US20120154268A1

US20120154268A1 - Remote control systems that can distinguish stray light sources

Info

Publication number: US20120154268A1
Application number: US13/328,644
Authority: US
Inventors: Brett G. Alten
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2007-05-14
Filing date: 2011-12-16
Publication date: 2012-06-21
Also published as: US20080284724A1; US8102365B2

Abstract

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 be configured to exhibit signature characteristics. The predetermined light sources also can output light at different signature wavelengths. The predetermined light sources also can emit light polarized in one or more predetermined polarization axes. Remote control systems of the present invention also can include methods for adjusting an allocation of predetermined light sources and/or the technique used to distinguish the predetermined light sources from the stray light sources.

Description

CROSS-REFERENCE TO RELATED CASES

This application is a divisional of U.S. patent application Ser. No. 11/803,674, filed on May 14, 2007, which is incorporated herein by reference in its entirety. This application is related to U.S. patent application Ser. No. 11/594,313, filed on Nov. 7, 2006, Attorney Docket No. P4736US1, now U.S. Pat. No. 7,566,858, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention can relate to remote control systems that can distinguish one or more predetermined light sources from stray light sources.

BACKGROUND 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 relative motion of the IR emitters with respect to the remote control.
Such systems, however, 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 mistakenly identify unintended environmental IR sources as intended IR emitters, the systems 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.

SUMMARY OF THE INVENTION

The present invention relates to 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 can distinguish the predetermined modulated light sources from those that do not modulate in that same way.
In another 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.
In yet another embodiment of the present invention, a display can have a matrix of pixels having one or more signature pixels. The signature pixel(s) can exhibit one or more signature characteristics that distinguish the signature pixel(s) from the other pixels in the matrix and from other light sources that do not exhibit the signature characteristic(s). For example, the signature pixel(s) can exhibit one or more signature modulation characteristics, wavelengths, polarization axes, intensities, shapes, etc. The present invention also can include methods for adjusting the allocation of signature pixels in the display based on data indicative of conditions under which a photodetector detects the signature pixels.
In another embodiment of the present invention, a light transmitter can be configured to transmit light that is polarized. For example, the light can have one or more predetermined polarization axes. Based on the measured intensity of light received by one or more complementary photodetectors, a controller can distinguish the polarized light from unpolarized stray sources.
The present invention also can include methods for adjusting the technique used for distinguishing predetermined light sources from stray light sources. The adjustment can be based on data indicative of one or more conditions under which a photodetector is detecting light emitted from the predetermined light sources.
Combinations of the embodiments described herein also are within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

FIG. 1 illustrates one embodiment of a remote control system of the present invention having an asymmetric pattern of predetermined light sources;

FIG. 2 illustrates a process for distinguishing predetermined light sources from stray light sources based on the pattern in which the light sources are disposed in accordance with one embodiment of the present invention;

FIGS. 3A-3E illustrate additional embodiments of asymmetric patterns of predetermined light sources in accordance with the present invention;

FIG. 4 illustrates a remote control system of one embodiment of the present invention that can distinguish predetermined light sources from stray light sources based on signature modulation characteristics with which output waveforms of the predetermined light sources are modulated;

FIG. 5 illustrates a process of one embodiment of the present invention for distinguishing predetermined light sources from stray light sources based on signature modulation characteristics with which output waveforms of the predetermined light sources are modulated;

FIGS. 6A-6B illustrate interleaved photodetectors in accordance with one embodiment of the present invention;

FIGS. 7A-B show an illustrative display having one or more integrated signature pixels, the output of which can be used to measure relative controller motion, such as by modulation, polarization, etc., in accordance with one embodiment of the present invention;

FIG. 7C illustrates a process for adjusting the allocation of signature pixels in the display of FIGS. 7A-B based on data indicative of conditions under which a photodetector is detecting light emitted from the signature pixels in accordance with one embodiment of the present invention;

FIG. 8A shows an illustrative remote control system configured to distinguish one or more predetermined light sources from stray light sources by generating and detecting light at one or more predetermined polarization axes in accordance with one embodiment of the present invention;

FIG. 8B shows four illustrative predetermined light sources that emit light in four illustrative predetermined polarization axes in accordance with one embodiment of the present invention;

FIGS. 8C-8F show illustrative relative intensities of light a photodetector can expect to receive from the illustrative predetermined light sources of FIG. 8B when a remote control rolls about the z-axis and the relative locations from which those predetermined light sources can be expected to emit the light in accordance with one embodiment of the present invention; and

