Slide pad membrane

1. A slide pad membrane comprising:

an annular ring having an inner edge;

a center portion having an outer edge; and

a plurality of concentric annular ripples including an outer annular ripple connected to the inner edge of the annular ring and an inner annular ripple connected to the outer edge of the center portion, wherein the plurality of concentric annular ripples is configured to allow the center portion to move in a direction toward the annular ring and wherein the plurality of concentric annular ripples forms a radial spring to bias the center portion toward a center of the annular ring.

2. The slide pad membrane of claim 1 wherein the plurality of concentric annular ripples is configured to allow the center portion to move in a direction orthogonal to a plane that includes the annular ring.

3. The slide pad membrane of claim 1 wherein the annular ring, the center portion, and the plurality of concentric annular ripples are integrally formed.

4. The slide pad membrane of claim 1 wherein the annular ring, the center portion, and the plurality of concentric annular ripples have a substantially uniform composition.

5. The slide pad membrane of claim 1 wherein the annular ring includes an O-ring configured to interface with a case portion.

6. The slide pad membrane of claim 1 wherein the center portion is substantially circular.

7. The slide pad membrane of claim 1 wherein the center portion of the slide pad membrane forms a cavity for interfacing a button.

8. The slide pad membrane of claim 1 wherein the center portion of the slide pad membrane forms a cavity for interfacing a guide structure.

9. The slide pad membrane of claim 1 wherein each of the plurality of concentric annular ripples has a cross-section that is one of substantially sinusoidal, substantially triangular, and substantially square.

10. A slide pad system comprising:

a printed circuit board;

a button; and

a slide pad membrane including an annular ring having an inner edge, a center portion having an outer edge, and a plurality of concentric annular ripples including an outer annular ripple connected to the inner edge of the annular ring and an inner annular ripple connected to the outer edge of the center portion;

wherein the center portion of the slide pad membrane forms a first cavity that includes the button and is configured to move the button relative to the printed circuit board; and

wherein the plurality of concentric annular ripples is configured to allow the center portion to move in a direction toward the annular ring and wherein the plurality of concentric annular ripples forms a radial spring to bias the center portion toward a center of the annular ring.

11. The system of claim 10 further comprising:

a guide ring that forms a second cavity that includes the button;

wherein the first cavity includes the guide ring.

12. The system of claim 11 further comprising:

a dome switch that interfaces with the button.

13. The system of claim 11 further comprising:

a spring attached to the guide ring.

14. The system of claim 13 further comprising:

an electrical connection between the printed circuit board and the spring.

15. The system of claim 11 wherein the printed circuit board includes control circuitry configured to control a pointer in a display in response to motion of the button relative to the printed circuit board.

16. An apparatus comprising:

a slide pad membrane including an annular ring having an inner edge configured to interface with the case, a center portion having an outer edge, and a plurality of concentric annular ripples including an outer annular ripple connected to the inner edge of the annular ring and an inner annular ripple connected to the outer edge of the center portion, wherein the plurality of concentric annular ripples is configured to allow the center portion to move in a direction toward the annular ring and wherein the plurality of concentric annular ripples forms a radial spring to bias the center portion toward a center of the annular ring; and

a case configured to house the slide pad membrane, wherein the case is configured to interface with the annular ring.

17. The apparatus of claim 16 further comprising:

a display device housed in the case and configured to display a pointer;

a slide pad system that includes the slide pad membrane and configured to cause the pointer to move within the display device in response to the center portion being moved in a direction toward the annular ring.

18. The apparatus of claim 16 wherein the case is configured to secure the annular ring to allow the center portion to move in a direction toward the annular ring.

19. The slide pad membrane of claim 1 wherein the radial spring is radially symmetric.