Low EMI capacitive trackpad
First Claim
Patent Images
1. A trackpad printed circuit board, comprising:
- a first layer having a first plurality of metal surfaces forming columns of capacitor plates and a second plurality of metal surfaces electrically isolated from, and interposed between, each pair of the first plurality of metal surfaces;
a second layer having a third plurality of metal surfaces forming rows of capacitor plates that are aligned substantially orthogonal to the first plurality of metal surfaces, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces and a fifth plurality of metal surfaces forming capacitor plate regions that are electrically isolated from the third and fourth plurality of metal surfaces and, further, substantially aligned over the first plurality of metal surfaces on the first layer; and
vias for electrically coupling the second plurality of metal surfaces on the first layer to the fourth plurality of metal surfaces on the second layer.
2 Assignments
0 Petitions
Accused Products
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
32 Claims
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1. A trackpad printed circuit board, comprising:
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a first layer having a first plurality of metal surfaces forming columns of capacitor plates and a second plurality of metal surfaces electrically isolated from, and interposed between, each pair of the first plurality of metal surfaces; a second layer having a third plurality of metal surfaces forming rows of capacitor plates that are aligned substantially orthogonal to the first plurality of metal surfaces, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces and a fifth plurality of metal surfaces forming capacitor plate regions that are electrically isolated from the third and fourth plurality of metal surfaces and, further, substantially aligned over the first plurality of metal surfaces on the first layer; and vias for electrically coupling the second plurality of metal surfaces on the first layer to the fourth plurality of metal surfaces on the second layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A trackpad printed 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; a second layer having a third plurality of metal surfaces aligned substantially orthogonal to the first plurality of metal surfaces, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces and a fifth plurality of metal surfaces electrically isolated from the third and fourth plurality of metal surfaces and, further, substantially aligned over the first plurality of metal surfaces on the first layer; and means for electrically coupling the second plurality of metal surfaces on the first layer to the fourth plurality of metal surfaces on the second layer. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method to fabricate a trackpad printed circuit board, comprising:
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forming, on a first surface of the printed circuit board, 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; forming, on a second surface of the printed circuit board, a third plurality of metal surfaces aligned substantially orthogonal to the first plurality of metal surfaces on the first surface, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces and a fifth plurality of metal surfaces electrically isolated from the third and fourth plurality of metal surfaces and, further, substantially aligned over the first plurality of metal surfaces on the first surface; and forming an electrically conductive path between the second plurality of metal surfaces on the first surface and the fourth plurality of metal surfaces on the second surface. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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30. A computer system comprising:
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a display unit adapted to display a cursor; a central processor operatively coupled to the display unit; and a trackpad operatively coupled to the display unit for controlling the cursor'"'"'s location, the trackpad 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, a second layer having a third plurality of metal surfaces aligned substantially orthogonal to the first plurality of metal surfaces, a fourth plurality of metal surfaces electrically isolated from, and interposed between, each pair of the third plurality of metal surfaces and a fifth plurality of metal surfaces electrically isolated from the third and fourth plurality of metal surfaces and, further, substantially aligned over the first plurality of metal surfaces on the first layer, and means for electrically coupling the second plurality of metal surfaces on the first layer to the fourth plurality of metal surfaces on the second layer. - View Dependent Claims (31, 32)
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Specification