FIG. 9 shows an illustrative process for adjusting the technique used by a remote control system for distinguishing predetermined light sources from stray light sources in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention can include remote control systems that can distinguish predetermined light sources from stray light sources, such as environmental light sources and/or reflections.
FIG. 1 illustrates one embodiment of a remote control system of the present invention. Remote control system 10 can include remote control 12 and multiple predetermined light sources 16. Predetermined light sources 16 can be disposed in frame 18 to form light transmitter 14 or integrated with display 20. As used herein, light sources can either generate light or reflect light shined thereon. If light source(s) act as reflector(s), another light source can project light towards the reflector(s). The reflector(s) can reflect the light back to a photodetector. For example, the photodetector and the other light source can be disposed on remote control 12, whereas the reflector(s) can be disposed proximate to, near, on, or in display 20.
Remote control system 10 can permit a user to interact with an image shown on display 20 by manipulating remote control 12. Display 20 can project an image substantially defined by orthogonal x- and y-axes. Display 20 can include a television having a screen with a nominal curvature, a computer monitor having a screen with a nominal curvature, a flat-screen television, a flat-screen monitor, a surface upon which a projector can project images, or any other type of display known in the art or otherwise.
Remote control system 10 can permit a user to move or otherwise select object 19 (e.g., a cursor) shown on display 20 in the x- and y-axes by pointing remote control 12 at desired locations on or proximate to display 20. Ray R can indicate the location at which remote control 12 is pointing. Remote control system 10 can detect the remote control's motion by measuring the motion of predetermined light sources 16 with respect to its own. Based on the detected motion, remote control system 10 can determine the absolute x- and y-positions of the location to which the remote control is pointing with respect to one or more reference locations, e.g., one or more of the predetermined light sources. Remote control system 10 then can be used to move object 19 to the determined location. Thus, when the user moves remote control 12 in the x- and y-axes, display 20 can show a corresponding movement in object 19 in the x- and y-axes.
Predetermined light sources 16 can emit, e.g., infrared (IR) light 22 to remote control 12. Remote control 12 can detect the emitted light using photodetector 24. Photodetector 26 can include CCD arrays, CMOS arrays, two-dimensional position sensitive photodiode arrays, other types of photodiode arrays, other types of light detection devices known in the art or otherwise, or a combination thereof.
In accordance with the present invention, predetermined light sources 16 can be spatially constrained in an asymmetric substantially linear pattern in frame 18. The substantially linear pattern can be parallel to a longitudinal axis of transmitter 14 and asymmetric about an axis orthogonal to the longitudinal axis of transmitter 14. For example, as shown in FIG. 1, remote control system 10 can include three predetermined light sources 16 disposed in a substantially linear pattern. The distance between left-most predetermined light source 16 a and middle predetermined light source 16 b can be less than that between middle predetermined light source 16 b and right-most predetermined light source 16 c. While FIG. 1 illustrates three predetermined light sources, remote control system 10 can include four or more predetermined light sources disposed in an asymmetric substantially linear pattern.
Predetermined light sources 16 can be disposed proximate any edge of display 20, e.g., a top, bottom, or vertical edge of display 20 either in frame 18 or integrated with display 20. Predetermined light sources 16 also can be disposed substantially co-planar with the screen of the display. Alternatively, transmitter 14 and/or predetermined light sources 16 can be disposed at another location near, on, or beneath display 20.
Remote control system 10 also can include controller 26, which can be disposed in remote control 12. Controller 26 can accept data representative of light detected by photodetector 24. In a manner described in greater detail below with respect to FIG. 2, controller 26 can distinguish predetermined light sources from stray light sources using the photodetector data. The controllers described herein can include processors, memory, ASICs, circuits and/or other electronic components.
Remote control 12 also can incorporate user input component 28. A user may actuate user input component 28 when the user wants remote control system 10 to perform an action. For example, a user may actuate user input component 28 when the user is moving remote control 12 and wants object 19 to reflect similar motion on display 20. When the user is not actuating user input component 28, remote control system 10 can be configured to take no action.
User input component 28 can be a scrollwheel similar to that incorporated by a portable media player sold under the trademark iPod™ by Apple Inc. of Cupertino, Calif. The scrollwheel can include one or more buttons and a touchpad or other input device. The touchpad can permit a user to scroll through software menus by running the user's finger around the track of the scrollwheel. User input component 38 also can include, for example, one or more buttons, a touchpad, a touchscreen display, or a combination thereof.
Remote control system 10 also can include optional console 30. Console 30 can have controller 32 that can perform some or all of the processing described for controller 26. For example, remote control 12 can transmit data representing detected IR light 22 to console 30. Controller 32 in console 30 then can identify predetermined light sources 16 from the light sources detected by photodetector 24.
In one embodiment of the present invention, console 30 can communicate with remote control 12 using cable 34 and/or one or more wireless communication protocols known in the art or otherwise. Console 30 also can communicate with transmitter 14 using cable 35 and/or one or more wireless communication protocols known in the art or otherwise. Console 30 also can communicate with display 20 using cable 36 and/or one or more wireless communication protocols known in the art or otherwise. Alternatively, console 30 can be integrated with display 20 as one unit.
Console 30 also can have one or more connectors to which accessories can be coupled. Accessories can include cables, game cartridges, portable memory devices (e.g., memory cards, external hard drives, etc.), adapters for interfacing with another electronic device (e.g., computers, camcorders, cameras, media players, etc.), or combinations thereof.
FIG. 2 illustrates one embodiment of a process that controller 26 or 32 can employ to distinguish predetermined light sources from stray light sources based on the pattern in which the predetermined light sources are disposed. In step 40, controller 26 or 32 can accept data representative of light detected by photodetector 24. In step 42, controller 26 or 32 can identify a plurality of (e.g., all) points of interest (POIs) or detected light sources from the photodetector data, regardless of whether the light source is one of predetermined light sources 16 or a stray light source. Identification of a POI can include determining positional characteristics of the detected light source. As used herein, the “positional characteristics” of a light source or group of light sources can include characteristics that indicate the absolute or relative position and/or geometry of the light source(s), e.g., the absolute x- and y-positions of the light source(s).
To determine the absolute x- and y-positions of the light sources detected by photodetector 24, controller 26 or 32 can use any available techniques known in the art. For example, U.S. Pat. No. 6,184,863 to Sibert et al., issued on Feb. 6, 2001, and No. 7,053,932 to Lin et al, issued on May 30, 2006, the entireties of which are incorporated herein by reference, describe two techniques that can be employed by controller 26 or 32. U.S. Patent Application Publication No. 2004/0207597 to Marks, published on Oct. 21, 2004; No. 2006/0152489 to Sweetser et al., published on Jul. 13, 2006; No. 2006/0152488 to Salsman et al., published on Jul. 13, 2006; and No. 2006/0152487 to Grunnet-Jepsen et al., published on Jul. 13, 2006, the entireties of which also are incorporated herein by reference, describe additional techniques that can be employed by controller 26 or 32. Remote control system 10 also can employ other techniques known in the art or otherwise.
