JPH051140Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is mainly designed to stabilize the potential of the attenuator for oscilloscopes by separating the earth current path even when the input/output current flows into the earth line. The present invention relates to an attenuator grounding structure that provides such characteristics.

[Prior art]

An attenuator, for example a programmable attenuator, usually includes a switching mechanism having a plurality of stages of attenuator units and a relay for switching between the attenuator units and setting an arbitrary attenuation rate. Various parts constituting the attenuator unit and the switching mechanism are mounted on a board such as a printed circuit board, and the board on which the various parts are mounted is housed in a case.

FIG. 11 is a diagram showing a part of a board on which components constituting each part of the attenuator are mounted. As shown in the figure, the board 90 includes a ground pattern 91 continuous from the input side to the output side, and ground patterns 91a to 91 branched from the ground pattern 91.
d is formed. The input/output currents I ₁ to I ₄ from the switching mechanism and attenuator unit forming the attenuator are connected to the ground pattern 91 through the branched ground patterns 91 a to 91 d.
connection 92 electrically connected to the case.
and a case (not shown). In other words, the grounding structure of the conventional attenuator is such that the input/output currents I ₁ to _{I 4} from each part of the attenuator flow into the ground pattern 91 formed continuously from the input side to the output side, and from the ground pattern to the case. It is configured.

There may be a plurality of connecting portions 92, and a metal plate 95 having a U-shaped cross section as shown in FIG. 12 may be inserted into the side of the board 90 to connect the ground pattern 91 to the case.

[Problem that the invention attempts to solve]

However, in the above conventional attenuator grounding structure, there is a limit to lowering the impedance of the grounding pattern 91, and the input/output current from each attenuator unit section passes through the grounding patterns 91a to 91d to this grounding pattern 91.
When all of I ₁ to _{I 4} flow in, the potential within the ground pattern 91 increases, and as a result, the attenuator characteristics exhibit characteristics different from those at the time of design. Further, the potential drop caused by the current I ₁ is much larger than that caused by the current I ₄ , and if the current I ₁ flows into another contact point, the characteristics will change greatly and become an unstable factor. Furthermore, there is a problem in that connecting the entire surface of the ground pattern 91 to the case for grounding increases the cost.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to eliminate the above-mentioned problems and provide an attenuator grounding structure whose characteristics are not disturbed by the input/output currents of various parts of the attenuator.

[Means for solving problems]

In order to solve the above problems, the present invention provides a grounding structure for an attenuator, in which various parts constituting the attenuator are mounted on at least one or more substrates on which various patterns such as a grounding pattern are formed on the surface, and the various parts In an attenuator in which a board on which is mounted is housed in a case, the ground pattern on the surface of the board is separated into a plurality of parts from the input side to the output side, and each of the separated plurality of ground patterns is connected to a ground plate member. The ground plate member was electrically connected to the case, and the ground plate member was electrically connected to the case.

[Effect]

By configuring the grounding structure of the attenuator as described above, the grounding pattern on the board is separated into a plurality of parts from the input side to the output side, and each separated grounding pattern is connected to the grounding plate member via the grounding plate member. Since it is connected to a low case, input and output currents do not mix in areas with high impedance, the potential of the ground pattern does not rise, and the characteristics of the attenuator are stabilized.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 to 4 are diagrams showing an attenuator for an oscilloscope equipped with a grounding structure according to the present invention, in which FIG. 1 is a plan view of a printed circuit board, FIG.
3b is a bottom view and a plan view of the ceramic substrate which is the attenuator unit part, FIG. 3 is a diagram showing the circuit configuration of the entire attenuator including the drive circuit,
FIG. 4 is a diagram showing the circuit configuration of the attenuator unit section. The attenuator shown in this embodiment is a so-called programmable attenuator, and as shown in FIG.
4. Diodes _D1 to _D4 , operating coils 51l to 54l of relays 51 to 54, and the operating coils 51l to 54l.
Capacitor C ₁ to ground 54l at high frequency
C ₄ , transistor that drives relays 51 to 54
Tr ₁ ~ Tr ₄ , AC coupling capacitor C ₁₁ , resistor R ₁ ~
R ₃ and capacitors C ₅ and C ₆ . In addition, the third
In the figure, 61a to 61d are transistors Tr ₁
-Relay drive signal input terminal for external input to drive the relay via Tr ₄ , 61e is a relay ground terminal, and 61f is a relay power supply terminal.

