Mobile device accessory equipped to communicate with mobile device
A smartphone case can include one or more piezotransductive materials (e.g., piezoelectric, piezomagnetic, piezoluminescent, etc.) positioned at one or more contact locations of the smartphone case. For example, a piezoelectric material can be positioned at multiple different locations of the smartphone case at which users may physically contact the smartphone case when holding the case. The piezoelectric material can generate an electric charge when pressure is applied to the material, and the generated electric charge can pass through an electromagnetic coil as an electric current to produce a magnetic field which one or more sensors (e.g., one or more magnetometers) of a smartphone that is housed within the smartphone case may be able to detect.
1. A mobile device case comprising:
an inner surface configured to detachably engage an outer surface of a mobile computing device housing;
first and second opposing side walls for engaging respective edges of the mobile computing device housing;
a first plurality of contact locations positioned along the first side wall, each of the first plurality of contact locations including piezoelectric material configured to produce a first electric current in response to application of mechanical stress, the first electric current produced without an external power source;
a second plurality of contact locations positioned along the second side wall, each of the second plurality of contact locations including piezoelectric material configured to produce a second electric current in response to application of mechanical stress, the second electric current produced without an external power source; and
a plurality of electromagnetic coils, each of the plurality of electromagnetic coils in electric communication with the piezoelectric material of a distinct one of the first plurality of contact locations or the second plurality of contact locations, each respective electromagnetic coil of the plurality of electromagnetic coils configured to produce a respective magnetic field in response to receiving the respective electric current produced by the respective piezoelectric material in contact with the respective electromagnetic coil.
2. The mobile device case of claim 1 , wherein the first plurality of contact locations comprises three or more contact locations positioned along the first side wall and the second plurality of contact locations comprises three or more contact locations positioned along the second side wall, wherein the first plurality of contact locations are substantially equidistantly spaced and the second plurality of contact locations are substantially equidistantly spaced.
3. The mobile device case of claim 1 , wherein the piezoelectric material is configured to produce electric charge that increases in voltage as the mechanical stress placed upon the piezoelectric material increases.
4. The mobile device case of claim 1 , wherein the magnetic fields produced by each of the plurality of electromagnetic coils overlap at a particular location when each of the contact locations receives pressure that surpasses a threshold pressure value.
5. A mobile device accessory comprising:
a first inner surface for detachably engaging an outer surface of a mobile computing device housing;
a first piece of piezoelectric material positioned at least partially within the mobile device accessory such that when user input applies pressure to a first outer surface opposite the first inner surface, the first piece of piezoelectric material experiences first mechanical stress and produces a first electric current in response to the first mechanical stress, the first electric current produced without an external power source; and
a first electromagnetic coil that is in electric communication with the first piece of piezoelectric material and that is configured to produce a magnetic field in response to the first electric current produced by the first piece of piezoelectric material;
a second piece of piezoelectric material positioned at least partially within the mobile device accessory such that when user input applies pressure to the mobile device accessory at a location near the second piece of piezoelectric material, the second piece of piezoelectric material experiences second mechanical stress and produces a second electric current in response to the second mechanical stress, the second electric current produced without an external power source; and
a second electromagnetic coil that is in electric communication with the second piece of piezoelectric material and that is configured to produce a magnetic field in response to the second electric current produced by the second piece of piezoelectric material.
6. The mobile device accessory of claim 5 , wherein the first piece of piezoelectric material is configured to produce first electric current that increases in voltage as the first mechanical stress placed upon the piezoelectric material increases.
7. The mobile device accessory of claim 5 , wherein the mobile device accessory is a case for the mobile computing device.
8. The mobile device accessory of claim 5 ,
wherein the first piece of piezoelectric material and the second piece of piezoelectric material are positioned equidistantly from a reference location.
9. The mobile device accessory of claim 8 , wherein the reference location represents the location of a magnetometer of the mobile computing device in at least one of a vertical or horizontal direction with respect to the mobile device accessory when the mobile device accessory is coupled to the mobile computing device.
10. The mobile device accessory of claim 8 , wherein the reference location is the location of a magnetometer of the mobile computing device when the mobile device accessory is coupled to the mobile computing device.
11. The mobile device accessory of claim 8 , wherein the magnetic field produced by the first electromagnetic coil overlaps with the magnetic field produced by the second electromagnetic coil at the reference location when pressure that exceeds a threshold pressure is applied to each of the first and second pieces of piezoelectric material.
12. The mobile device accessory of claim 5 , wherein:
the first piece of piezoelectric material is positioned within a first wall of the mobile device accessory, the first wall being configured to engage a first edge of the mobile computing device housing; and
the second piece of piezoelectric material is positioned within a second wall of the mobile device accessory, the second wall being configured to engage a second edge of the mobile computing device housing.
13. The mobile device accessory of claim 5 , wherein the first piece of piezoelectric material is electrically isolated from the second piece of piezoelectric material.
14. The mobile device accessory of claim 13 , further comprising an electrically non-conductive material that defines the first inner surface and first outer surface, the first and second pieces of piezoelectric material being positioned within the electrically non-conductive material and being electrically isolated by the electrically non-conductive material.
15. The mobile device accessory of claim 5 , further comprising a diode along an electrical connection between the first piece of piezoelectric material and the first electromagnetic coil.
16. The mobile device accessory of claim 5 , further comprising a capacitor along an electrical connection between the first piece of piezoelectric material and the first electromagnetic coil.
17. The mobile device accessory of claim 5 , further comprising a voltage limiter along an electrical connection between the first piece of piezoelectric material and the first electromagnetic coil.