PATENT DOCUMENT

Publication Number: US-7599044-B2
Application Number: US-16595805-A
Country: US
Kind Code: B2

Title: Method and apparatus for remotely detecting presence

Abstract:
An apparatus for detecting a person&#39;s presence without requiring the person to provide auditory or tactile input. The invention may be incorporated into an electronic device, such as a desktop computer or notebook computer. The embodiment may employ a variety of radiation emissions to determine when a person enters the embodiment&#39;s field of detection and, in response to the person entering, activate the electronic device. This may prove particularly useful where, for example, the electronic device consumes significant power and/or may suffer deleterious effects if left active for too long.

Claims:
1. A method for detecting a presence, comprising:
 receiving a beam having an angle of reflection; 
 in the event the angle of reflection exceeds a minimum angle, electronically determining that an object reflecting the beam is within a detection field; and 
 in the event the object is within the detection field, activating a related device. 
 
     
     
       2. The method of  claim 1 , further comprising emitting the beam at an exit angle from an emitter. 
     
     
       3. The method of  claim 2 , further comprising receiving the beam at an entry angle at a detector. 
     
     
       4. The method of  claim 3 , further comprising determining the angle of reflection from the exit and angle the entry angle. 
     
     
       5. The method of  claim 4 , wherein the operation of determining the angle of reflection comprises:
 adding the exit angle to the entry angle to yield a sum; and 
 equating the angle of reflection to the sum. 
 
     
     
       6. The method of  claim 1 , further comprising:
 determining if the object is in motion; and 
 only in the event the object is in motion, activating the related device. 
 
     
     
       7. The method of  claim 6 , wherein the operation of determining if the object is in motion comprises:
 subjecting the beam to a filter to produce a filtered signal; 
 from a signal value of the beam and a signal value of the filtered signal, determining if the beam undergoes a change for at least a minimum time; and 
 in the event the beam undergoes the change for at least the minimum time, determining the object is in motion. 
 
     
     
       8. The method of  claim 6 , wherein the operation of activating the related device comprises waking the related device. 
     
     
       9. The method of  claim 8 , wherein the related device is a computer. 
     
     
       10. The method of  claim 1 , wherein the detection field is a less than the maximum detectable area. 
     
     
       11. An apparatus for detecting a presence, comprising:
 an emitter operative to project a beam; 
 a detector operative to receive the beam; and 
 a logic operative to determine whether the beam is reflected from an object within a detection field associated with the emitter by determining if an angle of reflection of the beam exceeds a minimum angle. 
 
     
     
       12. The apparatus of  claim 11 , wherein the emitter emits an infrared beam. 
     
     
       13. The apparatus of  claim 11 , wherein the emitter emits visible light. 
     
     
       14. The apparatus of  claim 11 , wherein the emitter emits ultraviolet light. 
     
     
       15. The apparatus of  claim 11 , wherein the emitter emits a steered laser. 
     
     
       16. The apparatus of  claim 11 , wherein the emitter comprises at least one light-emitting diode. 
     
     
       17. The apparatus of  claim 16 , wherein the detector comprises at least one sensor operable to detect the beam emitted by the light-emitting diode. 
     
     
       18. The apparatus of  claim 11 , wherein:
 the emitter comprises a plurality of light-emitting diodes arranged in an emitter pattern; 
 the detector comprises a plurality of sensors arranged in a detector pattern complementary to the pattern of the emitter; and 
 the detector is operative to scan at least a first sensor upon actuation of one of the plurality of light-emitting diodes. 
 
     
     
       19. The apparatus of  claim 18 , wherein:
 the emitter pattern is a two-dimensional array; 
 the detector pattern is a two-dimensional array; 
 the emitter is operative to actuate each of the light-emitting diodes in the two-dimensional array sequentially; and 
 the detector is operative to scan each of the sensors having at least one common coordinate with each of the light-emitting diodes as each of the light-emitting diodes is actuated. 
 