Each component constituting the programmable attenuator is mounted on a printed circuit board 10 as shown in FIG. That is, as shown in the figure, the printed circuit board 1
A plurality of patterns such as ground patterns 11 to 16 separated from the input side to the output side are formed on the top of the transistor Tr ₀ at predetermined locations.
Tr ₄ , resistors R ₁ to _{R 3} , capacitors C ₁ to C ₆ , diodes D ₁ to _{D 4} , and the like are mounted. Also,
The widths of the ground patterns 11, 12, 13, 14 and the ground patterns 15, 16 are made wider than other patterns in order to keep the impedance as low as possible.

Each of the ground patterns 11, 12, 13, 14 is attached to one side of the printed circuit board 10, and the tongue pieces 22a, 22b, 22c,
22d. Further, the grounding plate 22 is a plate-like member made of a metal plate, and is attached to the lower surface of the printed circuit board 10 so as to extend substantially perpendicularly to the lower surface, as shown in FIG. In addition,
The relays 51 to 54 are connected to the printed circuit board 1 as described later.
It is mounted on the bottom surface of 0.

As shown in Fig. 4, the attenuator unit _A1 includes trimmer capacitors 41, 42 and resistors.
Equipped with parts R ₄₁ ~ R ₄₅ , capacitors C ₄₁ and C ₄₂ ,
The components are mounted on a ceramic substrate 40 as shown in FIGS. 2a and 2b (FIG. 2a is a bottom view,
Figure b is a plan view}. That is, the ceramic substrate 4
0 is formed with patterns such as an input side earth pattern 46, output side earth patterns 44, 45 (44, 45 are connected with F-type leads), an output pattern 47, an input pattern 48, etc. The trimmer capacitor 4 is placed at a predetermined position on the board 40.
1, 42, resistor R ₄₁ ~ R ₄₅ , capacitor C ₄₁ , C ₄₂
has been implemented. Attenuator unit A ₂
The circuit configuration is also substantially the same as that in FIG. 4, and each component is mounted on a ceramic substrate as shown in FIGS. 2a and 2b.

The programmable attenuator main body is constructed by arranging the attenuator unit parts _A1 and _A2 at predetermined positions on the printed circuit board 10.

6 is a perspective view of the programmable attenuator main body, FIG. 7 is a view seen from the direction of arrow A in FIG. 6, and FIG. 8 is a view seen from the direction of arrow B in the same figure. As shown in the figure, the bottom surface of a printed circuit board 10 on which various components are mounted as shown in FIG.
An AC coupling capacitor C ₁₁ is installed. At the top of the printed circuit board 10 is an attenuator unit.
Place A ₁ and A ₂ in place. In the figure, 25a,
25b, 26a, 26b are ceramic substrates 4
This is a conductive member made of a thin metal plate that supports the ceramic substrates 0a and 40b on the printed circuit board 10 and electrically connects the ground patterns of the ceramic substrates 40a and 40b to the ground pattern of the printed circuit board 10.

The conductive member 25a has its leading end connected to the output side ground patterns 44 and 45 of the ceramic board 40a by soldering, and its rear end connected to the ground pattern 14 of the printed circuit board 10 by soldering. Further, the leading end of the conductive member 25b is connected to the input side ground pattern 46 of the ceramic board 40 by soldering, and the rear end is connected to the ground pattern 13 of the printed circuit board 10 by soldering.

