PATENT DOCUMENT

Publication Number: US-7655937-B2
Application Number: US-17454208-A
Country: US
Kind Code: B2

Title: Remote control systems that can distinguish stray light sources

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 output waveforms modulated in accordance with one or more signature modulation characteristics. The predetermined light sources also can output light at different signature wavelengths.

Claims:
1. A method for distinguishing at least one predetermined light source from stray light sources, the method comprising:
 continuously modulating an output waveform of the at least one predetermined light source in accordance with at least one signature modulation characteristic; 
 detecting light from light sources using a photodetector; 
 generating photodetector data representative of the detected light; and 
 identifying at least one light source from the photodetector data that exhibits the at least one signature modulation characteristic. 
 
   
   
     2. The method of  claim 1 , wherein modulating an output waveform of the at least one predetermined light source comprises turning the at least one predetermined light source ON and OFF in accordance with the at least one signature modulation characteristic. 
   
   
     3. The method of  claim 1 , wherein modulating an output waveform of the at least one predetermined light source comprises adjusting signal strength of the output waveform in a predetermined manner in accordance with the at least one signature modulation characteristic. 
   
   
     4. The method of  claim 1 , wherein:
 the at least one predetermined light source comprises at least first and second predetermined light sources; 
 modulating an output waveform of the at least one predetermined light source comprises modulating an output waveform of the first predetermined light source in accordance with at least a first signature modulation characteristic, and modulating an output waveform of the second predetermined light source in accordance with at least a second signature modulation characteristic; and 
 identifying at least one light source comprises identifying a first light source that exhibits the first signature modulation characteristic, and identifying a second light source that exhibits the second signature modulation characteristic. 
 
   
   
     5. The method of  claim 1 , wherein the at least one signature modulation characteristic comprises a predetermined frequency at which the output waveform of the at least one predetermined light source is modulated, a predetermined duty cycle at which the output waveform of the at least one predetermined light source is modulated, a phase shift, or a combination thereof. 
   
   
     6. The method of  claim 1 , wherein identifying at least one light source comprises demodulating the photodetector data in accordance with the at least one signature modulation characteristic. 
   
   
     7. The method of  claim 1 , wherein:
 the photodetector comprises a two-dimensional position sensitive diode; and 
 detecting light from light sources comprises detecting light from light sources using the two-dimensional position sensitive diode. 
 
   
   
     8. The method of  claim 1 , further comprising determining the position of the photodetector with respect to the identified at least one light source. 
   
   
     9. The method of  claim 1 , wherein:
 the at least one predetermined light sources comprises a plurality of predetermined light sources; 
 the plurality of predetermined light sources are disposed in a target pattern; and 
 the identifying at least one light source is based on the target pattern. 
 
   
   
     10. A system comprising:
 a first predetermined light source configured to emit light at a first signature wavelength; 
 a second predetermined light source configured to emit light at a second signature wavelength, wherein the first signature wavelength is different than the second signature wavelength; and 
 a remote control having a photodetector module, wherein the photodetector module is configured to detect the first and second signature wavelengths of light. 
 
   
   
     11. The system of  claim 10 , wherein the photodetector module comprises first and second photodetectors, wherein the first photodetector is configured to detect the first wavelength of light and the second photodetector is configured to detect the second wavelength of light. 
   
   
     12. The system of  claim 10 , wherein the photodetector module comprises an array of interleaved pixels, wherein a first portion of the interleaved pixels are configured to detect the first wavelength of light and a second portion of the interleaved pixels is configured to detect the second wavelength of light. 
   
   
     13. The system of  claim 12 , wherein the first and second portions form alternating rows of the array. 
   
   
     14. The system of  claim 12 , wherein the first and second portions form alternating columns of the array. 
   
   
     15. The system of  claim 12 , wherein the first and second portions form a checkerboard pattern. 
   
   
     16. The system of  claim 10 , wherein the first and second predetermined light sources are disposed in a display. 
   
   
     17. The system of  claim 10 , further comprising a remote control within which the photodetector module is disposed. 
   
   
     18. The system of  claim 10 , further comprising circuitry configured to determine whether the remote control is upside-down. 
   
   
     19. The system of  claim 10 , further comprising circuitry configured to determine the position of the remote control with respect to the first and second predetermined light sources.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This is a divisional of U.S. application Ser. No. 11/594,313, filed Nov. 7, 2006, which is incorporated by reference herein in its entirety. 

   FIELD OF THE INVENTION 
   The present invention can relate to remote control systems that can distinguish 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 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. 
   SUMMARY OF THE INVENTION 
   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. 

   
     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; and 
       FIGS. 6A-6B  illustrate interleaved photodetectors 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)  10  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&#39;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 my 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 Computer, 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&#39;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  40  also can have one or more connectors  43  to which accessories can be coupled. Accessories can include cables  44  and/or  46 , 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 U.S. Pat. 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 f 1  and f 2  (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 f 1  and f 2 . 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&#39;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 f 1  and f 2  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 λ 1  and the second predetermined light source can emit light at second wavelength λ 2 . 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 λ 1  and the second photodetector can be configured to detect light having second wavelength λ 2 . 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 λ 1  whereas other predetermined pixels  122   b  of the array can be configured to detect light having second wavelength λ 2 . For example, alternating rows of pixels (see  FIG. 6A ) or alternating columns of pixels can be configured to detect light having different wavelengths λ 1  and λ 2 . Alternatively, as shown in  FIG. 6B , a checkerboard of pixels can be configured to detect light having different wavelengths λ 1  and λ 2 . In the embodiments of  FIGS. 6A-6B , pixels indicated with hatching may be configured to detect light having first wavelength λ 1  and pixels indicated without hatching may be configured to detect light having second wavelength λ 2 . 
   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 above. 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. 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. 
   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.

Metadata:
Filing Date: 20080716
Publication Date: 20100202
Grant Date: 20100202
Priority Date: 20061107
Inventors: HOTELLING STEVEN PORTER
KING NICHOLAS VINCENT
KERR DUNCAN ROBERT
LOW WING KONG
Assignee: APPLE INC
CPC Classifications: [{"code": "G08C23/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04N21/42221", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N21/42204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/44", "inventive": true, "first": true, "tree": "[]"}, {"code": "G08C2201/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04N21/42204", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "G08C23/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01J1/4204", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N21/42221", "inventive": true, "first": false, "tree": "[]"}, {"code": "G08C2201/32", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 39462655