     
     
       20. The apparatus of  claim 19 , wherein the logic is operative to determine whether the beam is reflected from an object within a detection field associated with the emitter by determining an angle of reflection for the beam, and employing the angle of reflection to triangulate a location of the object. 
     
     
       21. The apparatus of  claim 20 , wherein:
 the logic is further operative to measure a duration of a change associated with the beam; and 
 the logic is operative to activate the related device in the event the duration of the change exceeds a threshold value. 
 
     
     
       22. The apparatus of  claim 11 , wherein:
 the detector is further operative to detect a level of ambient light; and 
 the detector is further operative to adjust a parameter of the related device to accommodate the level of ambient light. 
 
     
     
       23. The apparatus of  claim 11 , wherein the detector is further operative to act as a videoconferencing camera. 
     
     
       24. A computer operative to detect a presence, comprising:
 an emitter comprising at least one light-emitting diode, the light-emitting diode operative to project a beam at an exit angle; 
 a detector comprising at least one sensor, the sensor operative to receive the beam at an entry angle after the beam reflects off an object; 
 a logic operative to determine an angle of reflection based on the exit angle and entry angle, the logic further operative to determine if the object is in motion, the logic further operative to determine the object is present if the object is in motion and if the object is within a detection field based on the angle of reflection exceeding a minimum angle. 
 
     
     
       25. The computer of  claim 24 , wherein the parameter of the computer system is a power state. 
     
     
       26. The computer of  claim 24 , wherein the computer is a notebook computer. 
     
     
       27. The computer of  claim 24 , wherein the computer is a desktop computer. 
     
     
       28. A method for detecting a presence, comprising:
 receiving a beam having an angle of reflection; 
 comparing the angle of reflection to a minimum angle of reflection; 
 in the event the angle of reflection at least one of equals or exceeds the minimum angle of reflection, determining the object is within the detection field; and 
 in the event the object is within the detection field, activating a related device. 
 
     
     
       29. The method of  claim 28 , wherein the minimum angle of reflection equals an arctangent of the detection field&#39;s width divided by the detection field&#39;s depth. 
     