The conductive member 26a has its leading end connected to the output side ground patterns 44 and 45 of the ceramic board 40b by soldering, and its rear end connected to the ground pattern 12 of the printed circuit board 10 by soldering. Further, the leading end of the conductive member 26b is connected to the input side ground pattern 46 of the ceramic board 40 by soldering, and the rear end is connected to the ground pattern 11 of the printed circuit board 10 by soldering.

Further, the leading end of the conductive member 27a is connected to the output pattern 47 of the ceramic substrate 40 by soldering, and the rear end thereof is connected to the pattern 10a of the printed circuit board 10 by soldering. The conductive member 27b has its tip connected to the input pattern 48 of the ceramic substrate 40.
The rear end is connected to the printed circuit board 10 by soldering.
It is connected to the pattern 10b by soldering.
The conductive member 28a has its tip connected to the ceramic substrate 40.
The rear end is connected to the output pattern 47 of the printed circuit board 10 by soldering. The leading end of the conductive member 28b is connected to the input pattern 48 of the ceramic board 40 by soldering, and the rear end is connected to the pattern 10d of the printed circuit board 10 by soldering. Further, here, conductive members 27a, 27b and 28a, 28b
The ceramic substrate 40 and the printed circuit board 1 are respectively
It also has the effect of supporting above 0.

9a, b, and c are exploded perspective views of a programmable attenuator equipped with the programmable attenuator main body 1 described in detail above. In the figure, 70 is a metal case, and the case 70 includes trimmer capacitors 41, 42 adjustment parts 41a, 4
Trimmer capacitor adjustment holes 71a to 71d are formed for adjusting the trimmer capacitor 2a, and one side is provided with a hole for electrically and mechanically coupling with the ground plate 22 fixed to one side of the printed circuit board 10. Screw holes 72a to 72c are formed, and screw holes 73 for fixing the lid body 80 are formed at the four corners as described later.
a to 73d (73c and 73d are not shown) are formed. Furthermore, an input connector 74 for a coaxial cable is provided at one end of the case 70 to be electrically connected to the input section 20 of the printed circuit board 10.
is fixed.

A metal lid 80 is fitted and fixed to the lower part of the case 70, and screw holes 81a to 81d are formed at the four corners of the lid 80. Further, the printed circuit board 1 is provided on one side of the lid body 80.
An elongated hole 83 is formed through which the relay drive signal input terminals 61a to 61f of 0 pass through, and an insulating member 82 is attached to one end of the insulating member 82 having a through hole formed in the center through which the output terminal 21 passes.

When assembling the programmable attenuator having the above configuration, the printed circuit board 10 is inserted into the case 70 and fixed using fixing means such as screws (not shown). As a result, the trimmer capacitor 41,
The adjustment parts 41a, 42a and 41a, 42a of 42, 41, 42 are fixed at positions corresponding to the trimmer capacitor adjustment holes 71a to 71d of the case 70. Next, the core wire of the input connector 74 is connected to the input section 20 of the printed circuit board 10 using a conductive wire or the like. Next, by passing the screws 84 through the screw holes 72a to 72c and screwing their tips into the screw holes 22f to 22h of the ground plate 22, the ground plate 22 and the case 70 are electrically connected securely as shown in FIG. Connecting.

