It involves remote control systems that can distinguish predetermined light sources from stray light sources, e.g., environmental light sources and/or reflections are provided. The predetermined light sources can be disposed in asymmetric substantially linear or two-dimensional patterns. The predetermined light sources also can output waveforms modulated in accordance with one or more signature modulation characteristics. The predetermined light sources also can output light at different signature wavelengths.
Here's Apple's background and summary of the invention: "Some remote control systems use infrared (IR) emitters to determine the position and/or movement of a remote control. For example, if IR emitters are mounted proximate to a television, the remote control may be able to detect its own motion by measuring the motion of the IR emitters with respect to the remote control.
"Such systems, however, often experience a common problem in that they may not be able to distinguish desired or predetermined IR light sources from undesirable environmental IR sources, e.g., the sun or a light bulb. Because those systems may mistake environmental IR sources for IR emitters, they may incorrectly determine the position and/or movement of the remote control.
"Such systems also may experience another common problem in that the systems may not be able to distinguish IR emitters from reflections of the IR emitters, e.g., from the surface of a table or a window. For example, when IR emitters are disposed in a pattern that is symmetrical about a horizontal axis, the remote control system may mistake reflections of the IR emitters from a table surface for the actual IR emitters. Or, when IR emitters are disposed in a pattern that is symmetrical about a vertical axis, the remote control system may mistake reflections of the IR emitters from a window for the actual IR emitters. Again, such mistakes may result in incorrect determinations of the position and/or movement of the remote control.
"The present invention can include remote control systems that can distinguish predetermined light sources from stray or unintended light sources, such as environmental light sources and/or reflections.
"In one embodiment of the present invention, the predetermined light sources can be disposed in asymmetric substantially linear or two-dimensional patterns. Here, a photodetector can detect light output by the predetermined light sources and stray light sources, and transmit data representative of the detected light to one or more controllers. The controllers can identify a derivative pattern of light sources from the detected light indicative of the asymmetric pattern in which the predetermined light sources are disposed.
"In another embodiment of the present invention, the predetermined light sources can output waveforms modulated in accordance with signature modulation characteristics. By identifying light sources that exhibit the signature modulation characteristics, a controller of the present invention can distinguish the predetermined light sources from stray light sources that do not modulate their output in accordance with the signature modulation characteristics.
"In a further embodiment of the present invention, each predetermined light source can output light at one or more different signature wavelengths. For example, a photodetector module of the present invention can detect the signature wavelengths using multiple photodetectors, each of which can detect one of the signature wavelengths. Alternatively, the photodetector module can include an interleaved photodetector having an array of interleaved pixels. Different portions of the interleaved pixels can detect one of the signature wavelengths."
The inventors are Steven Porter Hotelling, Nicolas Vincent King, Robert Duncan Kerry and Wing Dong Low. The graphic below illustrates one embodiment of a remote control system of the present invention having an asymmetric pattern of predetermined light sources.