     
       30. A method for detecting a presence, comprising:
 receiving a beam having an angle of reflection; 
 in the event the angle of reflection is less than a minimum angle, electronically determining that an object reflecting the beam is not within a detection field; and
 in the event the object is within the detection field, activating a related device.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to presence detection, and more specifically to a method and apparatus for remotely detecting a person&#39;s presence without requiring physical input by the person. 
     2. Background Art 
     Computing systems have grown in complexity, and thus in power consumption. Indeed, many electronic devices are remarkably more sophisticated than their counterparts from a decade ago, or even several years ago. As devices offer additional functionality, users have come to expect even more enhancements. 
     Generally speaking, such enhancements come at a price. First, power requirements for electronics may increase with complexity and function. Second, the increasing sophistication of consumer electronics may cause many potential purchasers to avoid too-complex products, fearing such products will prove difficult to use. Third, with increase in complexity and sophistication of electronic products comes an increased premium in the space available to incorporate additional features and designs. Space within a product may be extremely limited, and thus valuable. 
     Further, many electronic products operate on battery power. Enhancing the battery life may prove useful and desirable to consumers, as the product will more likely be available when the consumer desires its use. Thus, there is a need in the art for a method for improving battery life of an electronic product. 
     Improved operating experiences with electronic products may minimize a consumer&#39;s fear of a product&#39;s complexity. Enhanced user interfaces are one example of how to improve an operating experience. Yet another is personalization of a product, as is implementing a manner for a product to recognize a user&#39;s presence. Accordingly, there is a need in the art for recognizing a user&#39;s presence and accustoming the user to the activation of the product. 
     Additionally, the function of aesthetics in a purchaser&#39;s decision to choose one product over another should not be underestimated. Many consumers, when faced with two virtually identical products, will choose the “prettier” or better-looking product. Many consumers find smooth, uniform surfaces particularly attractive, especially in electronic products. With the proliferation of remote controls, windows or ports must be placed in products to receive a signal from the remote control. Similarly, many products (such as televisions, computer monitors, and even some remote controls) automatically adjust their brightness to account for a level of ambient light. Light sensors are required for such activities, and in turn require yet another port or opening in the surface of the electronic product. The inclusion of too many of these ports may detract from the overall look of the product, thus swaying a potential purchaser to buy a different, competing product. Accordingly, there is a need in the art for an apparatus that may combine the functions of several sensors in a single element. 
     That the present invention satisfies these needs will be apparent to one of ordinary skill in the art upon reading this disclosure. 
     BRIEF SUMMARY OF THE INVENTION 
     Generally, one embodiment of the present invention takes the form of an apparatus for detecting a person&#39;s presence without requiring the person to provide auditory or tactile input. For example, an embodiment of the present invention may be incorporated into an electronic device, such as a desktop computer or notebook computer. The embodiment may employ a variety of radiation emissions to determine when a person enters the embodiment&#39;s field of detection and, in response to the person entering, activate the electronic device. This may prove particularly useful where, for example, the electronic device consumes significant power and/or may suffer deleterious effects if left active for too long. When used in a notebook or desktop computer, for example, the embodiment may minimize power consumption by permitting the notebook to sleep and yet provide convenience for a user by automatically waking the notebook as the user approaches. Not only does this eliminate any requirement for the user to tap a key, press a mouse button, or otherwise interact with the computer, but it may provide an enhanced user experience upon approaching the computer. 
     Another embodiment of the present invention includes a method for detecting a presence, comprising receiving a beam having an angle of reflection; determining from the angle of reflection if an object reflecting the beam is within a detection field; and in the event the object is within the detection field, activating a related device. The method may further include emitting the beam at an exit angle from an emitter, and/or receiving the beam at an entry angle at a detector. Additionally, the method may determine the angle of reflection from the exit angle and the entry angle. The method may determine the angle of reflection by adding the exit angle to the entry angle to yield a sum, and equating the angle of reflection to the sum. Further, the method may compare the angle of reflection to a minimum angle of reflection, and, in the event the angle of reflection at least one of equals or exceeds the minimum angle of reflection, determine the object is within the detection field. 
     Another embodiment of the present invention may take the form of an apparatus for detecting a presence, comprising an emitter operative to project a beam, a detector operative to receive the beam, and a logic operative to determine whether the beam is reflected from an object within a detection field associated with the emitter. In such an embodiment, the emitter may include a plurality of light-emitting diodes arranged in an emitter pattern, the detector may include a plurality of sensors arranged in a detector pattern complementary to the pattern of the emitter, and the detector may be operative to scan at least a first sensor upon actuation of one of the plurality of light-emitting diodes. 
     Additional features and advantages of the present invention will become apparent to those of ordinary skill in the art upon reading the entirety of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  depicts a first embodiment of the present invention in operation. 
         FIG. 2  depicts a top-down view of the embodiment of  FIG. 1 . 
         FIG. 3  depicts a top-down view of the embodiment of  FIG. 1 , depicting an exit angle, entry angle, and angle of reflection. 
         FIG. 4  depicts an exemplary emitter for use in the embodiment of  FIG. 1 . 
         FIG. 5  depicts an exemplary detector for use in the embodiment of  FIG. 1 . 
         FIG. 6  depicts an exemplary related device for use with the embodiment of  FIG. 1 , including a variety of positions in which the emitter of  FIG. 4  and detector of  FIG. 5  may be located. 
         FIG. 7  is a diagram of a circuit for modulating a presence detecting signal with other control signals. 
         FIG. 8  depicts an exemplary two-dimensional emitter array and exemplary two-dimensional detector array. 
         FIG. 9  is a flowchart depicting an operation of an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     1. Introduction 
     Generally, one embodiment of the present invention takes the form of an apparatus for detecting a person&#39;s presence without requiring the person to provide auditory or tactile input. For example, an embodiment of the present invention may be incorporated into an electronic device, such as a desktop computer or notebook computer. The embodiment may employ a variety of radiation emissions to determine when a person enters the embodiment&#39;s field of detection and, in response to the person entering, activate the electronic device. This may prove particularly useful where, for example, the electronic device consumes significant power and/or may suffer deleterious effects if left active for too long. When used in a notebook or desktop computer, for example, the embodiment may minimize power consumption by permitting the notebook to sleep and yet provide convenience for a user by automatically waking the notebook as the user approaches. Not only does this eliminate any requirement for the user to tap a key, press a mouse button, or otherwise interact with the computer. 
     An approaching entity generally constitutes a “presence.” Embodiments of the present invention are configured to detect a presence and ignore nearby, stationary objects.
         2. First Embodiment of the Invention       