In step 44, controller 26 or 32 can identify a plurality of (e.g., all possible) permutations of the light sources identified in step 42. Each permutation can contain the same number of light sources as the number of predetermined light sources. In the illustrative embodiment of FIG. 1, controller 26 or 32 can identify a plurality of (e.g., all possible) triads, which can be sets of three POIs identified in step 42. In step 46, controller 26 or 32 can correlate the pattern formed by each permutation or triad identified in step 44 to the asymmetric pattern in which predetermined light sources 16 are disposed. Correlation techniques can include statistical techniques, e.g., Chi-square test, least-squares test, or another correlation technique known in the art or otherwise. Controller 26 or 32 can quantify the correlation by determining a correlation coefficient for each permutation or triad. Each correlation coefficient can indicate how well the pattern formed by each permutation matches the pattern formed by the predetermined light sources.
When a user is manipulating remote control 12, the remote control may not be aligned with predetermined light sources 16 in such a way that any of the permutations or triads identified in step 44 will have a pattern that perfectly matches the asymmetric pattern in which predetermined light sources 16 are disposed. Accordingly, in correlating the pattern formed by each permutation or triad identified in step 44 to the asymmetric pattern of predetermined light sources 16, controller 26 or 32 can account for perceived translation, roll, and/or scaling of the asymmetric pattern in the x- and/or y-axes. As used herein, roll of a pattern of predetermined light sources may refer to the rotation of the pattern about an axis orthogonal to the x- and y-axes. Scaling of a pattern of predetermined light sources may refer to the enlargement or reduction of the pattern in the x- and/or y-axes.
In step 48, controller 26 or 32 can identify a predetermined number of N permutations or triads that form patterns that approximate the asymmetric pattern in which predetermined light sources 16 are disposed. Assuming that the correlation coefficients determined in step 46 increase the closer the pattern formed by a permutation correlates to the pattern in which predetermined light sources 16 are disposed, controller 26 or 32 can identify permutations having the best correlation by identifying permutations having the highest correlation coefficients. However, if the correlation coefficients determined in step 46 decrease the closer the pattern formed by a permutation correlates to the pattern in which predetermined light sources 16 are disposed, controller 26 or 32 can identify permutations having the best correlation by identifying permutations having the lowest correlation coefficients.
In step 50, controller 26 or 32 can compare the positional characteristics of each permutation or triad identified in step 48 with “good” values determined in previous solutions. Positional characteristics compared in step 50 may include, e.g., the x-position of each POI, y-position of each POI, perceived translation of the pattern formed by predetermined light sources 16, perceived roll of the pattern formed by predetermined light sources 16, and/or perceived scaling of the pattern formed by predetermined light sources 16. Based on the comparison performed in step 50, controller 26 or 32 can identify the “winning” permutation or triad that most likely corresponds to predetermined light sources 16 in step 52.
In one embodiment of the present invention, controller 26 or 32 can identify in step 48 the permutation having the best correlation (i.e., N=1). In this case, steps 50 and/or 52 may be unnecessary.
As discussed above, remote control 12 may not be aligned with predetermined light sources 16 in such a way that the pattern of the “winning” permutation will perfectly match the asymmetric pattern in which predetermined light sources 16 are disposed. Instead, the pattern of the “winning” permutation may be a derivative indicative of the asymmetric pattern in which predetermined light sources 16 are disposed. For example, the derivative pattern of the “winning” permutation may be translated, rotated, and/or scaled with respect to the asymmetric pattern in which predetermined light sources 16 are disposed.
In one embodiment of the present invention, controller 26 or 32 can continuously reiterate steps 40-52 for each frame of data collected by photodetector 24. However, there may not be a need to distinguish predetermined light sources 16 from stray light sources with each frame of data collected by photodetector 24. In the latter case, controller 26 or 32 can be configured to only perform steps 40-52 for every Jth frame of data collected by photodetector 24, wherein J is a predetermined number. For example, after controller 26 or 32 performs step 44, the controller can be configured to determine whether photodetector 24 has collected J frames of data (step 54). If photodetector 24 has collected J frames of data, controller 26 or 32 then can perform step 46 as described above. However, if photodetector 24 has not collected J frames of data yet, controller 26 or 32 can jump to step 50. That is, controller 26 or 32 can compare positional characteristics of each permutation or triad identified in step 44 with “good” values determined in previous solutions. Based on the comparison performed in step 50, controller 26 or 32 can identify the “winning” permutation that most likely corresponds to predetermined light sources 16 in step 52.
FIGS. 3A-3C illustrate alternative asymmetric patterns in which to dispose predetermined light sources in accordance with the present invention. Similar to the embodiment of FIG. 1, predetermined light sources 62 of FIGS. 3A-3C also can be disposed in frame 64 to form transmitter 60 or integrated with display 20. In the embodiments of FIGS. 3A-3C, however, predetermined light sources 62 can be spatially constrained in a two-dimensional pattern that is asymmetric about longitudinal axis L and/or an axis orthogonal thereto.
For example, as shown in FIG. 3A, predetermined light sources 62 can be disposed in a two-dimensional pattern that is asymmetric about longitudinal axis L. This configuration may be useful to assist remote control system 10 in distinguishing predetermined light sources 62 from reflections of the predetermined light sources from a surface disposed parallel to longitudinal axis L, e.g., a table surface.
As shown in FIG. 3B, predetermined light sources 62 can be disposed in a two-dimensional pattern that is asymmetric about an axis orthogonal to longitudinal axis L. This configuration may be useful to assist remote control system 10 in distinguishing predetermined light sources 62 from reflections of the predetermined light sources from a surface disposed parallel to an axis orthogonal to longitudinal axis L, e.g., a window.
As shown in FIG. 3C, predetermined light sources 62 can be disposed in a two-dimensional pattern that is asymmetric about both longitudinal axis L and an axis orthogonal thereto.
FIGS. 3D-3E illustrate alternative asymmetric patterns in which predetermined light sources can be spatially constrained in accordance with the present invention. Predetermined light sources 72 can be disposed on frames 74 a-74 d, which in turn can be disposed proximate to the edges of display 20, e.g., top, bottom, and/or vertical edges. Alternatively, predetermined light sources 72 can be integrated into display 20 proximate to the edges of display 20. Advantageously, when predetermined light sources are disposed proximate to top and bottom edges of display 20, remote control system 10 can detect a greater range of vertical motion.
When disposed proximate to display, predetermined light sources 72 can form a two-dimensional pattern that can be asymmetric about an axis parallel and/or orthogonal to the direction of gravity. This is not to say that each group of predetermined light sources 72 disposed proximate to each edge of display 20 needs to form a two-dimensional pattern and/or be asymmetric about an axis parallel and/or orthogonal to the direction of gravity. For example, in FIG. 3D, predetermined light sources 72 a can form a symmetric two-dimensional pattern and predetermined light sources 72 b can form an asymmetric one-dimensional pattern. In FIG. 3E, predetermined light sources 72 c and predetermined light sources 72 d each can form an asymmetric substantially linear pattern. Indeed, the pattern formed by predetermined light sources 72 d can be the same pattern formed by predetermined light sources 72 c, but rotated 180 degrees. Advantageously, each of the illustrative patterns formed by the predetermined light sources in FIGS. 3D and 3E may be useful in assisting remote control system 10 to distinguish the predetermined light sources from reflections of the predetermined light sources from surfaces disposed both parallel and orthogonal to the direction of gravity.
Asymmetric arrangements of predetermined light sources, whether in substantially linear or two-dimensional patterns, also can permit remote control system 10 to determine whether remote control 12 is upside-down or not. For example, if a remote control system employs a symmetrical pattern of IR emitters, the controller may not be able to distinguish whether a user is holding the remote control with, e.g., user input component 28 pointing in the positive y-direction or in the negative y-direction. By disposing predetermined light sources 16 in an asymmetric pattern, a controller of the present invention can distinguish between these configurations by comparing the locations of the detected predetermined light sources relative to each other.
In accordance with another aspect of the present invention, remote control systems can modulate output waveform(s) of one or more predetermined light sources in accordance with one or more predetermined or signature modulation characteristics. For example, genres of signature modulation characteristics can include, e.g., frequency, duty cycle, phase shift, another pulse train signature, or a combination thereof. For example, the remote control system can continuously turn two predetermined light sources ON and OFF at first and second predetermined frequencies or otherwise adjust the signal strengths of the two predetermined light source output waveforms at the predetermined frequencies. The first and second frequencies can have the same value or different values. The remote control system can distinguish predetermined light sources that output modulated waveforms from stray light sources by identifying light sources that exhibit the signature modulation characteristics.
FIG. 4 illustrates one embodiment of remote control system 80 of the present invention that can distinguish predetermined light sources from stray light sources by identifying light sources that exhibit, e.g., the signature frequencies at which predetermined light source waveforms may be modulated. Transmitter 81 can include first and second predetermined light sources 82 a and 82 b and one or more frames 84 on which the predetermined light sources are disposed. Modulator(s) 85 can frequency-modulate output of predetermined light sources 82 a and 82 b so that the predetermined light sources are turned ON and OFF at frequencies f1 and f2 (respectively). Alternatively, modulator(s) 85 can frequency-modulate the output of the predetermined light sources so that the signal strengths of the outputs are otherwise adjusted in a predetermined manner at frequencies f1 and f2. In one embodiment of the present invention, light output from predetermined light sources 82 a and 82 b can be modulated at predetermined frequencies that may be less likely to be encountered in a user's environment, e.g., between 100 KHz and 300 KHz, inclusive.
Remote control 86 can include photodetector 88 and controller 90. In one embodiment of the present invention, photodetector 88 can be a two-dimensional position sensitive diode (PSD). In the embodiment of FIG. 4, frequencies f1 and f2 can have different values that are greater than the frame rate at which photodetector 88 captures data.
Controller 90 can include first and second frequency demodulators 92 a and 92 b, each of which can demodulate the photodetector data in accordance with one of the signature frequencies at which predetermined light sources 82 a and 82 b may be modulated. Demodulator 92 a can accept output from photodetector 88 and extract the x- and y-positions of predetermined light source 82 a with respect to remote control 86. Likewise, demodulator 92 b can accept output from photodetector 88 and extract the x- and y-positions of predetermined light source 82 b with respect to remote control 86. In alternative embodiments of the present invention, controller 90 can be disposed in a console, e.g., console 30 of FIG. 1, or within display 20.
While FIG. 4 illustrates transmitter 81 with two predetermined light sources, one of the predetermined light sources can be eliminated or additional predetermined light sources can be added. In the latter case, the predetermined light sources can be disposed in an asymmetric or symmetric pattern. Furthermore, the signature frequency or frequencies at which the predetermined light sources can be modulated can be slower than the frame rate at which a photodetector collects data. In one embodiment of the present invention, one or more predetermined light sources can be modulated at a signature frequency on the order of 10 Hz.
In alternative embodiments of the present invention, modulator(s) 85 can modulate output waveforms of predetermined light sources 82 a and 82 b in accordance with another genre or combinations of genres of signature modulation characteristic(s). Demodulators 92 a and 92 b then can be configured to demodulate output data from photodetector 88 with respect to those genres of signature modulation characteristic(s). In further alternative embodiments of the present invention, the demodulators of FIG. 4 may be replaced with correction filters.
FIG. 5 illustrates one embodiment of a process that a remote control system of the present invention can employ to distinguish predetermined light sources from stray light sources by identifying light sources that exhibit, e.g., the signature frequencies at which output waveforms of the predetermined light sources are modulated. In step 100, the controller can accept data representative of light detected by a photodetector disposed, e.g., in a remote control. In step 102, the controller can identify a plurality of (e.g., all) points of interest (POIs) or detected light sources from the photodetector data, regardless of whether the light source is one of the predetermined light sources or a stray light source. Identification of a POI may include determining positional characteristics of each detected light source.
In step 104, the controller can track each POI identified in step 102 for a predetermined number of M frames. Thereafter, in step 106, the controller can determine a modulation characteristic, e.g., the frequency, at which the light detected for each POI is modulated over those M frames. For stray light sources that may not modulate or infrequently modulates its light output over the M frames, e.g., the sun, the determined frequency may be very low, e.g., approximately zero.
In step 108, the controller can correlate the modulation characteristics, e.g., the frequencies, determined in step 106 to the signature modulation characteristic(s) at which the predetermined light sources are modulated. The controller can quantify the correlation by determining a correlation coefficient for each POI. The correlation coefficient may indicate how well the modulation characteristic determined for each POI in step 106 matches the signature modulation characteristic(s) at which waveforms output by the predetermined light sources are modulated.
In step 110, the controller can identify a predetermined number K of POIs having modulation characteristics that approximate the signature modulation characteristic(s) at which waveforms output by the predetermined light sources are modulated. Assuming that the correlation coefficients determined in step 110 increase the closer a modulation characteristic determined in step 106 correlates to one of the signature modulation characteristics, the controller can identify POIs having the best correlation by identifying the POIs having the highest correlation coefficients. However, if the correlation coefficients determined in step 108 decrease the closer a modulation characteristic determined in step 106 correlates to one of the signature modulation characteristics, the controller can identify POIs having the best correlation by identifying the POIs having the lowest correlation coefficients.
In step 112, the controller can compare the positional characteristics of each POI identified in step 110 with “good” values determined in previous solutions. Based on the comparison performed in step 112, the controller can identify the “winning” POIs that most likely correspond to the predetermined light sources in step 114.
In one embodiment of the present invention, the controller can continuously reiterate steps 100-114 for each frame of data collected by the photodetector. However, there may not be a need to distinguish the predetermined light sources from stray light sources with each frame of data collected by the photodetector. In the latter case, the controller can be configured to only perform steps 100-114 for every Lth frame of data collected by the photodetector, wherein L is a predetermined number. For example, after the controller performs step 102, the controller can be configured to determine whether the photodetector has collected L frames of data (step 116). If the photodetector has collected L frames of data, the controller then can perform step 104 as described above. However, if the photodetector has not collected L frames of data yet, the controller can jump to step 112. That is, the controller can compare the positional characteristics of each POI identified in step 102 with “good” values determined in previous solutions. Based on the comparison performed in step 112, the controller can identify the “winning” POIs that most likely correspond to predetermined light sources in step 114.
In addition to or instead of modulating the outputs of predetermined light sources at signature frequencies, the remote control system of the present invention also can modulate output waveform(s) of one or more predetermined light sources at signature or predetermined duty cycle(s). Output waveforms can be modulated at different or the same predetermined duty cycle(s). The remote control system also can incorporate one or more phase shifts between waveforms output by multiple predetermined light sources.
In one embodiment of the present invention, a remote control system can have two or more predetermined light sources, the output waveforms of which can be modulated in accordance with different signature modulation characteristics having different predetermined values or genres. Advantageously, this may permit the remote control system to determine whether remote control is upside-down. For example, if a remote control system employs a symmetrical pattern of IR emitters, the controller may not be able to distinguish whether a user is holding the remote control with, e.g., a user input component pointing in the positive y-direction or in the negative y-direction. By modulating the predetermined light source outputs in accordance with different signature modulation characteristics, a controller of the present invention can distinguish between these configurations.
In accordance with another aspect of the present invention, predetermined light sources can output light at different signature wavelengths, e.g., in the IR spectrum. For example, a remote control system of the present invention can include first and second predetermined light sources. The first predetermined light source can emit light at first wavelength Al and the second predetermined light source can emit light at second wavelength A2. A photodetector module, e.g., disposed in a remote control, can include first and second photodetectors. The first photodetector can be configured to detect light having first wavelength Al and the second photodetector can be configured to detect light having second wavelength A2. Alternatively, the photodetector module can be an interleaved photodetector. Advantageously, a remote control system having predetermined light sources that output light of different wavelengths can permit the remote control system to determine whether a remote control is upside-down.
FIGS. 6A-6B illustrate embodiments of interleaved photodetectors in accordance with the present invention. Interleaved photodetector 120 can be a single unit having an array of interleaved pixels 122. Predetermined pixels 122 a of the array can be configured to detect light having first wavelength Al whereas other predetermined pixels 122 b of the array can be configured to detect light having second wavelength A2. For example, alternating rows of pixels (see FIG. 6A) or alternating columns of pixels can be configured to detect light having different wavelengths A1 and A2. Alternatively, as shown in FIG. 6B, a checkerboard of pixels can be configured to detect light having different wavelengths Al and A2. In the embodiments of FIGS. 6A-6B, pixels indicated with hatching may be configured to detect light having first wavelength A1 and pixels indicated without hatching may be configured to detect light having second wavelength A2.
FIGS. 7A-B illustrates a display having one or more integrated signature pixels which can be configured to exhibit signature characteristics. Display 130 can incorporate matrix of pixels 132 for showing an image. Pixels 132 can be arranged in any predetermined configuration (e.g., in rows and columns) and driven by a controller, e.g., control circuitry or a processor (not shown). The controller can be disposed in the display itself or in a separate control device (e.g., a computer, set-top box, etc.). To reduce the amount of IR light emitted from the display to the viewer, display 130 also can incorporate IR filter 134, which can cover all or some of pixels 132. IR filter 134 can be applied, for example, onto an internally-facing surface of screen 136.
One or more signature pixels 140 can be integrated into matrix of pixels 132. The signature pixel(s) can exhibit one or more signature characteristics that, when detected by a complementary photodetector, distinguish the signature pixel(s) from light sources that do not exhibit the same signature characteristics. For example, the light emitted by one or more of the signature pixels can be modulated in accordance with one or more signature characteristics, e.g., frequencies, duty cycles, phase shifts, polarization axes, intensities, etc. The light emitted by one or more of the signature pixels also can have a signature wavelength. Each signature pixel or multiple signature pixels also can form one or more signature shapes. For example, a signature pixel can physically have a shape that distinguishes that signature pixel from the other pixels in matrix 132, or multiple signature pixels can form a shape that distinguishes those signature pixels from the other pixels in matrix 132. In one embodiment, the predetermined signature shape can include an asymmetric arrangement of the signature pixels similar to those described herein with respect to FIGS. 1-3E. The signature pixel(s) also can exhibit combinations of these and other signature characteristics.
In one embodiment of the present invention, one or more of signature pixels 140 can occupy a border position of the matrix. One or more of pixels 140 also can occupy an internal position of the matrix. Multiple signature pixels 140 also can be distributed within matrix 132 in an asymmetric pattern similar to those discussed herein with respect to FIGS. 1-3E.
In one embodiment of the present invention, IR filter 134 can have one or more selective transmission features to facilitate communication of IR light emitted by signature pixels 140 through the filter. For example, IR filter can include holes 138 disposed to permit IR light generated by signature pixels 140 to be emitted from display 130 to a photodetector (e.g., in a remote control). This can, for example, permit transmission of signature modulated IR light from signature pixels 140 without undue attenuation in the signal. IR filter 134 also can have one or more high-pass filters, low-pass filters, and/or band-pass filters configured to permit transmission of signature wavelength(s) of light from signature pixels 140. IR filter 134 also can have one or more polarizing filters configured to polarize light emitted from signature pixels 140 in one or more predetermined polarization axes.
To distinguish signature pixel(s) from other sources of light (including the remaining pixels in matrix 132), a remote control similar, for example, to those described with respect to FIGS. 1-6B can be used.
FIG. 7C illustrates a process for adjusting the allocation of signature pixels in the display of FIGS. 7A-B based on data indicative of conditions under which a photodetector is detecting light emitted from the signature pixels in accordance with one embodiment of the present invention. For example, display 130 can be configured to allocate a default number and configuration of pixels from matrix 132 to serve as signature pixels 140. In step 142, a controller in display 130 or another host device can initiate such default allocation of signature pixels. This can include, for example, determining which pixels in matrix 132 will exhibit signature characteristics and, in some cases, generating signals that instruct those signature pixels to exhibit signature characteristics. For example, the default allocation of signature pixels can include a predetermined number of signature pixels chosen to form a predetermined shape and emit light modulated in accordance with predetermined modulation characteristics.
In step 144, the controller can accept data indicative of the conditions under which a complimentary photodetector (e.g., in a remote control) is detecting light emitted from the signature pixels. Such data can include one or more of the following: ambient light data, data indicative of the proximity of the predetermined light sources (e.g., signature pixels) to the photodetector, data indicative of the signal-to-noise ratio, data indicative of the image being shown by the remaining pixels in matrix 132, data from a user indicative of the preferred allocation of signature pixels, etc. One or more sensors can be used to generate some or all of the data accepted in step 144.
In step 146, the controller can identify another subset of signature pixels having a more optimal allocation based on the data gathered in step 144. For example, the controller can determine that more or less pixels of matrix 132 should serve as signature pixels. The controller also can determine that the signature pixels should occupy different locations in matrix 132. For example, if the data indicates that the signal-to-noise ratio is low, the controller may determine that additional pixels from matrix 132 need to serve as signature pixels. Thereafter, in step 148, the controller can generate signals that instruct those additional pixels to exhibit one or more signature characteristics. Alternatively, if the data indicates that the signal-to-noise ratio is high, the controller may determine that one or more of the signature pixels is unnecessary. Thereafter, in step 148, the controller can generate signals for driving those pixels to show an image on the display along with the remaining pixels in matrix 132, rather than exhibit any signature characteristics.
The controller also may determine that a predetermined signature shape formed by the signature pixels in matrix 132 may be inappropriate based on the data collected in step 144. For example, the predetermined shape may be similar to an image shown on display 130 by the remaining pixels in matrix 132 or similar to the shape formed by another light source in the external environment. Responsive to such determination, the controller can identify a set of pixels having a different, more optimal configuration to serve as the signature pixels and, in step 148, generate signals to initiate that more optimal configuration.
The controller can perform steps 144-148 when it is triggered by predetermined events that can occur during operation of a remote control system (e.g., each time the system is turned ON or exits a low-power state). Alternatively, the controller can be configured to perform steps 144-148 at predetermined intervals or continuously during the entire time the remote control system is in operation.
FIG. 8A shows an illustrative remote control system configured to distinguish one or more predetermined light sources from stray light sources by generating and detecting light at one or more predetermined polarization axes in accordance with one embodiment of the present invention. Light transmitter 150 can incorporate, for example, controller 152 and one or more predetermined light sources 154. Controller 152 can generate signals for instructing predetermined light sources 154 to emit light PL at one or more predetermined intensities. To emit polarized light, light source 154 can be a coherent or non-coherent light source (e.g., laser, LED, etc.) and a polarizing filter (not shown) can be used.
Remote 156 can be configured to distinguish predetermined light sources 154 from stray light sources by identifying the light sources that emit light polarized at the predetermined polarization axis or axes. Remote 156 can be equipped, for example, with one or more polarizing filters 158 disposed over photodetector 160. The polarizing filters can have polarization axes that have an orientation or orientations that complement (e.g., match) the polarization axes of the light emitted by light transmitter 150. Polarizing filters 158 can filter out light waves that are not polarized in accordance with its polarization axis or axes. Controller 162 of remote 156 can then analyze the intensities of the detected light to distinguish the predetermined light sources from the stray light sources.
Advantageously, when one or more predetermined light sources are configured to emit light at one or more predetermined polarization axes and one or more predetermined intensities, controller 162 can determine the roll of remote control 156 based on the intensity of the light received from the predetermined light sources. For example, if the predetermined polarization axis aligns with the Y axis, photodetector 160 may detect decreasing intensity from light emitted by predetermined light source 154 as remote 156 (and thus the orientation of polarizing filter 158) is rotated out of alignment with the Y-axis towards the X-axis. The amount of roll can be calculated as a function of the intensity.
In one embodiment of the present invention, light source 154 can include two or more predetermined light sources configured to emit light at one or more predetermined polarization axes and at one or more predetermined intensities. Because the relative polarizations, intensities, and locations of the predetermined light sources are known, controller 162 can distinguish the predetermined light sources from stray light sources by identifying the light sources having the expected relative intensities.
Although FIG. 8A illustrates light transmitter 150 as being an independent device, light transmitter 150 can be integrated within a host electronic device, e.g., a display. If the light transmitter is integrated within a host device, controller 152 can be dedicated to controlling light source 154 or combined with another controller in the host device.
Furthermore, although FIG. 8A illustrates photodetector 160 and polarizing filter 158 disposed in remote 156, in an alternative embodiment of the present invention, light transmitter 150 can instead be integrated within remote 156 and photodetector 160 and polarizing filter 158 can be integrated into a host device or be provided as an independent unit.
FIG. 8B shows four illustrative predetermined light sources that emit light in four illustrative predetermined polarization axes in accordance with one embodiment of the present invention. In the illustrative embodiment shown in FIG. 8B, four predetermined light sources A-D can emit light having polarization axes orientated along the x-axis, at 45° angle with respect to the x- and y-axes, at 135° angle with respect to the x- and y-axes, and along the y-axis, respectively. The predetermined light sources can be disposed, for example, in a structurally-independent light transmitter, in a display, in remote control 156, or in another host device. Complementary photodetector 160 and polarizing filter 158 can be disposed, for example, in remote control 156 or another host device. Polarizing filter 158 can have a polarization axis illustratively oriented along the x-axis either permanently (e.g., when the filter is disposed in a immobile host device) or (if incorporated within remote control 156) when the remote control is disposed with user input component 164 pointing in the positive y-direction.
FIGS. 8C-8F show illustrative relative intensities of light photodetector 160 can expect to receive from illustrative predetermined light sources A-D of FIG. 8B when remote control 156 rolls about the z-axis and the relative locations from which those predetermined light sources can be expected to emit the light in accordance with one embodiment of the present invention. For example, when remote control 156 is disposed with user input component 164 pointing in the positive y-axis (FIG. 8C), photodetector 160 can expect to detect a datum level of 100% light intensity from predetermined light source A after the incoming light is filtered by polarizing filter 158. In comparison to that datum level and assuming that all predetermined light sources A-D emit substantially the same intensity of light, photodetector 160 can expect to detect 50% light intensity from predetermined light sources B and C and 0% light intensity from predetermined light source D, after the incoming light is filtered by polarizing filter 158. When remote control 156 is disposed with user input component 164 pointing in the negative x-axis (FIG. 8D), photodetector 160 can expect to detect a datum level of 100% light intensity from predetermined light source D, 50% light intensity from predetermined light sources B and C, and 0% light intensity from predetermined light source A.
When remote control 156 is disposed with user input component 164 pointing in the negative y-axis (FIG. 8E) or in the positive x-axis (FIG. 8F), photodetector 160 can expect to detect the same relative intensities of light from predetermined light sources A-D as compared to those when the remote control 156 is disposed with the user input component pointed in the positive y-axis and negative x-axis, respectively. However, the oppositely corresponding orientations of remote control 156 can be distinguished from each other based on the relative locations from which those predetermined light sources can be expected to emit light. For example, in FIG. 8C, photodetector 160 can expect to receive light emitted by predetermined light source A from the top left corner of the group of predetermined light sources. In comparison, photodetector 160 can expect to receive light emitted by predetermined light source A from the bottom right corner of the group of predetermined light sources in FIG. 8E. Similarly, in FIGS. 8D and 8F, photodetector 160 can expect to receive light emitted by predetermined light source D from the bottom left corner and the top right corner of the group of predetermined light sources, respectively.
The oppositely corresponding orientations of remote control 156 also can be distinguished, for example, by (1) comparing data from the current data frame to data from one or more preceding frames; (2) disposing the predetermined light sources in an asymmetric pattern similar to those discussed with respect to FIGS. 1-3E; (3) configuring one or more of the predetermined light sources to exhibit a different signature characteristic; (4) accepting data from a single or multi-dimensional accelerometer or other sensor that can generate data indicative of the orientation of the remote control; or (5) any combination thereof.
