Method and apparatus for finger position tracking and haptic display using conductive islands

A haptic device comprising:

• a surface haptic display comprising a front surface;
• a plurality of conductive islands disposed at a depth in close proximity to the front surface, and wherein each of the plurality of conductive islands are conductively isolated;
• a first conductive trace operatively connected to the surface haptic display, wherein the first conductive trace includes a plurality of first rows;
• a second conductive trace operatively connected to the surface haptic display, wherein the second conductive trace includes a plurality of second rows;
• wherein the plurality of first rows of the first conductive trace and the plurality of second rows of the second conductive trace are interdigitated;
• a control device configured to apply positive voltage signals to one of the first conductive trace and the second conductive trace and to apply negative voltage signals to another of the first conductive trace and second conductive trace;
• and
• wherein an attractive electrostatic force is generated on a fingertip contiguous with the front surface that increases a perceived friction force on the fingertip against movement of the fingertip parallel to the front surface when at least one of the conductive islands that is disposed in an area under the fingertip is charged via a capacitive coupling to the first conductive trace and at least another of the conductive islands that is disposed in the area under the fingertip is charged via capacitive coupling to the second conductive trace.

A method of generating haptic feedback on a surface haptic display, the method including the steps of:

• disposing a plurality of conductive islands at a first depth in close proximity to a front surface;
• conductively isolating each of the plurality of conductive islands;
• disposing a plurality of first conductive traces and second conductive traces at a second depth, wherein a first set of conductive islands is substantially capacitively coupled to the first conductive traces and a second set of conductive islands is substantially capacitively coupled to the second conductive traces;
• generating an attractive electrostatic force on a fingertip contiguous with the front surface;
• and
• charging at least one adjacent pair of conductive islands disposed in an area under the fingertip via a capacitive coupling to the first conductive trace and second conductive trace and wherein the attractive electrostatic force on the fingertip contiguous with the front surface increases a perceived friction force on the fingertip against movement of the fingertip parallel to the front surface;
• and
• enhancing an electrostatic attraction of the fingertip to the at least one adjacent pair of conductive islands in the area under the fingertip by applying one of a positive voltage signal and a negative voltage signal to the first conductive trace and another of the positive voltage signal and the negative voltage signal to the second conductive trace.