       FIGS. 1 and 2  depict a first embodiment  100  of the inventions placed in a notebook computer  105 . Here, the notebook computer is an example of a “related device.” Generally, the embodiment includes an emitter  110  and a detector  115 . Infrared beams  120  are projected by the emitter  110  and received by the detector  115  after reflecting from an object within the embodiment&#39;s detection field  125 . The detection field may be one-dimensional (linear), two dimensional (planar), or three-dimensional depending upon the configuration of the emitter and detector. Alternative embodiments of the present invention may emit a variety of radiation, such as ultraviolet light or any other light frequency. Yet other embodiments may employ acoustic reflection, such as SONAR, or a steered infrared laser in place of the emitter array described herein. 
     The infrared beams  120  projected by the emitter  110  define a volume of sensitivity, referred to herein as a “detection field”  122 . The exact dimensions of the detection field are determined by the radiation emitted and configuration of the emitter, and thus may vary between embodiments. One particular embodiment  100  employs a detection field  122  having a depth of approximately one and a half meters and a width of approximately three-tenths of a meter. The detection field  122  may be generally rectangular, or may resemble a truncated cone, with the embodiment at the smallest portion of the truncated cone. The depth of the detection field may be referred to as the field&#39;s “depth threshold.” 
     Although the embodiment  100  may employ a relatively deep detection field  122 , many embodiments may limit the depth of the field in order to reduce activations caused by people passing by the embodiment (and thus through the field) without intending to actually approach or use the embodiment or related device. By limiting the depth of the field, false positives caused by reflection and detection of the emitted beams  120  may likewise be reduced. One exemplary method to limit the depth of field  122  is discussed in more detail below. 
     3. Emitter 
       FIG. 4  depicts an exemplary emitter array  110 . The emitter  110  includes a number of light-emitting diodes  130  (LEDs). Each LED  130  projects infrared radiation as a series of beams  125  in a conical pattern. The infrared radiation passes through a lens  135 , which bends the beams and establishes a uniform exit angle θ  140 . Typically, the exit angle θ  140  may vary between −30° and 30° in ten degree increments, although alternative embodiments may vary the range of the exit angle, the incrementation of the angles, or both. 
     Although  FIG. 4  depicts a linear array of LEDs  130  in the emitter  110 , alternative embodiments may vary the number and configuration of the LEDs. For example, a single LED  130  may be used, or a matrix of LEDs may be used. Accordingly, while the shape and configuration of the LEDs will naturally affect the dimensions of the detection field  125 , it should be understood that different embodiments may employ any number of LEDs in any configuration without departing from the spirit or scope of the present invention. 
     As shown in  FIG. 3 , the emitter  110  may be placed at one corner of a notebook computer  105 , for example just above and to the left of the computer&#39;s display  145 . To continue the current example, a detector  115  may be positioned opposite the emitter  110 , such as to the right and above the computer&#39;s display  145 . By placing the emitter and detector at opposite ends of the computer, a relatively wide detection field may be established fairly simply. 
     4. Detector 
       FIG. 5  depicts an exemplary detector  115  for use in the present invention. The detector  115  includes a number of infrared sensors  150 , which may be of any type known to those of ordinary skill in the art. One exemplary sensor  150  is a photodiode. The detector generally is made of a series of infrared sensors configured to match the configuration of the emitter&#39;s LEDs  130 . Thus, if the emitter  110  includes 10 LEDs  130  arranged linearly, the detector  115  will include 10 sensors  150  in the same linear arrangement. 
     As with the emitter  110 , the detector  115  includes a lens. Here, however, the emitter lens  155  focuses all infrared beams  125  entering the lens to one of the sensors  150 . The sensor to which the beam is focused depends in part on the beam&#39;s entry angle φ  160 . Beams with entry angles within a first range will be focused to the first sensor, within a second range to the second sensor, and so on. The range of the entry angle φ  160  corresponding to each sensor  150  is determined by the physical properties of the lens  155 , as known to those skilled in the art. Accordingly, different lenses  155  may be selected for use in different embodiments, and may be chosen at least in part based on the configuration of the sensors  150  in the detector  115 . 
