Patent ID: 7971481

Claim:
A circuit for conveying signals, the circuit comprising: a substrate having a circuit end, a sensor end, and an elongated body extending therebetween, the substrate being configured to extend between a first ink level sensor positioned in a first ink reservoir and a circuit displaced from the first ink reservoir; a first, a second, and a third conductive signal trace positioned in the substrate extending between the circuit end and the sensor end, the circuit end being configured to electrically connect the first, the second, and the third signal traces to the circuit; the sensor end including a top layer and a bottom layer, the first signal trace being routed at least partially in the bottom layer and the second and the third signal traces being routed at least partially in the top layer; the sensor end including a first, a second, and a third connector each extending through the top and the bottom layers, the first connector being electrically connected to the first signal trace in the bottom layer, the second connector and the third connector being electrically connected to the second signal trace and the third signal trace, respectively, in the top layer, the first connector, the second connector, and the third connector being configured for electrical connection to a first probe, a second probe, and a third probe, respectively, of the level sensor; and a first ground trace in the sensor end, the first ground trace including a first continuous guard ring in the top layer of the sensor end completely surrounding and spaced from the first connector in the top layer, and a first segmented guard ring in the bottom layer, the first segmented guard ring including a plurality of segments, each segment in the plurality being electrically connected to the first continuous guard ring in the top layer and being spaced from the other segments in the first segmented guard ring, the first signal trace being routed in the bottom layer to the first connector via a space between the segments of the first segmented guard ring.