Yesterday Mark Gurman of 9to5Mac posted a report regarding a 3-level next gen Force Touch interface. I was curious as to whether Apple had ever filed a patent regarding the 3-level aspect of Force Touch before. Our last report on Force Touch titled "Apple's Force Touch for iPhone Invention was Published Today" was derived from a patent discovered in Europe. The report covered Apple's invention that generally related to force sensing and, more particularly, to a temperature compensating force sensor having two or more transparent force-sensitive components separated by a compliant layer. So this morning I went back to the original European patent filing to see if "two or more transparent force-sensitive components" had a definitive third layer to make it 3D. I was pleasantly surprised to find that such a reference to Force Touch existed. No wonder Apple tried to hide this patent in Europe until after it came to life in the new iPhone. If it wasn't for yesterday's 9to5Mac report, I would have missed that aspect of this important invention. The bottom line is that yesterday's revelation actually turns out be fully supported by an Apple patent that was originally filed back in January 2014.

The first patent reference made in Apple's European patent states the following: "Thus, the strain measured directly from the force-sensitive components 512, 522 may be approximated, in one example, as a sum of three components.

Apple Equation 3 noted as: Emeasured = Euser + Epyro + EcTE

Apple's Equation 3: where Emeasured is the strain measurement or estimation, Euser is the strain due to the force of the touch; Epyro is the strain due to the pyroelectric effect; and EcTE is the strain due to the coefficient of thermal expansion.

Apple's patent FIG. 5C depicts a side view of a portion of an example embodiment of a force- sensitive structure of a device. As with FIG. 5A, a plurality of force-sensitive components #512 may be disposed below a first substrate #510, which may receive a force from a force-receiving layer #540.

There may be a first intermediate layer #502 which is positioned above a second substrate #520 which itself may include a plurality of force-sensitive components #522 disposed thereupon. Positioned below the second substrate may be a second intermediate layer. Below the second compliant layer may be disposed a third substrate #530. The third substrate may include a plurality of force-sensitive components #532. Although three layers of substrates are shown, certain embodiments may include additional layers. In many embodiments one or more of the intermediate layers may be made from a compliant material.

For embodiments having this configuration or related layer configurations, temperature may be compensated by determining the temperature gradient between the first, second and third layers. For example, when a user applies a force, a strain may be measured at each of the three layers. As explained above, the measured strain may include unwanted effects of temperature. Accordingly, by measuring the difference between the measured strains of the first, second, and third layers, temperature may be derived and compensated for.

No wonder Apple filed this patent application in Europe and not the US at this time before the invention of 3D Force Touch comes to the iPhone next week.

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