     As with the exit angle  140 , the entry angle φ  160  typically varies between 30° and 30° in ten degree increments. Alternative embodiments may change the range of entry angles available, the incrementation thereof, or both. 
       FIG. 8  depicts an exemplary two-dimensional emitter  110  and detector  115 , each having the same number of rows and columns. Generally speaking, as each row of LEDs  130  in the emitter  110  activates, the corresponding row of the detector  115  is scanned to determine whether a reflected beam  125  is received by a sensor  150 . The embodiment  100  thus cycles through both the emitter and detector rows and columns, sequentially firing the LEDs and scanning the appropriate sensor rows Some embodiments may additionally scan a row of sensors  150  above and/or below the row corresponding to the firing LED  130 . In this manner, the embodiment may account for lens imperfections that would otherwise blur the emitted beam.
         5. Operation of the Embodiment       
     The general operation of the embodiment  100  will now be described. The emitter  110  projects the infrared beam  125  in a pulse train, cycling through each of the LEDs  130 . By employing a pulse train, the embodiment  100  may assure that infrared beams  120  emitted by the LEDs  130  do not interfere with one another, which may cause scattering, diffusion, and an inability to be reflected to the detector  115 . In one embodiment of the present invention, the emitter fires the LEDs in a twelve-pulse train at about 200 kilohertz. 
     The detector  115  receives a beam  125  or beams reflected from an object  165  within the detection field  122  at one of the sensors. (Alternative embodiments may receive a reflected beam at multiple sensors by varying the focusing lens&#39; physical properties, or by varying the distance between the focusing lens  155  and sensor array.) The detector receives the beam, demodulates it, and stores the data on the detected beam. Typically, the stored data will include a signal/beam&#39;s angle of exit θ  140  and angle of entry φ  160 . For reference, stored data with these parameters may be referred to as “signal (θ,φ).” The signal data may be stored, for example, in a memory or on a computer-readable medium. The embodiment  100  employs synchronous demodulation, as known in the art, to screen noise and determine the actual signal received. Insofar as synchronous demodulation is a commonly-known technique, this paper provides no further discussion thereof. 
     As previously mentioned, it may be advantageous to limit the field of detection for the present embodiment  100 . One manner of limiting the field  122  involves determining a minimum angle of reflection  170  for which a body will be considered within the field. As shown in  FIG. 3 , any object reflecting an infrared beam from the emitter to the detector reflects the beam at an angle β  170 . The angle of reflection may be determined by the embodiment as follows. 
     For every received signal  125 , an angle of exit θ  140  and angle of entry φ  160  exist. As previously mentioned, these angles are detected by the sensors  150  and stored with the signal data. Given the angles, the angle of reflection β  170  may be determined. (See  FIG. 3  for one example of the various angles.) The angle of reflection β equals the exit angle θ plus the entry angle φ. Calculation of the angle of reflection  170  permits triangulation of the object  165  reflecting the infrared beam. That is, given an exit and entry angle, as well as an angle of reflection, the exact position of the body may be calculated. A single point within the detection field  122  may provide each angle of reflection for a given combination of entry and exit angle. 
     The angle of reflection  170  may be used to determine whether the object  165  from which the beam  125  is reflected is within the depth field  122 . (The infrared beams, in many cases, may project further than the desired depth field, permitting reflection from targets that are actually outside the desired depth field.) A minimum acceptable reflection angle β  175  may be calculated by the embodiment  100 , based on the distance between the emitter  110  and detector  115  (i.e., width of the detection field) and desired depth of the detection field  122 . Generally, the minimum acceptable angle β  175  will occur when the infrared beam  125  emitted by the emitter  110  strikes the opposite corner at the maximum depth of the detection field  122 . This minimum acceptable angle is related to the depth threshold for the embodiment. In  FIG. 3 , this particular angle of reflection is labeled as β 2 . 
     To elaborate, presume the parameters of the detection field  122  are a width of 0.3 meters and a maximum depth threshold of 1.5 meters, as discussed above. Thus, the minimum acceptable reflection angle β 2   175  would equal the arctangent of the width divided by the depth. In mathematical terms:
 
