JPS6297415A - High frequency filter for electronic equipment - Google Patents

Abstract

PURPOSE:To eliminate a fault due to high frequency induced current caused by an incident radio wave by connecting directly a grounding electrode width a metallic casing. CONSTITUTION:A high frequency filter 70 is provided in a casing 10 of an electronic equipment D and the said filter 70 has a common electrode 71. Lead chips 71a, 71b of the common electrode 71 are connected to a bottom wall 12 of the casing 10 through land holes 37a, 37b of a printed board 30. Then they are connected also to copper foil films 31a, 31b of the printed board 30 via the land holes 37a, 37b. Since the common electrode 71 of the high frequency filter 70 is connected directly to the casing 10 in this way by the lead chips 71a, 71b, the connection impedance is small, the attenuation of high frequency noise is excellent and the high frequency filter cut-off characteristic is improved.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a high frequency filter for electronic equipment, particularly for radio wave generation in broadcasting stations, amateur radio stations, citizen radio stations, personal radio systems, military radar, etc. Electricity caused by various radio waves emitted from the source 78! Related to high frequency filters for protecting electronic equipment from disturbances.

[Prior art]

Conventionally, in this type of high frequency filter, for example, as disclosed in Japanese Patent Application Laid-Open No. 58-61583,
A chip-type capacitor is used, which reduces the transmission of high-frequency noise components based on various radio waves to the input/output lines of electronic devices.
There are some that are designed to prevent this from happening.

[Problem that the invention seeks to solve]

However, in such a high frequency filter,
Because the ground electrode is connected to the metal gauging of the high-frequency filter via the ground wire formed on the back side of the printed circuit board, the impedance between the ground electrode and the metal casing increases unnecessarily, and this type of high-frequency filter Therefore, in order to deal with such a problem, the present invention provides a high frequency filter for electronic equipment in which the grounding electrode is directly connected to the conductive gauging of the high frequency filter. This is what we are trying to do.

[Means for solving problems]

In solving this problem, the structural features of the present invention are as follows:
A high frequency filter interposed between a connection line extending from an external circuit in a conductive device (II) and an electronic element provided on the surface of a printed circuit board assembled in the conductive casing. In this case, the grounding electrode of the high frequency filter is directly connected to the inner wall portion of the conductive gauging.

[Effect]

By configuring the present invention in this manner, radio waves from a radio wave generation source such as a broadcasting station, an amateur radio station, a personal radio system, or a military radar are incident on the connection line, and a high-frequency induced current is generated in the connection line. Even if the high-frequency filter generates , the impedance between the two becomes very small in a wide radio frequency band due to the direct connection of the grounding electrode to the inner wall of the conductive casing. Since the filtering characteristics of the high-frequency filter are enhanced over a wide radio frequency band, the high-frequency induced current flowing into the high-frequency filter is reliably filtered by the conductive casing due to the above-mentioned high-filtering function of the high-frequency filter. As a result, the electronic device can always operate properly by receiving only the signal current from the external circuit flowing through the connection line and the high-frequency filter, without being disturbed by the high-frequency induced current, that is, the radio waves. .

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show an electronic control system to which the present invention is applied, which is installed in a vehicle. Various electrical components such as sensors and actuators placed in various parts of the vehicle [J], 1. J2. IJ3. U4.
[J5 and each of these electrical components LJI, tJ2. [J3. U
4. Each input/output signal line Wl, W2 . W3. W4. W
5 and electronic devices (2) connected to each other via the respective terminals. In this case, each of the input/output signal lines W1 to W5 is lengthened based on the relative arrangement relationship between the input and output signal lines W1 to W5 (see FIG. 2).

As shown in FIG. 1, the electronic device has a casing 10 made of a metal good conductor.Elongated holes 11a formed in the front wall 11 of the casing 10 are provided with input/output signal lines W.
A connector 20 connected to the connector 20a connected to W1 to W5 is fitted. The connector 20 has inverted I-shaped connector pins PI, P2, P3 . P4. P5, and each of these connector pins P1. P2. P3. P4. P5 connects each input/output signal line Wl, W2 via the connector 20a at each inner end.
．． W3. W4. Each is connected to W5. however,
The casing lO is placed in a non-grounded state (i.e.,
It is assembled in an insulated state).

The printed circuit board 30 is supported above the bottom wall 12 within the casing 10 by a plurality of support members (not shown) made of metal good conductors. , 31b are fixed to the casing 10 at intervals in the left-right direction of the casing 10, as shown in FIGS. 1 and 3. In such a case, each copper foil film 31a.

