초록 ▼

A device for detecting the position of a human finger or other object on a touch-sensitive scrolling pad. Dual independent oscillators may be used to generate two pulse trains at frequencies dependent upon the capacitance of two conductors resulting from the position of the finger on the conductors.

A device for detecting the position of a human finger or other object on a touch-sensitive scrolling pad. Dual independent oscillators may be used to generate two pulse trains at frequencies dependent upon the capacitance of two conductors resulting from the position of the finger on the conductors. The pulses from each oscillator may be counted over a time interval. A ratio-metric measurement may be taken by calculating the ratio of the two counts, and a sum may also be calculated. The ratio of the two counts relates to finger position on the device, and their sum relates to finger pressure upon the device.

대표청구항 ▼

What is claimed is: 1. A device for measuring a position of a pointing member, comprising: a first capacitive node and a second capacitive node each commonly coupled to an input node of a first oscillator having a first variable output frequency; a third capacitive node and a fourth capacitive node

What is claimed is: 1. A device for measuring a position of a pointing member, comprising: a first capacitive node and a second capacitive node each commonly coupled to an input node of a first oscillator having a first variable output frequency; a third capacitive node and a fourth capacitive node each commonly coupled to an input node of a second oscillator having a second variable output frequency, the first, second, third, and fourth capacitive nodes configured to be adjacent and interdigitated; and an insulating material including a groove and a plurality of button depressions adjacent to the groove formed therein, wherein the insulating material is disposed over the first, second, third and fourth capacitive nodes. 2. The device of claim 1, further including: a fifth capacitive node and a sixth capacitive node each commonly coupled to the input node of the first oscillator; and a seventh capacitive node and an eighth capacitive node each commonly coupled to the input node of the second oscillator, the first, second, third, fourth, fifth, sixth, seventh, and eighth capacitive nodes configured to be interdigitated. 3. The device of claim 1, wherein the first, second, third, and fourth capacitive nodes each comprises an etched conductive tracing on a substrate. 4. The device of claim 1, wherein each of the first, second, third, and fourth capacitive nodes are substantially wedge shaped. 5. The device of claim 1, wherein each of the first, second, third, and fourth capacitive nodes extend in an axial direction and are interdigitated with each other in the following order along a direction perpendicular to the axial direction: first capacitive node, then third capacitive node, then second capacitive node, then fourth capacitive node. 6. The device of claim 1, wherein the first and second oscillators are each configured to be disabled while the other oscillator is enabled. 7. A device for measuring a position of a pointing member, comprising: a first even plurality of capacitive nodes each commonly coupled to an input node of a first oscillator having a first variable output frequency; and a second even plurality of capacitive nodes interdigitated with the first even plurality of capacitive nodes, the second even plurality of capacitive nodes each commonly coupled to an input node of a second oscillator having a second variable output frequency; wherein measuring the position of the pointing member at least includes evaluating a ratio of the first and second variable output frequency. 8. The device of claim 1, wherein measuring the position of the pointing member includes evaluating a ratio and a sum of the first and second variable output frequencies, wherein the position of the pointing member is indicated by the evaluated ratio and a pressure imparted by the pointing member indicated by the evaluated sum.