β2 =A  TAN(0.3/1.5)
 
     or β 2  equals approximately eleven degrees. Accordingly, an angle of reflection  170  less than eleven degrees indicates a reflection from an object  165  outside the desired depth of the detection field  122 , while an angle of reflection greater than (or equal to) eleven degrees indicates a reflection of an infrared beam  125  from an object within the desired depth of the detection field. In this manner, the embodiment  100  may treat any beam reflected by an object outside the desired depth of the detection field as a false positive. Essentially, such reflected beams are ignored. 
     By limiting the maximum depth of the detection field  122  as described above, the embodiment  100  may prevent false activations of the related device  105  due to background movement. It should be noted that certain embodiments may conservatively estimate the minimum angle of reflection  175 . Such embodiments may, for example, reduce the minimum allowable angle of reflection, thus effectively extending or “padding” the depth of the detection field. Continuing the example above, an embodiment may determine the minimum angle of reflection  175  to be eleven degrees, but only ignore reflected beams  125  having an angle of reflection  170  less than nine degrees. 
     Although detection of objects within the detection field  122  and within the desired depth is useful, such detection may not suffice alone. For example, an emitted infrared beam  125  may reflect off a chair or other piece of furniture, a plant, or another stationary object  165  within the detection field and inside the depth threshold. Accordingly, it may be useful to provide some form of motion detection to screen out beams  125  reflected from stationary objects  165 . In such an embodiment, the related device  105  will not wake, or perform any triggered function, unless both the depth threshold and motion detection tests are satisfied. 
     A variety of motion detection schemes may be used. For example, one or more sensors  150  may look for the reflected beam  125  to intermittently appear and/or disappear, such that the signal from the beam is not continuous. An interrupted or intermittent signal generally corresponds to a reflection from an object  165  that is not constantly in a single position. 
     Similarly, the embodiment  100  may determine whether a reflected signal is passed from one sensor  150  to another, either an adjacent or non-adjacent sensor. Where the reflected beam is detected sequentially by multiple sensors, it may correspond to an object moving through the detection field  122 . 
     As yet another option, the embodiment  100  may determine if a signal from a reflected beam  125  undergoes changes for at least a minimum period of time. In this manner, the embodiment  100  may acknowledge only signals received by the sensor  150  that continue to change for at least the minimum time, thus screening signals caused by reflections from objects  165  (including people) only briefly within the detection field  122  or immobile objects. Objects that only briefly occupy a volume within the detection field typically do not represent a person approaching the related device  105 , and thus should not actuate the device. 
     In one embodiment, the embodiment  100  may employ a lowpass filter to determine motion. For any reflected beam  125  having an angle of reflection  170  greater than the minimum angle of reflection, the embodiment may subject the corresponding signal to a lowpass filter. For example, an infinite impulse response filter may be employed to calculate a filter value for the signal, as follows:
 
Filtered signal (θ,φ)=[(1 /n )(signal (θ,φ))]+[(( n −1)/ n )(filtered signal (θ,φ)]
 
