JPH0541485Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reed relay, and particularly to a structure of a reed relay that can intermittent extremely small signal currents and can be mounted at high density.

[Prior art and its problems]

Generally, reed relays are used to control small signal currents intermittently. Among these, tubular reed relays are often used to intermittent the measured minute current. This is usually the third
Like the reed relay 101 shown in the figure, a reed switch 103 inserted into a cylindrical electrostatic shield pipe 102 is opened and closed by a coil 105, and a cylindrical magnetic electrostatic A shield case 106 is provided.

The reed relay 101 is characterized by an electrostatic shield pipe 102. That is, reed switch 103
Since there is a significant difference depending on the usage conditions between the magnitude of the current flowing through the signal line 104 connected to the signal line 104 and the magnitude of the excitation current of the coil 105 flowing through the lead wire 107, the electrostatic shield pipe 102 is grounded. This prevents noise and the like based on the current flowing through the lead wire 107 from affecting the signal line 104.

However, in the conventional reed relay 101, the length _L1 of the portion of the electrostatic shield pipe 102 that protrudes from the magnetic electrostatic shield case 106 is extremely large. There are two reasons for this, the first is
In this case, the magnetic electrostatic shielding case 106 is connected to the coil 10.
This is because the shield pipe 102 is not shaped to completely enclose the signal line 104 and the coil 105, so that by making the shield pipe 102 long, the signal line 104 and the coil 105 are separated to prevent induced interference. Second, although it is necessary to maintain a sufficient distance between the signal line 104 and the leader line 107 to prevent induction, the leader line 107
is the opening 106a of the cylindrical shield case 106.
This is because, since the shield pipe 102 extends in parallel with the signal line 104 in the longitudinal direction, it is necessary to maintain a constant distance between the signal line 104 and the lead line 107 by making the shield pipe 102 long.

Therefore, the reed relay 101 with the above structure is
When mounted on a board, a large mounting area is required. Moreover, under the conditions of use where extremely small currents (for example, fA to pA) are controlled intermittently, the shielding between the signal line 104, the coil 105, and the lead wire 107 is still insufficient, and an induced current is induced in the signal line 104. There was a drawback that it ended up happening.

In addition, since the reed relay 101 does not have a shielding plate disposed in the opening 106a of the magnetic electrostatic shielding case 106, and there is a large amount of leakage magnetic flux, there is a risk of malfunction if multiple reed relays are installed in series in close proximity. The drawback was that high-density packaging was not possible.

Furthermore, due to the above drawbacks, when using conventional reed relays to control small currents intermittently,
We had no choice but to take measures such as placing a shielding case over the reed relay mounted on the board or attaching another shielding plate.

In addition to the tubular type reed relay shown in Figure 2, there are also DIP (dual in line package) and SIP (single in line) types.
(package) type, for general printed circuit boards, etc., but in all of these, the signal line and the lead wire of the coil are drawn out in the same direction, and as in the invention of the present application, the signal line and the lead wire are shielded. None of them had a similar external shape.

[Purpose of this invention]

The present invention was developed to eliminate the drawbacks of the prior art described above, and its purpose is to reduce the capacitive coupling between the coil and the signal line, eliminate the effects of noise and excitation current, and extremely The purpose is to enable intermittent control of minute currents. Another object is to enable two or more reed relays to be arranged close to each other in the vertical direction, thereby enabling high-density packaging. Another purpose is to prevent the influence of the excitation current and noise flowing through the lead wires from reaching the signal wires, to allow the lead wires to be attached to a printed circuit board without bending them, and to reduce the mounting area. The aim is to reduce the number of Another object is to make it easier to draw out the lead wire from the bottom surface and to obtain a predetermined shielding effect by using the printed pattern on the printed circuit board on which the relay is mounted as a shield. Another purpose is to reduce the portion of the electrostatic shield pipe that protrudes from the magnetic electrostatic shield case, thereby reducing the size of the relay body.

