Low EMI capacitive trackpad
First Claim
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1. A touch sensor circuit board, comprising:
- a first layer having a first plurality of metal surfaces and a second plurality of metal surfaces electrically isolated from, and interposed between, each pair of the first plurality of metal surfaces, wherein each of the first plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the second plurality of metal surfaces are electrically coupled to each other; and
a second layer having a third plurality of metal surfaces that are aligned substantially orthogonal to the first plurality of metal surfaces and a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces, wherein each of the third plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the fourth plurality of metal surfaces are electrically coupled to each other.
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Abstract
A printed circuit board (PCB) assembly provides a two layer capacitive trackpad sensor in which an EMI ground grid is interposed among the sensor'"'"'s capacitive elements on each of its layers. The EMI grid on each of the two layers is electrically coupled via, typically, vias. The described arrangement of sensor elements (capacitor plates) and EMI ground grid traces may be incorporated into a PCB having additional layers (e.g., a four, six or eight layer PCB). If used in this manner, additional vias are provided on the PCB which permit electrical coupling between these “additional layers” and which are electrically isolated from, and shielded by, the EMI ground grid.
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Citations
26 Claims
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1. A touch sensor circuit board, comprising:
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a first layer having a first plurality of metal surfaces and a second plurality of metal surfaces electrically isolated from, and interposed between, each pair of the first plurality of metal surfaces, wherein each of the first plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the second plurality of metal surfaces are electrically coupled to each other; and a second layer having a third plurality of metal surfaces that are aligned substantially orthogonal to the first plurality of metal surfaces and a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces, wherein each of the third plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the fourth plurality of metal surfaces are electrically coupled to each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method to fabricate a touch sensor circuit board, comprising:
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forming, on a first surface of a substrate, a first plurality of metal surfaces; forming, on the first surface, a second plurality of metal surfaces electrically isolated from, and interposed between, each pair of the first plurality of metal surfaces, wherein each of the first plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the second plurality of metal surfaces are electrically coupled to each other forming, on a second surface of the substrate, a third plurality of metal surfaces that are aligned substantially orthogonal to the first plurality of metal surfaces; and forming, on the second surface, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces, wherein each of the third plurality of metal surfaces are electrically isolated from each other and, further, wherein each of the fourth plurality of metal surfaces are electrically coupled to each other. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification