Optical navigation module with decoration light using interference avoidance method
A method of eliminating interference at an optical sensor of a mobile device that receives light from multiple light sources. The mobile device includes an optical navigation module having a cover and an illumination device disposed around the periphery of the cover. The optical navigation module includes an optical sensor that detects light reflected from an object contacting the cover. A processor receives electrical signals from the optical sensor and interprets movement of the object. The method reduces interference between the light source of the optical navigation module and the light source of the illumination device by controlling emission of light rays from each light source. The emission of light rays may be controlled based on timing, frequency and/or coding domains.
1. A handheld communication device comprising:
an optical navigation module comprising:
a cover having a top surface and a bottom surface;
a navigation light source that illuminates the cover;
a decorative light source that illuminates a periphery of the cover; and
an optical sensor that detects light reflected from an external object that contacts the top surface of the cover, the optical sensor generating corresponding contact signals; and
a processor electrically coupled to the navigation light source, the decorative light source and the optical sensor, the processor operable to:
activate the navigation light source while concurrently deactivating the decorative light source;
activate the decorative light source while concurrently deactivating the navigation light source; and
produces a digitally encoded first signal to control the navigation light source and a digitally encoded second signal to control the decorative light source, the digitally encoded first and second signals comprising a series of on-pulses and off-pulses.
2. The handheld communication device of claim 1 , wherein the optical navigation module further comprises an illumination ring that is optically coupled to the decorative light source, the illumination ring disposed around the periphery of the cover.
3. The handheld communication device of claim 1 , wherein the processor controls operation of the navigation light source and the decorative light source so that the digitally encoded first signal comprises an on-pulse when the digitally encoded second signal comprises and off-pulse and the digitally encoded first signal comprises an off-pulse when the digitally encoded second signal comprises an on-pulse.
4. The handheld communication device of claim 1 , wherein the digitally encoded first and second signals are pulse width modulation signals.
5. The handheld communication device of claim 4 , wherein the digitally encoded first signal has a first duty cycle and the digitally encoded second signal has a second duty cycle.
6. The handheld communication device of claim 5 , wherein the digitally encoded first signal has a duty cycle of substantially 30% and the digitally encoded second signal has a duty cycle of substantially 70%.
7. The handheld communication device of claim 2 , wherein the digitally encoded first signal and the digitally encoded second signal are configured such that the illumination ring is perceivable to be operating at a same time that the navigation pad is operating.
8. The handheld communication device of claim 1 , wherein the digitally encoded first and second signals operate at substantially 30 MHz.
9. The handheld communication device of claim 1 , wherein the optical sensor is positioned below the bottom surface of the cover.
10. The handheld communication device of claim 1 , wherein the processor is programmed to detect movement of an object along one or both of an X axis and a Y axis when the object is in contact with the top surface of the cover.