US 2004/0201315 A1Published application

Bending-mode latching relay

AssigneeAgilent Technologies, Inc.

InventorMarvin Glenn Wong

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Abstract

An electrical relay that uses a conducting liquid in the switching mechanism. In the relay, a pair of moveable electrical contacts is attached to the free end of a piezoelectric actuator and positioned between pair of fixed electrical contacts. The contacts each support a droplet of a conducting liquid, such as a liquid metal. The piezoelectric actuator is energized to deform in a bending mode and move the pair of moveable contacts, closing the gap between one of the fixed contacts and one of the moveable contacts, thereby causing conducting liquid droplets to coalesce and form an electrical circuit. At the same time, the gap between the other fixed contact and the other moveable contact is increased, thereby causing conducting liquid droplets to separate and break an electrical circuit. The piezoelectric actuator is then de-energized and the moveable electrical contacts return to their starting positions. The volume of liquid metal is chosen so that liquid metal droplets remain coalesced or separated because of surface tension in the liquid. The relay is amenable to manufacture by micro-machining techniques.

Claims13

Dependent claims

An electrical relay comprising:

a relay housing containing a switching cavity;
first and second fixed electrical contacts attached to the relay housing in the switching cavity each having a wettable surface;
first and second moveable electrical contacts positioned between the first and second fixed electrical contacts, the first and second moveable electrical contacts, each having a wettable surface;
a first conducting liquid volume in wetted contact with the first moveable electrical contact and the first fixed electrical contact;
a second conducting liquid volume in wetted contact with the second moveable electrical contact and the second fixed electrical contact;
and
a piezoelectric actuator in a rest position having fixed end attached to the relay housing and a free end supporting the first and second moveable electrical contacts, the piezoelectric actuator being operable to move the free end in a first direction, to reduce the distance between the first moveable electrical contact and the first fixed electrical contact and increase the distance between the second moveable electrical contact and the second fixed electrical contact, and in a second direction to increase the distance between the first moveable electrical contact and the first fixed electrical contact and decrease the distance between the second moveable electrical contact and the second fixed electrical contact,
wherein:
motion of the free end of the piezoelectric actuator in the first direction causes the first conducting liquid volume to form a connection between the first moveable electrical contact and the first fixed electrical contact and breaks a connection formed by the second conducting liquid volume between the second moveable electrical contact and the second fixed electrical contact;
and
motion of the free end of the piezoelectric actuator in the second direction breaks the connection formed by the first conducting liquid volume between the first moveable electrical contact and the first fixed electrical contact and causes the second conducting liquid to form a connection between the second moveable electrical contact and the second fixed electrical contact.

8 more elements

A method for switching between a first electrical circuit, between a first movable contact and a first fixed contact, and a second electrical circuit, between a second moveable contact and a second fixed contact, in a relay, the relay including a piezoelectric actuator having a fixed end attached to the relay and a free end supporting the first and second switching contacts between the first and second fixed contacts, the method comprising:

if the first electrical circuit is to be selected:
energizing the piezoelectric actuator to deform in a bending mode and move the free end of the piezoelectric actuator in a first direction, thereby moving the first moveable contact towards the first fixed contact so that a first conducting liquid, supported by at least one of the first moveable contact and the first fixed contact, wets between the first moveable contact and the first fixed contact and completes the first electrical circuit;
and
if the second electrical circuit is to be selected:
energizing the piezoelectric actuator to deform in a bending mode and move the free end of the piezoelectric actuator in a second direction, thereby moving the second moveable contact towards the second fixed contact so that a second conducting liquid, supported by at least one of the second moveable contact and the second fixed contact, wets between the second moveable contact and the second fixed contact and completes the second electrical circuit.

2 more elements

Dependencies are inferred from the claim text.