     The filtered signal value is calculated from the stored signal data, including the related exit angle  140  and entry angle  160 . Such a response filter acts as a lowpass filter, permitting only signal values below a threshold to pass. Given the value of the filtered signal, the embodiment may determine if the absolute value of the difference between the signal (θ,φ) and filtered signal (θ,φ) exceeds a threshold constant K. The constant K represents the minimum duration, in seconds, during which the signal must undergo some change in signal strength at the region of interest, or reflecting body. In one embodiment, K equals three seconds. Alternative embodiments may vary the constant K as desired. 
     If the aforementioned absolute value exceeds or equals K, the embodiment  100  may determine the reflecting object  165  constitutes a presence, and actuate the related device  105 . If the absolute value is less than K, then the embodiment may determine the reflecting object does not constitute a presence, in which case the related device is not actuated and the reflected beam is ignored. 
     Further, the embodiment  100  may optionally compare current values of stored signals and/or reflected beam data to historical signals and/or reflected beam data. By comparing current signal data (such as angles of reflection  170  or other angles, filtered signal values, and so forth) to stored signal data previously determined to indicate a presence, the embodiment  100  may determine whether the current signal data indicates a presence. The embodiment may employ such historical analysis in addition to, or in lieu of, the motion detection and/or object detection operations discussed herein. 
       FIG. 9  is a high-level flowchart showing the general operations executed by one particular embodiment of the present invention. First, in operation  900 , at least one LED  130  emits a beam  125  of infrared radiation at an exit angle θ  140 . In operation  910 , a sensor  150  receives a beam reflected from an object  165 . In one embodiment, every sensor in the detector array  115  is sampled at each illumination of every single LED in the emitter  110 . Since the infrared beam is substantially instantaneously reflected, in this manner the detector receiving the reflected beam may be matched to the LED producing the beam. Thus, both the exit angle θ and entry angle φ may be relatively easily determined. In other words, for each LED activation in the emitter  110 , all sensors  150  in the detector  115  are scanned to determine whether the activated LED&#39;s beam  125  is reflected. 
     In operation  920 , the reflected beam  125  is demodulated by the embodiment  100  and its signal data (including the exit  140  and entry  160  angles) stored. In operation  930 , the exit and entry angles are employed, as described above, to determine the beam&#39;s angle of reflection β  170 . 
     Once the angle of reflection β  170  is known, the embodiment  100  may determine in operation  940  whether the angle of reflection β exceeds the minimum angle of reflection  175 . If so, then the object  165  reflecting the beam  125  is within the depth threshold of the detection field  122 , and operation  960  is accessed. Otherwise, the reflecting object is too far away and the reflected beam is ignored in operation  950 . 
     Following operation  950 , the embodiment  100  returns to operation  900  and emits another beam  125  from at least one LED  130  in the emitter  110 . Typically, the LED from which a beam is emitted in a subsequent iteration of operation  900  is the LED adjacent to the one employed in the immediately-finished iteration of the method of  FIG. 9 . In other words, each pass through the method of  FIG. 9  causes a different LED  130  to emit an infrared beam  125 . 
     In operation  960 , the embodiment  100  determines whether the signal (or reflected beam  125 ) has undergone a change of state for a sufficient time. The exact manner for making such a determination is discussed above. If the signal&#39;s change exceeds the threshold time K, then operation  970  is accessed. Otherwise, the embodiment executes operation  950 , as discussed above. 
     In operation  970 , the embodiment  100 , having detected a presence, activates the related device  105 . This activation may take many forms, from turning the device on to instructing the device to perform a function, to accessing information stored in the device, and so on. As an example, the embodiment  100  may wake the related device  105  from an inactive (“sleep”) mode, powering up the device to an active state. 
     Following operation  970 , the method of  FIG. 9  ends at end state  980 . 
     The various operations described with respect to  FIG. 9 , and in particular the determinations of operations  940  and  960 , may be performed by dedicated hardware or controlled by appropriate software, or a combination of the two. For example, an integrated circuit may be designed to carry out the logical operations described herein and control operation of the emitter and/or detector. 
     6. Operating Environment 