Next, the lid body 80 is fitted to the lower part of the case 70, and screw holes 73a to 7 formed at the four corners of the case 70 are fitted.
3d, and the tips thereof are screwed into screw holes 81a to 81d formed at the four corners of the lid 80 to fix the lid 80 to the lower part of the case 70. At this time, the relay drive signal input terminal 61a of the printed circuit board 10
~61d and relay power terminals 61e and 61f are
It passes through the long hole 83 of the lid body 80 and is led out to the outside, and the output terminal 21 is also led out to the outside through the hole in the center of the insulating member 82. This completes the assembly of the programmable attenuator. By configuring the programmable attenuator as described above, the ground of the printed circuit board 10 is connected to the ground patterns 11, 12, 13, and 14, which are formed separately from the input side to the output side, on one side of the printed circuit board 10. It is electrically connected to the case 70 via a ground plate 22 attached to the case 70 . Furthermore, the grounding of the ceramic substrates 40a, 40b on which the components constituting the attenuator units _A1 , _A2 are mounted is also conducted by connecting the grounding patterns 44, 45, 46, which are formed separately into a plurality of conductive members 25a, 25b, respectively. 2
It is electrically connected to the ground patterns 14, 13, 12, and 11 of the printed circuit board 10 via the wires 6a and 26b, and to the case 70 via the ground plate 22. Therefore, in the programmable attenuator having the above configuration, the sum of the input and output currents I ₁ to I ₄ is 1, like the conventional attenuator shown in FIG.
Since it does not flow into the ground pattern 91 of the book, which has a high impedance, there is no problem that the potential of the ground pattern 91 increases and the characteristics become unstable. In addition, input and output currents do not mix in the tongues 22a to 22d of the ground plate 22, which have high impedance, and the plate parts 22a to 22d, which have low impedance,
Since they are mixed at e and case 70, the characteristics of the attenuator are improved and stabilized.

Although the above embodiment has been explained using a programmable attenuator as an example, the grounding structure according to the present invention is not limited to this, and it may be difficult if the characteristics are disturbed due to changes in the potential of the grounding pattern of the board. It is effective when used with a strong attenuator.

[Effect of idea]

As explained above, according to the present invention, the ground pattern on the board is formed into a plurality of separate parts from the input side to the output side, and each of the separated ground patterns is connected to a ground with a high impedance via the ground plate member. Since it is connected to a low case, all the input and output currents of each part flow into the high impedance ground pattern and the potential does not rise as in the conventional case, which has the extremely excellent effect of stabilizing the characteristics of the attenuator. It will be done.

[Brief explanation of the drawing]

1 to 4 are diagrams showing a programmable attenuator equipped with a grounding structure according to the present invention, in which FIG. 1 is a plan view of a printed circuit board, FIG. 2 is a bottom view of a ceramic board, and FIG. A plan view, Figure 3 shows the circuit configuration of the entire programmable attenuator, Figure 4 shows the circuit configuration of the attenuator unit, and Figure 5 shows the state in which the ground plate and ground piece are attached to the printed circuit board. 6 is a perspective view of the main body of the programmable attenuator, FIG. 7 is a view seen from the direction of arrow A in FIG. 6, FIG. 8 is a view seen from the direction of arrow B, and FIGS. b, c are exploded perspective views of the programmable attenuator according to the present invention, Fig. 10 is a cross-sectional view showing the state of connection between the ground plate and the ground piece and the case, and Fig. 11
The figure shows part of the board of a conventional attenuator.
FIG. 12 is a diagram showing a member for grounding the entire surface of a conventional ground pattern. In the figure, 1...Programmable attenuator main body, 10...Printed circuit board, 11-16...Earth pattern, 20...Input terminal section, 21...Output terminal, 22...Earth section, 23, 24...Earth Piece, 25a, 25b, 26a, 26b... Conductive member, 40... Ceramic substrate, 51-54... Relay, 61a-61f... Relay drive signal input terminal, 70... Case, 80... Lid, A ₁ , _A2 ...
...Attenuator unit section.

Claims (1)

[Scope of utility model registration request] Various parts constituting the attenuator are mounted on at least one or more boards on which various patterns such as a ground pattern are formed, and the boards on which the various parts are mounted are housed in a conductive case made of metal or the like. In the attenuator, the ground pattern on the surface of the substrate is formed by separating it into a plurality of parts from the input side to the output side, and each of the separated plurality of ground patterns is electrically connected to a ground plate member, and the ground pattern is separated from the input side to the output side. An attenuator ground structure characterized by electrically connecting a plate member to a case.