[Summary of the idea]

In short, the present invention includes a cylindrical electrostatic shield pipe, a reed switch inserted into the electrostatic shield pipe, a signal line connected to a lead piece of the reed switch, and a wire for opening and closing the reed switch. In a reed relay comprising a coil, a leader wire for supplying an excitation current to the coil, and a magnetic electrostatic shielding case provided outside the coil, the magnetic electrostatic shielding case at least A shielding plate made of metal is provided on all surfaces other than the bottom surface of the electrostatic shielding case, and the signal line is drawn out in the longitudinal direction of the electrostatic shielding pipe, and the leader wire is drawn out from the bottom surface. It is characterized by:

[Example of idea]

Hereinafter, the present invention will be explained based on embodiments shown in the drawings. As shown in FIG. 1, a reed relay 1 according to the present invention includes an electrostatic shield pipe 2 made of cylindrical metal, a reed switch 3 inserted into the electrostatic shield pipe, a signal line 4, and a lead. It includes a coil 5 for opening and closing the switch 3, a magnetic electrostatic shielding case 6, and a lead wire 7 for supplying a drive current to the coil 5. The leader line 7 is soldered to a printed pattern 10 on a printed circuit board 9, and a printed pattern 11 is attached to a surface 9a of the printed circuit board 9 facing the reed relay 1.

As shown in FIG. 2, the magnetic electrostatic shielding case 6 includes a box-shaped metal shielding plate 6a, and the bottom surface 6b of the shielding case 6 is made of synthetic resin.

The coil 5 is wound around a bobbin 12, and the bobbin 12 is fitted and fixed to the magnetic electrostatic shielding case 6.

A hole 6d is provided in the side plate 6c of the shield case 6, and the electrostatic shield pipe 2 is inserted into the hole 6d.
The bobbin 12 extends through the bobbin 12 and is supported by the bobbin 12.

Referring again to FIG. 1, there is a gap between the magnetic electrostatic shielding case 6 and the electrostatic shielding pipe 2.
W ₁ is not directly electrically connected to the shield case 6 and the shield pipe 2, and a ground wire (not shown) is connected to each of the shield case 6 and the shield pipe 2. 2 can be grounded to any potential.

The reed switch 3 includes reed pieces 14A and 14B sealed together with an inert gas in a glass tube 13, and the reed pieces 14A and 14B are connected to a signal line 4, which is connected to a filler 15. The electrostatic shield pipe 2 is supported and pulled out in the longitudinal direction of the electrostatic shield pipe 2.

The printed pattern 11 is adhered in a flat plate shape facing the bottom surface 6b, and is grounded to serve as a shield against the lower side of the reed relay 1.

The present invention is constructed as described above, and its operation will be explained below. Reed relay 1 is
As with a normal reed relay, when an excitation current is supplied to the lead wire 7, the magnetic field generated by the coil 5 attracts the lead pieces 14A and 14B, and the signal wire 4
becomes conductive.

At this time, since the electrostatic shield pipe 2 and the side plate 6c of the shield case 6 are present between the coil 5 and the signal line 4, the influence of the excitation current and noise of the coil 5 is reduced by the shielding effect of both. This prevents the signal from reaching the signal line 4. Furthermore, since the magnetic lines of force generated by the coil 5 are prevented from leaking in the direction of the arrow A by the magnetic electrostatic shielding case 6, the reed relays 1 can be mounted in tandem in the direction of the arrow A. Furthermore, even if the shield case 6 and the shield pipe 2 are not directly electrically connected,
If the width of the gap _W1 is equal to or less than a certain value, a predetermined shielding effect can be obtained, so that the reed relay 1 can be easily assembled and manufactured.

In addition, since the leader line 7 extends downward from the bottom surface 6b, the printed circuit board 9 can be connected without going through the step of bending the legs.
Since the signal line 4 and the leader line 7 are shielded by the flat printed pattern 11, the influence of the excitation current flowing through the leader line 7 and noise on the signal line 4 is eliminated. Furthermore, the printed pattern 11 also shields the magnetic field of the coil 5. Therefore, there is no need to use metal for the bottom surface 6b, and the printed pattern 11, which is easy to manufacture, can be used instead, so that the shape in which the leader line 7 is drawn out from the bottom surface 6b can be manufactured very easily.

Furthermore, as described above, the shielding case 6 eliminates inductive interference to the signal line 4, so even if the length _L2 of the portion of the shielding pipe 2 protruding from the shielding case 6 is short, sufficient shielding can be achieved. will be done.

In the above embodiment, the bottom surface 6b of the magnetic electrostatic shielding case 6 is made of synthetic resin, but is not limited to this, and may be made of metal like the shielding plate 6a. In that case, there is no need to provide the printed pattern 11. Further, in the above embodiment, the magnetic electrostatic shielding case 6 and the electrostatic shielding pipe 2 are described as not being in direct contact with each other, but of course they may be directly electrically connected. In that case, the two ground wires (not shown) connected to each of the two can be shared by one.