31b is the support member that supports the bottom wall 12 of the casing 10.
electrically connected to. On the other hand, each wiring pattern 32a is provided on the upper surface of the printed circuit board 30.

33 a, 34 a, 35 a, 36 a
are the connector pins PI, P2 . P3. P
4. These wiring patterns 32a are arranged in the front-rear direction of the casing 10 in correspondence with P5, respectively.

33a, 34a, 35a, 36a have connector pins PI, P2. P3. P4. The lower ends of P5 are connected to each other. Further, on the upper surface of the printed circuit board 30, each wiring pattern 32b, 33b is provided.

34b, 35b, and 36b are each wiring pattern 32a.

The wiring patterns 32b, 33b, 34b, 35b, 36b are arranged in the front-rear direction of the casing 10 corresponding to the wiring patterns 33a, 34a, 35a, and 36a, respectively.
and each wiring pattern 32a, 33a, 34a,
A predetermined interval is provided between each opposing end between 35a and 36a.

Furthermore, pudding I-,! & On the upper surface of the plate 30, each electronic element 40, 50, 60 and a high frequency filter 70 constituting the main part of the present invention are mounted with a sheath 1, and the electronic element 7-4
0 is fixed to the upper surface of the printed circuit board 30 with its lead terminal 41, and each of the wiring patterns 32b and 33b is attached with a half liter at 42°43.
It has been J. The electronic device 50 has its respective lead terminals 51 .
At 52, each wiring pattern 34b.

35b, each half a day is marked on the electronic element 6.
0 is soldered onto the wiring pattern 36b at its first end 'F-61, and is fixed to the upper surface of the printed circuit board 30 at its lead terminal 62.

As shown in FIG.
0 on the upper surface of the printed circuit board 30. This high frequency filter 70 has a common electrode plate 71, and this common electrode plate 71 has a low impedance that extends in the shape of 1 from both left and right ends, respectively, as shown in FIGS. 1 and 3. Each lead piece 71a, 71b made of a conductive material is connected to the printed circuit board 30 and the copper foil film 31.
A common land hole 37a1 and a land hole 37b common to the printed circuit board 30 and copper foil film 31b are respectively passed through and suspended on the bottom wall 12 of the casing 10, and each wiring pattern 32a to 36a and each wiring pattern 32b to 36b, and is supported in parallel to one or two sides of the upper surface of the printed circuit board 30 between opposite ends thereof. In such a case, each lead piece 71a.

71b is each copper foil film 31a at each intermediate portion thereof.

31b and soldered onto the bottom wall 12 at each lower end (see FIG. 3).

As shown in FIG. 1, the high-frequency filter 70 includes an insulating layer 72 formed on the upper surface of a common electrode plate 71, and strip-shaped strips disposed on the upper surface of this insulating layer 72 in parallel with each other in the front-rear direction of the casing 10. Each electrode piece 73, 74, 75, 76.
77, and the insulating layer 72 is made of a dielectric material (for example, lead iron niobate and lead iron tungstate dielectric) having a dielectric constant ε that changes as shown in FIG. 5 in relation to the radio frequency f. dielectric material whose main component is a dielectric material. This means that the filtering characteristics of the high frequency filter 70 are flat over a wide radio frequency band. In such a case, the dielectric constant ε of the insulating layer 72 is still sufficiently high compared to the dielectric constant of air, even if it decreases as the radio frequency f increases.

Further, the thickness, the length in the left-right direction, and the length in the front-back direction of the insulating layer 72 are 0.5 m, 20 m, and 10 m, respectively.

As shown in FIGS. 1 and 4, the electrode piece 73 is fixed to the upper surface of the insulating TM 72 between the rewiring patterns 32a and 32b, and extends in a shape from both the front and rear ends of the electrode piece 73. Each lead piece (made of conductive material)
73a and 73b are the land holes 38a common to the wiring pattern 32a and the printed circuit board 30, and the wiring pattern 3.
2b and the printed circuit board 30, and are inserted into the respective wiring patterns 32a and 32b.
It is attached. .

In addition, each of the remaining electrode pieces 74, 75, 76.11
As shown in the figure, substantially similar to the case of the electrode piece 73,
Each pair of wiring patterns 33a, 33bH34a, 34b
; 35a, 35b; 36a.

These electrode pieces 74, 75°76.77 are fixed to each upper surface portion of the insulating layer 72 between
Each pair of lead pieces (>74a made of a conductive material) extends in a beveled shape from both front and rear ends of the .

74bH75a, 75b; 76a, 76b; 77a, 7
7b is a pair of land holes 38b, 39b.