While FIGS. 8B-8F illustrate four predetermined light sources, a remote control system of the present invention can include more than four predetermined light sources that emit light in one or more predetermined polarization axes. Alternatively, one or more of the predetermined light sources can be eliminated. For example, two or three predetermined light sources can be configured to emit light in one or more predetermined polarization axes. Because the expected relative intensities of light and the relative locations from which the predetermined light sources can be expected to emit the light are known, the remote control system of the present invention can distinguish the predetermined light sources from stray light sources.
In an alternative embodiment of the present invention, remote 156 can simultaneously transmit and receive light from a separate light transmitter in accordance with the principles of the present invention. For example, remote 156 can transmit polarized light to a first set of photodetector and polarizing filter that are integrated into a host device or provided in an independent unit. Remote 156 also can incorporate its own photodetector and polarizing filter to receive polarized light from a separate light transmitter disposed, for example, in the same device that houses the first set of photodetector and polarizing filter.
In accordance with another aspect of the present invention, a remote control system of the present invention can combine two or more of the embodiments described herein. For example, a remote control system of the present invention can have multiple predetermined light sources disposed in an asymmetric pattern. The output waveform of one of the predetermined light sources can be modulated in accordance with one or more signature modulation characteristics. The remote control system of the present invention can be configured to distinguish the predetermined light sources from stray light sources using a two step process. First, the remote control system can identify a light source that exhibits the signature modulation characteristic(s). Second, the remote control system can identify a derivative pattern of light sources that include the light source identified in the first step and that is indicative of the asymmetric pattern in which the predetermined light sources are disposed.
FIG. 9 shows an illustrative process for adjusting the technique used for distinguishing predetermined light sources from stray light sources in accordance with one embodiment of the present invention. In one embodiment, a remote control system can be equipped with the hardware and software to support multiple techniques for distinguishing predetermined light sources from stray light sources (e.g., any of the techniques described herein). Based on data indicative of conditions under which the system is detecting the predetermined light sources, the system can be configured to adjust the technique used.
In step 170, a controller in a light transmitter, remote control, console, display, and/or other host unit can identify a default technique for distinguishing predetermined light sources from stray light sources. The default technique may include any one or more of the embodiments described herein with respect to FIGS. 1-8F. In step 172, the controller can initiate the default technique. This can include, for example, identifying pixels in an asymmetric pattern in a display to serve as signature pixels and/or identifying other predetermined light sources to be driven to exhibit one or more signature characteristics. This also can include generating signals that instruct those pixels and/or predetermined light sources to emit light in accordance with the default technique.
In step 174, the controller can accept data indicative of one or more conditions under which the remote control is detecting light emitted from the predetermined light sources. Again, such data can include one or more of the following: ambient light data, data indicative of the proximity of the predetermined light sources to the photodetector, data indicative of the signal-to-noise ratio, data indicative of the image being shown by a display associated with the predetermined light sources or remote control system, data from a user indicative of a user-preferred technique, etc. One or more sensors can be used to generate some or all of the data accepted in step 174.
In step 176, the controller can identify another technique for distinguishing predetermined light sources from other light sources based on the data gathered in step 174. For example, if the default technique results in a low signal-to-noise ratio, the controller may change the technique employed for distinguishing the predetermined light sources to attempt to increase the signal-to-noise ratio.
In one embodiment of the present invention, each technique for distinguishing predetermined light sources that is supported by the remote control system can be associated with one or more conditions under which the technique is more suited. For example, one or more techniques may be better suited for use during the daytime whereas other techniques may be better suited for use during the evenings. Thus, in step 176, the controller may change the technique employed for distinguishing the predetermined light sources based on ambient light data. Alternatively, one or more techniques may be better suited than other techniques when the predetermined light sources are located far away from the photodetector. Thus, in step 176, the controller may change the technique employed for distinguishing the predetermined light sources based on data indicative of the proximity of the predetermined light sources to the photodetector.
Thereafter, in step 178, the controller can initiate the other technique selected in step 176 by, for example, generating drive signals for the appropriate hardware.
The controller can perform steps 170-178 when it is triggered by predetermined event that can occur during operation of a remote control system (e.g., each time the system is turned ON or exits a low-power state). Alternatively, the controller can be configured to perform steps 170-178 at predetermined intervals or continuously during the entire time the remote control system is in operation.
Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration. Alternative embodiments of those described hereinabove also are within the scope of the present invention. For example, predetermined light sources can be disposed in a remote control and a photodetector can be disposed in a display, in a frame disposed proximate to the display, or at any location proximate to, on, or near a display.
A remote control of the present invention can be any electronic device in a system that may need to distinguish predetermined light sources from stray light sources. For example, the remote control can be any portable, mobile, hand-held, or miniature consumer electronic device. Illustrative electronic devices can include, but are not limited to, music players, video players, still image players, game players, other media players, music recorders, video recorders, cameras, other media recorders, radios, medical equipment, calculators, cellular phones, other wireless communication devices, personal digital assistances, programmable remote controls, pagers, laptop computers, printers, or combinations thereof. Miniature electronic devices may have a form factor that is smaller than that of hand-held devices. Illustrative miniature electronic devices can include, but are not limited to, watches, rings, necklaces, belts, accessories for belts, headsets, accessories for shoes, virtual reality devices, other wearable electronics, accessories for sporting equipment, accessories for fitness equipment, key chains, or combinations thereof.
While the above description may have described certain components as being physically separate from other components, one or more of the components can be integrated into one unit. For example, the photodetector or photodetector module can be integrated with one or more controllers.
Also, a controller in the display can perform some or all of the processing described above for controllers 26 and/or 32. Thus, multiple controllers may be used to control remote control systems of the present invention.
Furthermore, while the illustrative remote control systems described above may have included predetermined light sources that output light waves, one or more of the predetermined light sources can be replaced with component(s) that output or reflect other types of energy waves either alone or in conjunction with light waves. For example, the component(s) can output radio waves.
The above described embodiments of the present invention are presented for purposes of illustration and not of limitation, and the present invention is limited only by the claims which follow.