[Effects of this invention]

Since the present invention is constructed and operates as described above, the magnetic electrostatic shielding case of the tubular reed relay is formed in the shape of a housing, so that capacitive coupling between the coil and the signal line is reduced. The effects of noise and excitation current are eliminated, and the effect of enabling extremely small intermittent control of current is obtained. In addition, since the magnetic electrostatic shield case is equipped with a shielding plate that shields longitudinal lines of magnetic force, two or more reed relays can be placed close to each other in the vertical direction.
The effect of enabling high-density packaging is obtained. In addition, since the leader wire that supplies the excitation current to the coil is drawn out from the bottom of the magnetic electrostatic shielding case, the influence of the excitation current flowing through the leader wire and noise is prevented from reaching the signal line. It can be attached to a printed circuit board without bending, and the mounting area can be reduced. In addition, since the bottom of the magnetic electrostatic shield case is made of synthetic resin, by using the printed pattern on the printed circuit board on which the relay is mounted as a shield, it is easy to pull out the leader wire from the bottom, and the specified shield can be used as a shield. There is an effect that can be obtained. Further, due to the above-mentioned effects, the portion of the electrostatic shield pipe that protrudes from the magnetic electrostatic shield pipe becomes extremely short, so that the relay body can be miniaturized. In addition, the magnetic electrostatic shield case and the electrostatic shield pipe are not in direct contact and can be grounded to any potential, so the electrostatic shield pipe can be used as a guard electrode with approximately the same potential as the signal line. It is possible to prevent leakage current from flowing through the surface or inside of an insulating material such as a filler or a bobbin from the signal line.

[Brief explanation of the drawing]

1 and 2 relate to an embodiment of the present invention; FIG. 1 is a side sectional view showing a reed relay mounted on a board; FIG. 2 is an exploded perspective view of the reed relay;
FIG. 3 is a side sectional view showing a conventional reed relay mounted on a board. 1,101...Reed relay, 2,102...
Electrostatic shield pipe, 3,103... Reed switch, 4,104... Signal line, 5,105... Coil, 6,106... Magnetic electrostatic shield case,
6a...shielding plate, 6b...bottom surface, 6c...side plate,
7,107...This is a leader line.

Claims (1)

[Claims for Utility Model Registration] 1. A cylindrical electrostatic shield pipe 2 and a reed switch 3 inserted into the electrostatic shield pipe 2.
and the lead pieces 14A, 14 of the reed switch.
A signal line 4 connected to B and drawn out from the mouth of the electrostatic shield pipe 2, a coil 5 for opening and closing the reed switch, and a leader line 7 for supplying excitation current to the coil 5.
and a magnetic electrostatic shielding case 6 provided on the outside of the coil 5, 1. The length of the electrostatic shielding pipe 2 is equal to or longer than the length of the magnetic electrostatic shielding case 6. The magnetic electrostatic shielding case 6 includes shielding plates 6a on all surfaces other than the bottom surface 6b of the magnetic electrostatic shielding case, and the electrostatic shielding pipe 2 is provided on the side plate 6c of the shielding plate 6a. A hole 6d is provided surrounding the electrostatic shield pipe 2, and the electrostatic shield pipe 2 and the magnetic electrostatic shield case 6 are in direct contact between the hole 6d and the electrostatic shield pipe 2. A reed relay 1 characterized in that there is a gap W ₁ to prevent this from occurring, and the lead wire 7 is drawn out from the bottom surface 6b. 2 The magnetic electrostatic shielding case 6 has a bottom surface 6b.
The reed relay 1 according to claim 1, wherein the reed relay 1 is made of an insulator. 3. The reed relay 1 according to claim 2, wherein the insulator is made of synthetic resin. 4. The reed relay according to claim 1, wherein the magnetic electrostatic shielding case has a shielding plate made of the same metal as the other shielding plates on its bottom surface. . 5. Utility model registration claim 1, 2, or 3, characterized in that air is interposed in the gap _W1 as an insulator.
The reed relay according to item 1 or 4. 6. Utility model registration claims 1, 2, or 3, characterized in that the electrostatic shield pipe 2 and the magnetic electrostatic shield case 6 are each connected to a ground wire. The reed relay according to item 4 or item 5.