38c, 39cH38d, 39d; 38e, 39e are inserted into each pair of wiring patterns 33a, 33b; 34a
, 34b; 35a, 35b; 36a.

36b, respectively. In addition, each of the land holes 38 b, 38 c, 38 d,
38e indicates each wiring pattern 33a under the printed circuit board 30, substantially similar to the land hole 38a.

34a, 35a, and 36a, respectively, while the above-mentioned land holes 39b, 39c,
Substantially similar to the land hole 39a, the wiring patterns 33b, 341), 3511. 36
b, respectively.

In the 4 embodiments with 11 and 7 configurations, lJ
As shown in Figure 2, various radio waves 1. When two people shoot, is this radio wave Ir based on high frequency induction? ti current l is each input/output signal line Wl.

W2. W3. W4. Both connectors 2Qa are guided by W5,
20 to 1 lil A-frequency filter 70.

However, the dielectric constant ε of the insulating layer 72 of the I[G frequency filter 70 has the radio frequency characteristics shown in FIG.
! ! 31a, 31b and the bottom wall 12 of the gauging 10, respectively, so in the formation of a low radio frequency f, the high frequency induced current (2) is partially connected to the common electrode plate 71, each -1- Ff4 directly flows into the bottom wall 12 of the casing 10 through the pieces 71a and 71b, and in the remaining part, the 1111 electrode F; 2.71, a part of each lead piece 71a and 71b, and each copper foil film 31a , 31
b, and flows into the bottom wall 12 of the casing 10 via the respective support members.

Moreover, in the high band of radio frequency f, each reed piece 7]a, a part of 71b, each copper foil film 31a.

31b and the common ill\i electrode plate 7 via the above-mentioned support members.
The impedance between 1 and the bottom wall 12 is green juice] 9fXI
Although it increases due to the impedance of W31a, 3]b,
1 ffl electrode plate 7 for each one via a and 71b
The impedance between 1 and the bottom wall 12 is
Since the low impedance of 1 a and 7 l b is suppressed to a low level, almost the entire high-frequency induced current I is transferred to the bottom wall 12 of the ligating 10. Direct inflow.

In this way, each piece 71a, 71b is gauged 1.
This kind of high-frequency filter 4. The disconnection characteristics can be further improved. Therefore, each electrical component II I to U5 and each electronic element 40
. . . . . . . to . Each connector 20a, 20. Each wiring pattern 32a to 36a.

Each lead piece 738-77a, each electrode piece 73-77°, each lead piece 73b-77b, each wiring pattern 32b-36b
This will be ensured through each step.

In addition, in the first embodiment, each lead piece 71a,
71b is soldered to the bottom wall 12 of the casing 10, but instead of this, each lead piece 7]a, 71b may be fastened to the bottom wall 12 at its lower end with a screw. Alternatively, each lead piece 71a, 71b may simply touch the bottom wall 12 at its respective lower end.

Further, in the first embodiment, each lead piece 71a,
71b to the bottom wall 12 of the casing 10 (
However, instead of this, each piece 1' piece 71a, 71b is extended in the direction.
A two-walled lid of the casing 10 at one end (not shown)
It may be tightened with screws, soldered, or brought into contact with fli.

Next, a second embodiment of the present invention will be described with reference to FIG. 6. In this second embodiment, the high frequency filter 80 is replaced with the high frequency filter 70 in the first embodiment, and the upper surface of the printed circuit board 30 is Its structural feature lies in the fact that it is vertically installed.

The high frequency filter 80 has a common electrode plate 81 made of low impedance, and this common electrode plate 81 has a sixth
As shown in the drawings and FIG. 7, a longitudinal land hole 38f common to the printed circuit board 1 30 and each copper foil film 31a, 31b.
(in place of each runt hole 37a, 37b) and extends downward through each copper foil membrane 31a, 31b, and its lower end 81a is connected to a plurality of screws 12 on bottom wall 12 of casing 10.
a to 12a, each wiring pattern 32a to 3
6a and each of the wiring patterns 32b to 36b. In such a case, the common electrode 81 connects each copper foil film 3 at its intermediate portion.
1a and 31b.