     Embodiments of the present invention may be operationally connected to, or incorporated within, any of a variety of electronic devices (including related devices  105 ). For example,  FIG. 6  depicts a number of possible locations  205  for the emitter  110  and/or detector  115  on the surface of a notebook computer. It should be noted that the emitter and detector may be collocated. 
     Yet other embodiments may be incorporated into different computing systems, such as desktop computers. Still other embodiments may be incorporated into a variety of other electronic devices, such as televisions, computer monitors, stereo equipment, appliances, and so forth. 
     Various embodiments of the present invention may be assembled as one or more integrated circuits incorporated into the operating environment. Further, components of the invention, such as the emitter and/or detector, may take the form of dedicated circuitry. 
     7. Additional Functionality 
     As may be appreciated by those skilled in the art, the present invention may be combined with other features or functions to provide enhanced value when incorporated into a related device  105 . For example, the detector  115  may be used not only to determine a presence by receiving a reflected beam  125  as described above, but also to receive infrared control signals from a remote control.  FIG. 7  depicts an exemplary circuit  200  for demodulating an infrared signal received at a photodiode or other sensor. The incoming signal may be demodulated with a reference voltage  210  to determine whether the signal comprises a reflected beam  125  generated by the emitter  110 . Similarly, the incoming signal may be demodulated with a 38 kilohertz reference sine wave  215  to generate output A, and a 38 kilohertz reference cosine wave  220  to generate output B. The combination of outputs A and B may comprise the infrared control signal. 
     In yet other embodiments, the detector  115  (or, for that matter, the emitter  110 ) may double as an ambient light detector. Many electronic devices, including notebook computers, employ an ambient light detector to adjust the brightness of a display to local light levels. A photosensitive chip may be masked such that a first portion of the chip&#39;s pixels, photodiodes, or other sensors  150  are sensitive to infrared light and a second portion of the chip&#39;s sensors are sensitive to visible light. The infrared-sensitive sensors may function to receive reflected signals  125 , while the visible light-sensitive sensors may function to detect ambient light. The chip may be masked with two different optical filters to create the desired sensitivities. In some embodiments, one or more sensors  150  may not be optically masked at all. 
       FIG. 8  generally depicts a two-dimensional emitter  110  and detector  115  having n rows. The detector may be masked in a variety of patterns to perform the multiple functions of ambient light and infrared signal detection. For example, the detector may be masked in a checkerboard pattern, with alternating sensors  150  detecting ambient light and infrared signal. Alternatively, the outer rows and columns of the detector may be sensors configured to detect infrared, while the interior sensors may be configured to detect ambient light. 
     In yet another embodiment, the detector  115  may simultaneously function as a camera for videoconferencing. In the manner discussed above, a first set of sensors  150  may be masked to function as a video camera, while a second set of sensors is masked to detect reflected infrared beams. 
     In still another embodiment, the infrared beam  125  emitted by the LEDs  130  may be modulated (and later demodulated) with a wave of a known frequency and phase in such a manner as to provide depth mapping of the object reflecting the beam. Thus, the detector may serve not only to determine a presence, but also to provide and/or reconstruct a three-dimensional depth map of the object. 
     By incorporating such additional functionality into the emitter  110  and/or detector  115  of the present invention, the number of openings or ports provided in the related device  105  may be minimized. Further, the incorporation of multiple functions into a single chip or array may minimize the overall footprint necessary to perform such functions, as compared to devices employing dedicated elements for each function. Where space is at a premium, as in notebook computers, such spatial minimization may be valuable.
         8. Conclusion       

     Although the present embodiment has been described with reference to particular methods and apparatuses, it should be understood that such methods and apparatuses are merely exemplary. Accordingly, the proper scope of the present invention is defined by the appended claims, and those of ordinary skill in the art will be able to conceive of variations on the methods and apparatuses set forth herein without departing from the spirit or scope of the present invention.

Metadata:
Filing Date: 20050623
Publication Date: 20091006
Grant Date: 20091006
Priority Date: 20050623
Inventors: HOTELLING STEVE P.
BRENNEMAN SCOTT A.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01S17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01V8/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01V8/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S17/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S17/48", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 37566916