual-in-line type IC, and 26 is a pair of input/output leads of the IC 25, which one on the output side. Connect one of them to a ground line (not shown). Each lead 20 of the filter 24 sandwiches a pair of input/output leads 26 of the IC 25 from both sides, fixing the filter 24 and maintaining contact with the leads 26. .
FIG. 3D shows an equivalent circuit of the filter of the present invention, where 27 is a capacitor, which is constituted by the electrodes 20, 21 and dielectric 22 shown in FIG. 3A.
In this figure, 20 corresponds to one electrode, lead, and terminal of the capacitor 27, and 21 corresponds to the other electrode of the capacitor 27, and corresponds to a common line connecting each electrode. In addition, the capacity of each capacitor is
Usually, it is suitable to set it to several 100 pF to several 1000 pF.

Next, the operation of the filter of the present invention will be explained. Third
The impedance of the capacitor 27 shown in Figure D is:
Impedance is inversely proportional to frequency when the capacitance is constant, so the lower the frequency, the higher the impedance. That is, in the low frequency region, the coupling impedance between the terminals 20 is extremely high, so that the state is approximately equal to the open state. Therefore, the low frequency region of the current led to the lead 26 shown in FIG. 3 flows into the IC 25, and the IC 25 performs the desired operation. On the other hand, in the high frequency region of noise, the coupling impedance between each terminal 20 is extremely low, resulting in a state almost equivalent to a short circuit state. Therefore, the high frequency region of the current flowing into the lead 26 is transmitted to the ground line (not shown) connected to the lead 26 shown in FIG. 3C via the terminal 20, capacitor 27 and common line 21 shown in FIG. ) flows into. As mentioned above, the low frequency region of the current supplied to the lead 26 is
Since the high frequency region is guided to the IC 25 and bypassed to the ground line (not shown) avoiding the IC 25, the high frequency noise is removed and the IC 23 operates normally.

FIG. 4 shows another implementation example of the filter of the present invention,
The same parts as in Fig. 3 are given the same reference numerals. Here, 28 is a small screw made of a conductor, 29 is a case made of a conductor, and the small screw 28 is screwed into the case 29 and is in contact with the conductor 21. The operation of the filter 24 is exactly the same as in the previous implementation example, but in this implementation example, the high frequency current is passed through the lead 20, filter 24, common conductor 21, machine screw 28, and case 29 to the ground line (not shown). Pour.

As explained above, according to the present invention, the filter is mounted on the IC and the filter leads are sandwiched between the IC leads, which reduces the mounting area and the number of mounting steps compared to the conventional method. , high frequency noise can be sufficiently removed. In addition, the filter of the present invention can be easily installed and removed due to its structure, so when testing the noise resistance of a prototype circuit, for example, depending on the characteristics of the high-frequency noise to be removed,
The capacitance of the capacitor can be easily considered.

[Brief explanation of the drawing]

FIG. 1A is a perspective view showing a first conventional example in which a high-frequency noise removal filter is mounted, FIG. 1B is its equivalent circuit diagram, FIG. 2A is a perspective view showing a second conventional example in which the filter is mounted, FIG. 2B is a circuit diagram equivalently showing the internal structure, FIG. 3A is a cross-sectional view of the filter of the present invention, FIG. 3B is a side view thereof, and FIG. 3C is a cross-sectional view of the filter of the present invention.
FIG. 3D is an equivalent circuit diagram of the filter, and FIG. 4 is a front view showing a second implementation example of the filter. 1... connector, 2... connector pin, 3,
4, 15: Printed pattern, 5: High frequency noise removal filter, 6: Circuit section, 7: Printed circuit board, 8: Coil, 9: Capacitor, 10
......Connector side terminal, 11 ......Circuit side terminal, 12
...Integrated circuit (IC), 13...lead, 14...
Bypass capacitor, 16... Earth pattern,
17: Power supply terminal, 18: Input terminal, 19:
Equivalent inductance, 20... First electrode, 21...
...second electrode, 22...dielectric, 23...insulator,
24: Filter of the present invention, 25: IC, 26:
...input/output lead, 27...capacitor, 28...
Machine screw, 29...conductor.

Claims (1)

[Scope of utility model registration request] In a high-frequency noise removal filter used in a dual-in-line electronic device, a plurality of pairs of first electrodes are arranged to face each other, and a second electrode faces each other with a dielectric interposed between the first electrodes. 1. A high-frequency noise removal filter, characterized in that the filter is configured to be mounted on the electronic circuit by sandwiching a plurality of pairs of input/output leads of the electronic circuit between the plurality of pairs of first electrodes.