The high frequency filter 80 also includes the overlapping border N72 described in the first embodiment, the alumina substrate 82, and the inverted U-shaped electrode pieces 83, 84, 85 . 86°87, and the insulating layer 72 is fixed to the curved surface of the common electrode (k81) above the -L plane of the pudding 1-1L plate 30, while the insulating layer 72 is fixed to the curved surface of the common electrode (k81). Corresponding to shrine 72” (J(i
The common electrode 4 is fixed to the 1r surface of the lfl electrode plate B1.
&81 is reinforced. Each electrode piece 83-87i; l:,
The insulating layer 72 and the printed circuit board 3 are arranged in parallel with each other so as to be perpendicular to the r-th (as shown in the figure, the printed circuit board 30).
0 and 1 are being grouped from one side to the other. As shown in FIG. 6 and FIG.
A lead piece 88a (made of a conductive material) extending in a 14-shape from the lower end of the front arm 83a of the electrode piece 83 is inserted into the runt hole 38a in the first embodiment. It is inserted through the wiring pattern 32a and attached with a half film, and on the other hand, a 17-shaped piece (made of conductive material) extends from the lower part of the rear arm 83b of the electrode piece 83.
89a is inserted through the runt hole 39a in the first embodiment and connected to the wiring pattern 32b (marked with 1. In this case, the rear arm portion 83b of the electrode piece 83 and the front and rear arm portions 83a.

The connecting portion between 83b is the rear surface of the alumina substrate 82, and!
It is located at an appropriate distance from the upper edges of the edge layer 72, common electrode plate 81, and alumina substrate 82.

In addition, each of the remaining electrode pieces 84, 85, 86.87
As shown in the figure, substantially the same as in the case of electrode piece 83,
Each pair of wiring patterns 33a, 33b; 34a, 34bH35 at each front arm portion 84a, 85a, 86a, 87a
a, 35b; 36a.

36b, each front arm portion 84a, 85a, 86a,
87a, extending in a letter shape from the lower end of each 1'
Piece 88b (made of conductive material).

88c, 88d, 88e, each land hole 38b, 38c, 38d, 38 in the first embodiment
e respectively, and each wiring pattern 33a, 34
a, 35 a, 3 G half 1 [1 with IJ
has been done. - direction, each electrode piece 84, 85, 86.87
Lead pieces (4
Consisting of electric material shrines) 89b, 89c, 89d, 89e (
(not shown) represents each land hole 3 in the first embodiment.
9b, 39c, 39d, and 39e, respectively, to form the respective wiring patterns 33b, 34b.

It is soldered to 35b and 36b. In such a case, the front arm portions 84a, 85 of each electrode piece 84, 85, 86, 87
The remaining parts except a, 86a, and 87a are electrode pieces 83
As in the case of , the rear surface of the alumina substrate 82, the insulating layer 72, the common electrode plate 81, and the alumina substrate 82.
It is located at an appropriate distance from the edge. In the high frequency filter 80 configured in this way, the common electrode plate 81 and each of the electrode pieces 83 to 87 correspond to the common electrode plate 7J and each of the electrode pieces 73 to 77 in the first embodiment.

In this embodiment configured as described above, when various radio waves E are incident on the vehicle, a high frequency induced current l based on the radio waves E is applied to each input/output signal line W, as in the first embodiment.
1 to W5, passes through both connectors 20a and 20, and flows into the high frequency filter 80. However, the dielectric constant ε of the insulating layer 72 of this high frequency filter 80 has the same radio frequency characteristics as in the first embodiment, and the common electrode piece 81 is attached to each copper foil F31a, 31b with a half LH as described above. At the same time, screws 12a to 12a are attached to the bottom wall 12 of the gauging 10.
Therefore, in the low band of radio frequency f, a part of the high-frequency induced current I flows directly into the bottom wall 12 through the common electrode plate 81, and the remaining part flows directly into the bottom wall 12. , the upper part of the common electrode plate 81 and the copper foil film 31
a, 31b and flows into the bottom wall of the casing IO via the support member.

In addition, in the high band of radio frequency 1, each copper foil film 3
1a, 31b and the common electrode plate 8 via each of the supporting members.
1 and the bottom wall 12 of each copper foil H'J31. The impedance between the bottom wall 12 and the first half of the JL jm electric Ifi plate 81 via the F half of the common 3m electrode plate 81 increases due to the impedance of the common electrode plate 81. Since it is suppressed to a low level based on the impedance, almost the entire high-frequency induced current (2) directly flows into the bottom wall 12 of the casing 10 through the conductive electrode plate 81.

In this way, the common electrode plate 81 is connected to the bottom wall 12 of the casing 10.
The high-frequency induced current I is connected to the bottom wall 12 of the casing 10 over a wide radio frequency band by tightening the screws 12a to 12a, so that the cutoff characteristics of this type of high-frequency filter are improved. can be further enhanced. Therefore, each electrical component U1 to U5 and each electronic element 4
The transmission and reception of only the inflow and outflow signal current between 0 and 6o is the radio wave E.
Despite the existence of
, each lead piece 88a to 88e1, each electrode piece 83 to 87, each lead piece 898 to 89e, each wiring pattern 32b to 36
11 respectively.

