US 2004/0201318 A1Published application

Latching relay with switch bar

AssigneeAgilent Technologies, Inc.

InventorMarvin Glen Wong

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Abstract

An electrical relay that uses a conducting liquid in the switching mechanism. In the relay, a pair of switching contacts is attached to the free end of a switch bar and positioned between a pair of fixed electrical contact pads. A surface of each contact supports a droplet of a conducting liquid, such as a liquid metal. A piezoelectric actuator is energized to push or pull the switch bar and move the pair of switching contacts, closing the gap between one of the fixed contact pads and one of the switching contacts, thereby causing conducting liquid droplets to coalesce and form an electrical circuit. At the same time, the gap between the other fixed contact pad and the other switching contact is increased, causing conducting liquid droplets to separate and break an electrical circuit. The piezoelectric actuator is then de-energized and the switching 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 contact pads, each attached to the relay housing in the switching cavity and having a wettable surface;
first and second switching contacts positioned between the first and second fixed contact pads, each of the first and second switching contacts having a wettable surface;
a first conducting liquid volume in wetted contact with the first switching contact and the first fixed contact pad;
a second conducting liquid volume in wetted contact with the second switching contact and the second fixed contact pad;
and
a switch bar having a fixed end coupled to the relay housing and a free end supporting the first and second switching contacts;
a piezoelectric actuator coupled to the relay housing and to the switch bar between its free end and its fixed end, the piezoelectric actuator being deformable in an extensional mode to move the free end of the switch bar in a first direction, to decrease the distance between the first switching contact and the first fixed contact pad and increase the distance between the second switching contact and the second fixed contact pad, and a second direction to increase the distance between the first switching contact and the first fixed contact pad and decrease the distance between the second switching contact and the second fixed contact pad,
wherein:
motion of the switch bar in the first direction causes the first conducting liquid volume to form a connection between the first switching contact and the first fixed contact pad and causes the second conducting liquid volume to separate into two droplets, thereby breaking a connection between the second switching contact and the second fixed contact pad;
and
motion of the switch bar in the second direction causes the first conducting liquid volume to separate into two droplets, thereby breaking the connection between the first switching contact and the first fixed contact pad and causes the second conducting liquid volume to form a connection between the second switching contact and the second fixed contact pad.

9 more elements

A method for switching between a first electrical circuit, between a first switching contact and a first fixed contact pad, and a second electrical circuit, between a second switching contact and a second fixed contact pad, in a relay, the relay including a switch bar 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 contact pads, the method comprising:

if the first electrical circuit is to be selected:
energizing a piezoelectric actuator to push the switch bar in a first direction, thereby moving the first switching contact towards the first fixed contact pad so that a first conducting liquid volume, supported by at least one of the first switching contact and the first fixed contact pad, wets between the first switching contact and the first fixed contact pad and completes the first electrical circuit;
and
if the second electrical circuit is to be selected:
energizing the piezoelectric actuator to pull the switch bar in a second direction, thereby moving the second switching contact towards the second fixed contact pad so that a second conducting liquid volume, supported by at least one of the second switching contact and the second fixed contact pad, wets between the second switching contact and the second fixed contact pad and completes the second electrical circuit.

2 more elements

Dependencies are inferred from the claim text.