Claims

1.-20. (canceled)

21. A system comprising:

one or more predetermined light sources configured to emit light polarized in one or more predetermined polarization axes;

a photodetector for detecting light from light sources, wherein the photodetector is configured to generate photodetector data;

one or more polarizing filters disposed to accept light from the light sources before the light is detected by the photodetector, wherein the one or more polarizing filters are configured in one or more predetermined polarization axes; and

a controller configured to distinguish the one or more predetermined light sources from other light sources based on the photodetector data.

22. The system of claim 21, wherein the one or more predetermined light sources comprise multiple predetermined light sources disposed in a pattern that is asymmetric about at least a first axis.

23. The system of claim 22, wherein the controller is configured to identify multiple light sources from the photodetector data that form a derivative pattern indicative of the asymmetric pattern.

24. The system of claim 21, wherein:

the one or more predetermined light sources comprise multiple predetermined light sources; and

the controller is configured to identify multiple light sources from the photodetector data that exhibit expected relative intensities.

25. The system of claim 21, wherein the photodetector, one or more polarizing filters, and controller are disposed in a remote control.

26. The system of claim 21, wherein the one or more predetermined light sources are disposed in a remote control.

27. A method for distinguishing multiple predetermined light sources from stray light sources, the method comprising:

emitting polarized light from the multiple predetermined light sources at one or more predetermined intensities, wherein the polarized light is polarized in one or more predetermined polarization axes;

filtering light from light sources using one or more polarizing filters;

detecting light from the light sources using a photodetector after the light is filtered by the polarizing filter;

generating photodetector data representative of the detected light; and

identifying multiple light sources from the photodetector data that exhibit expected relative intensities.

28. The method of claim 27, wherein the multiple predetermined light sources is disposed in a pattern that is asymmetric about at least a first axis, the method further comprising identifying multiple light sources from the photodetector data that form a derivative pattern indicative of the asymmetric pattern.

29. The method of claim 27, wherein the photodetector and polarizing filter are disposed in a remote control, the method further comprising generating signals responsive to user actuation of a user input component of the remote control.

30. The method of claim 27, wherein the one or more predetermined light sources are disposed in a remote control, the method further comprising generating signals responsive to user actuation of a user input component of the remote control.

31. The method of claim 27, wherein emitting polarized light from the multiple predetermined light sources comprises emitting polarized light from multiple coherent light sources.

32. The method of claim 27, wherein emitting polarized light from the multiple predetermined light sources comprises emitting polarized light through one or more polarizing filters.

33. A method for identifying a technique for distinguishing one or more predetermined light sources from other light sources, the method comprising:

accepting data indicative of one or more conditions under which a photodetector is detecting light emitted from the one or more predetermined light sources; and

identifying a first technique for distinguishing the one or more predetermined light sources from the other light sources based on the data.

34. The method of claim 33, further comprising initiating the first technique by generating signals for controlling hardware associated with the first technique.

35. The method of claim 33, further comprising:

identifying a second technique for distinguishing the one or more predetermined light sources from the other light sources, wherein the second technique comprises a default technique; and

changing from the second technique to the first technique to distinguish the one or more predetermined light sources from the other light sources.

36. The method of claim 33, wherein the data comprises ambient light data, data indicative of the proximity of the one or more predetermined light sources to the photodetector, data indicative of an image being shown by a display associated with the one or more predetermined light sources, data indicative of a signal-to-noise ratio, data from a user indicative of a user-preferred technique, or any combination thereof.