In this case, since the high frequency filter 80 is vertically disposed on the printed circuit board 30 in the same way as the high frequency filter 70 in the first embodiment, the common electrode plate 81 is connected to each electronic element 40.
.about.60 from the connector 20, it is also possible to block various radio waves that directly enter the electronic devices 40 to 60 from the inner opening of the connector 20.

In the second embodiment, the common electrode plate 81 is attached to the bottom wall 12 of the casing 10 with the screw 12 at its lower edge 81a.
a to 12a, but instead of this, the common electrode plate 81 may be soldered to the bottom wall 12 at its lower edge 81a. It may also be implemented by simply contacting the bottom wall 12 at 81a.

Further, in the second embodiment, the common electrode plate 81 was made to hang down to the bottom wall 12 of the casing 10.
Instead, as shown in FIG. 8, the common electrode plate 81 is extended in the left-right direction, and its left and right edges 81b and 81c are soldered to the left and right side walls of the casing 10, respectively, and tightened with screws. Alternatively, it may be implemented by simply making contact.

Further, in the second embodiment, the common electrode plate 81 was arranged to hang down in a plate shape to the bottom wall 12 of the casing 1o, but instead of this, as shown in FIG. Multiple terminals f from the edge? l'+81A to 81A may be hung down like a bottle and soldered to the bottom wall 12, fastened with screws, or brought into contact with a skewer. The portion may extend upward in the shape of a bottle and may be soldered to the lid of the casing 10, fastened with a screw, or simply brought into contact.

Further, in each of the embodiments described above, the casing 10 made of a good metal conductor is maintained in an ungrounded state, but the casing 1o is not limited to this and may be maintained in a grounded state on a part of the vehicle body. If the electronic circuit parts such as the electronic elements 40, 50, 60, etc. have resistance to radio waves, only a part of the casing 1o may be formed of a metal good conductor.

Further, in each of the above embodiments, an example in which the present invention is applied to an electronic control system for a vehicle has been described; The present invention may also be applied and implemented when the electronic control system disposed at a fixed location has relatively long input/output signal lines.

Incidentally, in each of the above embodiments, the high frequency filter 70.
When experimenting with the cutoff characteristics of 80, characteristic curves i, n, and m as shown in FIG. 10 were obtained. However, the characteristic curve I is based on each lead piece 71a of the high frequency filter 70,
71. b or represents the attenuation characteristic of the high frequency noise component when the common electrode plate 81 of the high frequency filter 80 is soldered only to each copper foil film 31a, 31b, and the characteristic curve (2) represents the attenuation characteristic of the high frequency noise component when the common electrode plate 81 of the high frequency filter 80 is soldered only to each lead piece 71a, 71b or the common electrode plate 81. represents the attenuation characteristics of high-frequency noise components when simply brought into direct contact with the inner wall of the casing 10, and the characteristic curve (2) represents the attenuation characteristics of high-frequency noise components when the
gauging] represents the attenuation characteristics of high frequency noise components when it is directly attached to the inner wall of 0 with H1 attached 4J or screwed. According to this, 'l! from characteristic curve 1!
Sequentially high frequency filtering 1t on l'i11 curve Ill or IJ
It is understood that the li characteristic is +I'tl<.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts showing the first embodiment of the present invention, and FIG. Figure 3 is a cross-sectional view taken along the line 3-3 in Figure 1, Figure 4 is a cross-sectional view taken along the line 4-4, and Figure 5 shows the radio frequency f of the dielectric constant ε of the insulating layer in Figure 1. FIG. 6 is a graph showing the relationship between
FIG. 7 is a sectional view taken along line 7-7 in FIG. 6, FIGS. 8 and 9 are views showing modifications of the second embodiment, and FIG. FIG. 10 is a Hg cut-off characteristic diagram of the high frequency filter in each of the above embodiments. Explanation of symbols 10... Gauging, 20... Connector, 32a
~36a, 32b ~36b---Wiring pattern, 40
,50.60...Electronic element, 7o,80...High frequency filter, 72...Insulating layer, 73-77.83-87
...Electrode piece, 71.81...Common electrode plate, D...
electronic equipment.

Claims (1)

[Claims] In a high frequency filter interposed between a connection line extending from an external circuit in a conductive casing of an electronic device and an electronic element provided on the surface of a printed circuit board assembled in the conductive casing, this high frequency filter A high frequency filter for electronic equipment, characterized in that a grounding electrode is directly connected to an inner wall portion of the conductive casing.