JPS637651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compact relay, and particularly to a relay that performs thermal switching control.

[Conventional technology and its drawbacks]

An ideal miniature relay would be small in size, reliable in operation, and low in manufacturing cost. However, in the past, it has been difficult to achieve these three design goals. piezoelectric type,
Various miniature relays have been proposed, including those that utilize electrostatically deflecting beams, those that utilize thermally deflectable beams, and those that utilize the magnetic effect of printed coils. In these, planar manufacturing techniques are utilized to the fullest in order to minimize manufacturing costs and reduce size.

The main drawback of this technique is that reliable operation is difficult to achieve. In fact, reliability is limited due to the small forces generated at the switch contacts. However, in the prior art, it has been difficult to obtain good contact force.

[Purpose of the invention]

An object of the present invention is to provide a small, low-cost, and highly reliable relay.

[Summary of the invention]

The present invention provides a miniature relay that is thermomagnetically actuated. According to a preferred embodiment of the present invention, an insulating substrate having fixed contacts is provided on a plate-shaped magnetic body. A movable contact that pairs with the fixed contact is provided on the movable member. This movable member is magnetically held by a magnetic circuit including a plate-shaped magnetic body and a movable member on an insulating substrate, and pivots in response to changes in magnetic flux density. A heater, which is a heating means on an insulating substrate, is used to control the temperature of a fixed ferromagnetic member. The ferromagnetic member changes magnetic flux density when power is supplied to the heater. This change in magnetic flux density causes the movable member to pivot, thereby effecting the desired opening and closing motion. The magnetic force provides good switch contact force to enable latching action. The use of permanent magnets simplifies design and manufacture as magnetic coils are not required.

〔Example〕

Embodiments of the present invention make full use of the properties of ferromagnetic materials shown in the graph of FIG. As shown in this graph, the saturation magnetic flux density (B-sat) of a ferromagnetic material generally decreases as the temperature increases. The illustrated curves are common to many materials, but are particularly representative of the properties of nickel-iron alloys (NiFe). The magnetic flux density can be freely controlled by heating the ferromagnetic material. In an embodiment, this characteristic controls the magnetic flux in the gap, thereby controlling the magnetic force, and actuating the movable member to close the switch as required.

FIG. 2 shows an embodiment of the present invention. Insulating substrate 2
04 is supported by the plate-shaped magnetic body 202. For example, the plate-shaped magnetic material 202 is made of Alnico 5-7, and the insulating substrate 204 is made of Forsterite. The insulating substrate 204 may be made of other materials, but from the viewpoint of energy efficiency of the relay, it is preferable that the insulating substrate 204 has low thermal conductivity.
Dielectric constant (preferably comparable to magnesia olivine) and printing compatibility are also important factors in material selection.

Ferromagnetic members 206 and 2 are placed on the insulating substrate 204.
08 is placed. In the preferred embodiment, these ferromagnetic members 206 and 208 are attached to the insulating substrate 20.
4 is heated by a thick film resistor (not shown) printed on it. Ferromagnetic members 206 and 208 are formed from a ferromagnetic material, such as a NiFe alloy, and are adhered to the substrate with a high thermal conductivity epoxy adhesive. NiFe alloys are known for their high saturation magnetic flux density and low Curie point temperature. Of course, other materials may be used as long as they have similar characteristics. Chemical milling may be used to form the NiFe elements.

The movable member 210 is attached to the insulating substrate 2 by the magnetic attractive force between the movable member 210 and the plate-shaped magnetic body 202.
04 magnetically held. The movable member 210 is preferably formed of a material having high magnetic permeability and high saturation magnetic flux characteristics that is compatible with plating processing and can be processed with high dimensional accuracy. A 30% NiFe alloy is preferred. Forming the movable member 210 with this material requires high pressure, but it requires a closed die coining process (closed die coining process).
diecoining) can be used. Alternatively, powder metallurgy techniques may be used with the die, although the subsequent plating step is somewhat more difficult.

Movable contacts 212 and 214 are plated on the movable member 210 for contacting fixed contacts 216 and 218 on the insulating substrate. Pivot point 2
20 serves as a fulcrum for the pivoting movement of the movable member 210. A pair of protrusions provided approximately at the center of the insulating substrate sandwich a pivot point 220 as shown in FIGS. 2 and 3. The movable member 210 can swing around an axis parallel to the insulating substrate.

In operation of the relay, the rigid movable member 210 swings from one side to the other about a pivot point. Assuming that the relay is now in the state shown in FIG. 2, the relay operates by supplying current to the ferromagnetic member 206 with a heater (thick film resistor) placed underneath. As the temperature of the ferromagnetic member 206 increases, the saturation magnetic flux decreases according to the graph of FIG. Thus, the magnetic flux in the air gap between ferromagnetic member 206 and one end of movable member 210 is reduced, thereby reducing the force that forces movable contact 212 and fixed contact 216 into contact with each other. On the other hand, since the ferromagnetic member 208 is not heated at this time, it maintains a high saturation magnetic flux density. Therefore, as the temperature of the ferromagnetic member 206 increases, the force of attraction between the ferromagnetic member 206 and one end of the movable member eventually becomes smaller than the force of attraction between the ferromagnetic member 208 and the other end of the movable member. I get tired. At this point, the movable member 210 begins to swing about the pivot point 220, and the movable contact 212 and the fixed contact 2
16 is an open contact, a movable contact 214 and a fixed contact 21
8 comes into contact.

The heater is then turned off and movable member 210 remains in that position. In this way, the movable member 2 of the relay
10 is locked in a stable position at both ends of its rocking motion. The holding force is strong and the energy required to switch the relay from one state to the other is low. The ferromagnetic member 208 can restore the original state.

FIG. 3 shows a perspective view of an embodiment of the present invention. Elements in this figure correspond to elements having the same reference numerals in FIG. This embodiment is suitable for low cost planar manufacturing. It is also possible to reduce the physical shape (dimensions). For example, the third
The dimensions of the insulating substrate in the example shown are approximately
3.8mm x 3.0mm (0.150" x 0.120"), height including permanent magnet and board is approximately 0.15mm
(0.060 inch).

A preferred pad configuration (arrangement) for a relay such as that shown in FIG. 3 is shown in FIG. This figure also shows the electrical connections of the relay. Heaters, represented by resistor symbols 422 and 424, are supplied with control signals, and pads 426, 428, 430, and 432 are supplied with signals to be switched by relays. The switching function of the relay is also diagrammatically shown in block 434.
It is shown by.

It will be obvious to those skilled in the art that various modifications and changes can be made without departing from the spirit of the invention. For example, heater resistors 422 and 424 may be printed directly onto ferromagnetic members 206 and 208. Furthermore, the movable member 210 is configured with a permanent magnet,
The plate-shaped magnetic body 202 may be made of a suitable magnetic material.

〔Effect of the invention〕

According to the present invention, the use of permanent magnets and the thermal properties of ferromagnetic materials eliminates the need for magnetic coils, resulting in a compact and low-cost latch type relay. In addition, a plate-shaped magnetic material is adhered to the surface of the insulating substrate facing the movable member, and a magnetic circuit including the magnetic circuit holds the movable member on the insulating substrate together with a protrusion that pinches the pivot point of the movable member. It has a simple structure that can swing around an axis parallel to the insulating substrate, and this support structure allows the entire relay to be made thin. In addition, a housing or the like is not required, which also provides the advantage of small size and low cost. Also, because it is small, it has good thermal efficiency. Furthermore, since a strong contact holding force determined by the magnetic force of the permanent magnet is obtained, operation reliability is extremely high. Since the electrodes required for the switching operation of the relay only need to be supplied for a short time during switching, power consumption can be reduced. It is also possible to use an insulating substrate larger than the movable member in the present invention, and a desired circuit element that requires the opening/closing action of the contact can be placed near the fixed contact provided on the insulating substrate. By connecting the wire to the contact point, the wire connection can be made very short, which has the effect of improving signal transmission characteristics at high frequencies.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the saturation magnetic flux-temperature characteristic curve of a ferromagnetic material, Fig. 2 is a side view showing an embodiment of the compact relay of the present invention, and Fig. 3 is an embodiment of the compact relay of the present invention. FIG. 4 is a perspective view showing the arrangement of pads for a relay such as that shown in FIG. 3. In the figure, 202 is a plate-shaped magnetic body that is a permanent magnet;
04 is an insulating substrate, 206 and 208 are a pair of ferromagnetic members, 210 is a movable member, 212 and 214
is a movable contact, 216 and 218 are fixed contacts, 42
2 and 424 are heating means.

Claims (1)

[Scope of Claims] 1. An insulating substrate having on one surface a pair of ferromagnetic members and a pair of protrusions approximately in the center between the pair of ferromagnetic members, and on one surface of the insulating substrate. a plurality of fixed contacts provided near the ferromagnetic member; a heating means provided on the insulating substrate for selectively heating the pair of ferromagnetic members; a plate-like magnetic material that is attached to the ferromagnetic member and covers the pair of ferromagnetic members via the insulating substrate; a movable member made of a magnetic material, which is disposed between the pair of protrusions of the insulating substrate, the axis of vibration is parallel to the insulating substrate, and has a plurality of movable contacts at positions opposite to the fixed contacts; Either one of the movable member and the plate-shaped magnetic body is a permanent magnet, and the heating of the ferromagnetic member by the heating means controls opening and closing of the switch consisting of the fixed contact and the movable contact. A small relay characterized by: