PATENT DOCUMENT

Publication Number: US-9247611-B2
Application Number: US-47606709-A
Country: US
Kind Code: B2

Title: Light source with light sensor

Abstract:
There are provided systems, devices and methods for operating a light source with a light sensor to provide a desired light output. In particular, in one embodiment, there is provided a light control system. The light control system includes a light source and a light sensor that share a common light pathway. Additionally, the light control system includes a controller electrically coupled to the light source and the light sensor. The controller operates the light source and the light sensor alternatively during a periodic cycle having a frequency of approximately 60 Hz or greater to achieve a desired visual effect based on ambient lighting conditions.

Claims:
The invention claimed is:  
     
       1. A light control system for an electronic device, comprising:
 a light source; 
 a light sensor separate from the light source and configured to sense ambient light levels; 
 a light pathway shared by the light sensor and the light source; 
 a controller communicatively coupled to the light source and the light sensor, the controller configured to alternately activate the light source and the light sensor during a periodic cycle to illuminate at least a portion of the electronic device, wherein the controller activates the light sensor after a predetermined delay following deactivation of the light source and wherein the controller dynamically adjusts an output of the light source during the periodic cycle based on a sensed amount of ambient light present after the predetermined delay; and 
 the light source and light sensor are disposed on a planar surface of a common substrate. 
 
     
     
       2. The light control system of  claim 1  wherein dynamically adjusting the output of the light source comprises adjusting the brightness of the light source by reducing a length of time the light source is activated. 
     
     
       3. The light control system of  claim 2  wherein the controller adjusts the brightness of the light source to match the sensed amount of ambient light. 
     
     
       4. The light control system of  claim 1  wherein the light source comprises a top-firing LED. 
     
     
       5. The light control system of  claim 1  wherein the light source is a side firing LED and the light sensor and light source are located in different axes relative to a longitudinal axis of light pathway. 
     
     
       6. The light control system of  claim 1  wherein the controller adjusts the brightness of the light source so that the surface of the light source appears painted in the sensed ambient light conditions. 
     
     
       7. The light control system of  claim 1  wherein the light source comprises a multicolored LED. 
     
     
       8. The light control system of  claim 1  wherein the light source comprises two or more LEDs and wherein at least one of the two or more LEDs function as the light sensor. 
     
     
       9. The light control system of  claim 1  wherein the light sensor comprises one of a photodiode, a phototransistor, or a photodiode and an amplifier. 
     
     
       10. The light control system of  claim 1  wherein the light sensor comprises one or more narrowband photosensitive devices. 
     
     
       11. The light control system of  claim 1  wherein the light sensor comprises a broadband photosensitive device. 
     
     
       12. The light control system of  claim 1  comprising a master controller, wherein the master controller is configured to provide control signals to the controller. 
     
     
       13. The light control system of  claim 1  wherein the light source and light sensor are component parts of a single package. 
     
     
       14. A method of operating a light control system for an electronic device, comprising:
 providing a periodic control signal; 
 activating a light source positioned on a planar surface of a substrate during a first portion of the control signal; 
 activating a light sensor that is separate from the light source and positioned on the planar surface of the substrate during a second portion of the control signal to determine lighting conditions surrounding the electronic device, the light source and the light sensor positioned beneath a surface of the electronic device and sharing a common light pathway, wherein activating the light sensor during a second portion of the control signal comprises:
 providing a first predetermined time delay before actuation of the light sensor and after deactuation of the light source; and 
 providing a second predetermined time delay after deactuation of the light sensor and before actuation of the light source; and 
 
 during the first portion of the control signal, dynamically adjusting an output of the light source based on the determined lighting conditions. 
 
     
     
       15. The method of  claim 14  comprising pulse width modulating the actuation of the light source during the first portion of the control signal to adjust the brightness of the light output by the light source. 
     
     
       16. The method of  claim 14  wherein actuation of the light sensor generates an analog signal correlative to the amount of ambient light, the method comprising converting the analog signal to a digital signal for determination of the amount of ambient light and actuating the light source to correspond with the determined amount of ambient light. 
     
     
       17. The method of  claim 14  comprising determining a color of the ambient light and actuating the light source to match the color of the ambient light. 
     
     
       18. A method comprising:
 measuring ambient light conditions by a light sensor positioned on a planar surface of a substrate and contained within a housing of a computing device; 
 adjusting a light output by one or more light sources positioned on the planar surface of the substrate to provide a visual effect for a surface of the computing device based on the corresponding measured ambient light conditions, wherein at least one of the one or more the light sources and light sensor share a common, non-reflected light pathway and at least one of the one or more light sources is separate from the light sensor; 
 recording the measured ambient light conditions and the corresponding adjusted light output; and 
 programming a device to:
 determine ambient light conditions; and 
 actuate the one or more light sources during an actuation cycle shared by the one or more light sources and the light sensor to provide a light output that visually appears as a constant light and corresponds to the determined ambient light conditions based on the recorded data, wherein the ambient light conditions are determined by actuating a light sensor during the actuation cycle after a predetermined delay from when the one or more light sources are no longer actuated during the actuation cycle, such that the one or more light sources appear to be continuously actuated for a time period. 
 
 
     
     
       19. The method of  claim 18  wherein adjusting the light output comprises pulse width modulating the one or more light sources to obtain a desired color and brightness output that corresponds to the ambient light conditions. 
     
     
       20. A light control system for a portable electronic device, comprising:
 a light source; 
 a light sensor separate from the light source and configured to sense ambient light levels, wherein the light sensor and the light source are co-located on a single planar substrate and a light pathway is shared by the light sensor and the light source, the light pathway being substantially perpendicular to the single planar substrate; 
 a cover having an optically transmissive aperture disposed over the single planar substrate, wherein light received at the light sensor passes through the optically transmissive aperture and light emitted from the light source passes through the optically transmissive aperture to create an optical effect for the portable electronic device; and 
 a controller communicatively coupled to the light source and the light sensor and adapted to alternately actuate the light source and the light sensor during a periodic cycle that includes a light source portion and a light sensor portion, wherein the controller dynamically adjusts an output of the light source during the light source portion of the periodic cycle based on a sensed amount of ambient light that is detected after a first predetermined delay following the light source portion and before a beginning of the light sensor portion. 
 
     
     
       21. The package as in  claim 20 , wherein the light source is actuated after a second predetermined delay following a de-actuation of the light sensor. 
     
     
       22. The package as in  claim 20 , wherein the light source is used as a status indicator of a computing device.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     The following related patent applications are hereby incorporated by reference in their entirety as if set forth fully herein: U.S. patent application Ser. No. 12/476,000, titled “Keyboard With Increased Control of Backlit Keys” and filed concurrently herewith; U.S. patent application Ser. No. 12/476,040, titled “User Interface Behaviors For Input Device with Individually Controlled Illuminated Input Elements” and filed concurrently herewith; and U.S. patent application Ser. No. 12/475,993, titled “White Point Adjustment For Multicolor Keyboard Backlight” and filed concurrently herewith. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates generally to light sources and, more particularly, to light sources with light sensors. 
     2. Background Discussion 
     Most electronic devices, such as computers, DVD players, DVRs, televisions, surround sound receivers, etc. have lighting elements to illuminate certain parts of the device. For example, many devices have status indicator lights that may indicate that the device is powered on, communicating with another device or performing a particular function, among other things. Typically the indicator lights are light emitting diodes (LEDs) that are typically only operated in two modes: on or off. Generally, when on, the LEDs provide a high level of luminance. In some ambient lighting conditions, the level of luminance may be distracting or inadequate. For example, if the electronic device is located in a bedroom, a bright indicator light may make it difficult to sleep. Additionally, if the electronic device is located near a television or a projection screen, the indicator light may distract from content being displayed on the television of projections screen, particularly if the room is darkened. 
     SUMMARY 
     Certain embodiments may take the form of systems, devices and/or methods for operating a light source to provide a desired light output. In particular, in one embodiment, a light control system includes a light source and a light sensor. The light source and light sensor share a common light pathway. Additionally, the light control system includes a controller electrically coupled to the light source and the light sensor that operates the light source and the light sensor alternatively during a periodic cycle having a frequency of approximately 60 Hz or greater. 
     Another embodiment is a method of operating a lighting system. The method includes periodically actuating a light source during a first portion of a periodic control signal operating at 60 Hz or greater. A light sensor shares the same light pathway with the light source and is actuated during second portion of the control signal to determine ambient lighting conditions. 
     Yet another embodiment is a method of manufacturing a lighting system that includes measuring ambient light conditions and adjusting a light output by one or more light sources to provide a desired visual effect for the corresponding measured ambient light conditions. A calibration table is generated that includes the measured ambient light conditions and the corresponding adjusted light output. A device is then programmed to operatively determine ambient light conditions and actuate light sources to provide the light output that corresponds to the determined ambient light conditions based on the data in the calibration table. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a light control system. 
         FIG. 2  illustrates a network switch that may operate as a host for the light control system in accordance with an embodiment. 
         FIGS. 3A and 3B  illustrate a portable computing device in accordance with an alternative embodiment. 
         FIGS. 4A and 4B  illustrate a light sensor and light source package in accordance with an embodiment. 
         FIGS. 5A and 5B  illustrate a light sensor and light source package in accordance with an alternative embodiment. 
         FIG. 6  is a flowchart illustrating a process for calibrating the operation of a light control system in accordance with an embodiment. 
         FIG. 7  is a plot illustrating a transition curve for light output relative to a determined level of ambient light. 
         FIG. 8  is a timing diagram for time division multiplexing actuation of a light sensor and a light source and also illustrates pulse width modulation of the light source to adjust the color and brightness output by a light source. 
         FIG. 9  illustrates a light source and light sensor array package in accordance with an alternative embodiment. 
         FIG. 10  is a schematic and block diagram illustrating a master and slave configuration for operating light sensor and light source arrays in accordance with an embodiment. 
         FIGS. 11 and 12  illustrate timing diagrams for the operation of the light source and light sensor arrays in a master and slave configuration in accordance with alternative embodiments. 
         FIG. 13  illustrates implementation of a light source as a light sensor in accordance with an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Generally, one embodiment takes the form of a system for operating one or more light sources to produce a desired visual effect based on the amount of ambient light to which the one or more light sources are exposed. The system includes one or more light sensors proximately located to the one or more light sources so that the light sensors share the same optical path as the light sources. A microcontroller time division multiplexes (TDM) the light sensor and the light source such that the light sensors are not influenced by light emitted by the light sources. Thus, the light sensors sense ambient light to determine the operating conditions of the light source. The controller adjusts the output of the light sources according to determined ambient conditions in which the light sources are operating to create the desired visual effect. 
     The visual effects may generally include adjusting the brightness and/or color of light output by the light source. In particular, the visual effects may include dynamic transitions such that as the ambient light change due to time of day, presence of light sources, shadows, indoor/outdoor locations, etc., color and intensity of the output light changes. For example, the output light may be adjusted to match the effects of the ambient light. That is, if the ambient light increases in brightness and turns a reddish hue, the output light may correspondingly increase in intensity and turn a reddish hue, for example. In an alternative embodiment, the light output may counter the ambient light such that if the ambient light becomes brighter and turns a reddish hue, the light output may dim and turn a greenish hue, for example. Several different algorithms, such as transitions and fade in/out based on linear, multi-linear, logarithmic or power laws, may be implemented to accomplish the dynamic changes. Examples of the various transition algorithms may be found in U.S. patent application Ser. No. 12/251,186, titled: Color Correction of Electronic Displays” and filed on Oct. 14, 2008, which is incorporated herein by reference in its entirety and for all purposes. 
     Turning to the figures and initially referring to  FIG. 1 , a block diagram for an embodiment of a lighting system  10  having a light sensor  12  and a light source  14  coupled to a controller  16  is illustrated. The controller  16  may be any microcontroller suitable for actuation of the light sensor  12  and the light source  14  in a pulse-width modulation manner. For example, in some embodiments, the controller  16  may be a model 8742 manufactured by Intel Corporation, or a PIC16F84 manufactured by Microchip, Inc. In other embodiments, the controller  16  may be part of a larger integrated circuit, such as a microprocessor capable of running in either master or slave modes. In yet another embodiment, the controller  16  may be a multi-channel LED driver with precise current setting and matching across all LED&#39;s being driven. In the multi-channel LED driver embodiment, the LED&#39;s would be driven with low-side field effect transistors (FET) internal to the controller  16  and the resistors  60  would not be used. Examples of multi-channel LED drivers include Linear LTC3220 or Ti TLC5940. 
     In one embodiment, the controller  16  may be coupled to a CPU of a host device. The host may be any device that implements lighting effects. Examples of possible hosts include, but is not limited to televisions, computers, VCRs, DVD players, BluRay Disc players, DVRs, network switches, etc. For example,  FIG. 2  illustrates a network switch  20  that includes a status light  22  that illuminates to indicate the status of the network switch  20 . For example, the status light  22  may illuminate to a green color to indicate that the switch  20  is powered on and operating normally. Other colors may indicate different stages of operation, i.e. yellow to indicate starting up, or may blink to indicate other states of operation for the switch  20 . Additionally, other parts of the switch  20  may be illuminated. For example, a surface or a surface containing a mark, such as mark  24  may be illuminated in accordance with the techniques disclosed herein to achieve a desired visual effect. 
     In another example embodiment, the lighting system  10  of  FIG. 1  may be implemented in a portable computing device  30  as illustrated in  FIGS. 3A-3B . Specifically, the lighting system  10  may be used to control the illumination of various status indicators, buttons, surfaces, etc., of the portable computing device  30 , including a power button  32  or battery power indicators  34 . Additionally, the lighting system  10  may be integrated into the display  36  of the portable computing device  30  to control the color and intensity of the display  36  or other light source of the computing device  30 . In particular, the light sensor  12  may be located behind the display  36  and may be actuated alternately with the display  34  so that the ambient conditions in which the display  36  is operating may be determined and the display  36  or other light source may be operated to provide a desired visual effect. As such, in one embodiment, the light source  14  may represent the display  36  of the computing device  30 . 
     Referring again to  FIG. 1 , the illustrated light sensor  12  includes a photodiode  40  with an amplifier  42 . A positive and negative rail voltage  44  and  46 , respectively, may be supplied to the light sensor  12  from the controller  16  for the operation of the amplifier  42 . An output  50  of the light sensor  12  is coupled to an analog-to-digital converter (ADC)  52  that may be part of the controller  16 . The ADC  52  converts analog signals generated by the light sensor  12  into a digital signal to be processed and/or interpreted by the controller  16  or a host. For example, the controller  16  may receive a converted digital signal and determine the brightness of ambient light in which the multicolored light source  14  is operating. The controller  16  may then adjust the output of the light source  14  to achieve a desired visual effect according to ambient light conditions that are determined in real time. Stated differently, the controller  16  may dynamically adjust the light output (both intensity and color) based on current lighting conditions in which a light source is operating. 
     In particular, each anode  60  of LEDs  62  in the light source  14  may be coupled to a common supply voltage  64 , while each cathode  66  is independently coupled to buffers  68  within the controller  16 . Thus, each of the LEDs  62  may be independently actuated to achieve a desired color and brightness. The controller  16  may be configured to operate the LEDs  62  according to a particular lighting and/or coloring scheme. In one embodiment, the controller  16  may be configured to follow a programmed color and lighting scheme. 
       FIGS. 4A-4B  illustrate an expanded view of a block diagram of the light source  14  and light sensor  12  in accordance with an embodiment. In particular, the light source  14  and light sensor  12  are included in a single package  70  (“package”) in  FIGS. 4A-4B . The light sensor  12  may include a photodiode, a phototransistor, an integrated phototransistor and amplifier, or any other suitable photo-sensitive device. Additionally, in some embodiments, more than one light sensor  12  may be integrated into the package  70 . For example, in one embodiment, multiple narrowband light sensors may be integrated into the package  70  and each light sensor may be sensitive in a different portion of the visible light spectrum. In one embodiment, three narrowband light sensors may be integrated into a single package: a first light sensor may be sensitive to light in the red region of the electromagnetic spectrum, a second light sensor may be sensitive in a blue region of the electromagnetic spectrum, and a third light sensor may be sensitive in the green portion of the electromagnetic spectrum, for example. The sensing frequencies of each narrowband sensor may also partially overlap, or nearly overlap, that of another narrowband sensor. In other embodiments, one or more broadband light sensors (not shown) may be integrated into the package  70 . Each of the broadband light sensors may be sensitive to light throughout the spectrum of visible light. The light may be filtered to determine the intensity of light at particular wavelengths or within certain wavelength ranges. 
     The light source  14  may be any suitable light source, including incandescent light, light emitting diodes (LED), organic LEDs, solid-state lighting devices, etc. Additionally, the light source  14  may include more than one light source so that the light source  14  may generate a desired visual effect. In some embodiments, the light source  14  may include a multicolor LED. For example, the light source  14  may be a top firing red, green and blue (RGB) LED that emits red, green and blue light. 
     The light emitted from the light source  14  and the light sensed by the light sensor  12  may pass through a clear opening  72  or an aperture in a cover  74  of the package  70 . Additionally, the package  70  may include other layers  76  to diffuse, mix or shape the light. Specifically, for example, the layers  76  may include light guides, lenses, filters, holographic diffusers, etc. Such devices are known in the art and may implemented to achieve a desired effect. In some embodiments, for example, the lenses, light guides, filters, holographic diffusers may be made of glass or plastic, such as acrylic plastic. 
       FIG. 4B  is a cross-sectional view of the package  70 . As illustrated, the light sensor  12  and the light source  14  may be co-located or located in close proximity to each other and may be configured to receive and emit light, respectively, in the same light path. This allows the light sensor  12  to sense the same or approximately the same ambient light as that to which the light source  14  is exposed. Hence, the light sensor  12  may be used to determine the ambient light conditions in which the light source  14  is operating. 
       FIGS. 5A-5B  illustrate a light source and light sensor package  80  in accordance with an alternative embodiment. In particular, whereas the embodiment illustrated in  FIG. 4A  shows a top-firing LED, package  80  of  FIG. 5A  includes a side-firing LED  82 . The use of the side-firing LED  82  may allow the light sensor  12  to be positioned in a plane below the plane in which the side firing LED  82  operates an receive light through an aperture through which light from the LED  82  exits the package  80 , as can be seen in the cross sectional view shown in  FIG. 5B . As with the light source  14 , the side-firing LED  82  may include one or more LEDs, and/or may emit light having one or more colors of the visible light spectrum. 
     Although both top-firing and side-firing LEDs have been discussed and shown in the figures, it should be understood that they are provided as examples of potential light sources and other light sources may be possible and/or desirable. Additionally, while the light sources and the light sensors have been described as being combined in single packages  70  and  80 , it should be understood that the light sources  14  and light sensors  12  may be packaged separately but co-located so that a common window is used for receiving light at the light sensor and for light emitting from the light source. As such, each of the following described embodiments may be implemented with top-firing LEDs, side-firing LEDs, or any other suitable light source and the light sources and light sensors may be packaged together or otherwise co-located. Additionally, in some embodiments, the light sources  14  and light sensors  12  may be spatially separated, i.e., not co-located. 
     One possible visual effect that may be produced may be referred to as “constant contrast ratio” illumination. Constant contrast ratio illumination refers to adjusting the brightness of the light source  14  such that in particular ambient light conditions the window  72  or part of a surface that is illuminated by the light source  14  appears to have the same brightness as a surrounding non-illuminated surface, thereby making the illuminated window  72 , or part of the surface, appear as if it is painted or printed on a surrounding surface, rather than illuminated. Thus, the light source  14  does not appear to be glowing. 
     In order to achieve this effect, a calibration may be performed.  FIG. 6  illustrates a flowchart representing the calibration process  90 . The process  90  begins by measuring ambient light with the ambient light sensor  12  (operation  92 ). Multiple measurements may be taken throughout a range of operating conditions to obtain a representative data sets. The process continues by adjusting the color and brightness of the light source to achieve the close resemblance to a reference surface, such as the surface of the device near the window  72 , for example (operation  94 ). The ambient light conditions and the corresponding output brightness and color are then recorded into a calibration table (operation  96 ). Different calibration tables may be recorded for particular sets of ambient light conditions and desired visual effects. Additionally, where multiple colors are used, the setting of each color is recorded independently so that the desired effect may be reproduced. After calibration tables are generated, the calibration table may be programmed into the controller  20  and the controller  20  is programmed to use the calibration table for driving the LEDs to an corresponding brightness and color output based on a determined ambient light (operation  98 ). One of many possible interpolation algorithms, i.e., linear, logarithmic, exponential, etc., may be used to determine an appropriate output for ambient lighting that does not correspond directly to points of the calibration table. 
       FIG. 7  illustrates a plot  100  of example data points (shown as “x”) of a calibration table. The horizontal axis  102  represents an ambient light level having a scale relative to a maximum level that may be detected. The vertical axis  104  represents the brightness of the light sources relative to a maximum brightness level. Each data point is generated by determining the ambient light level and then determining an appropriate brightness and color level for the light source to achieve the desired effect, such as constant contrast ratio, for example. As the light source  14  may include more than one color and as each color may be independently controlled to achieve a desired color and brightness output, there may be multiple points, each having a unique brightness and color, for each level of ambient light. Once sufficient data points have been collected to establish a range of data from a minimum to a maximum ambient light level with each point offset from its neighbors by no more than a maximum allowable interval, the data points may be programmed into a controller so that the controller may operate the light sources according to the desired visual effect based on the determined amount of ambient light. 
     In order to operate light source  14  in close proximity with the light sensor  12  without the light sensor  12  being influenced by the output of the light source  14 , a time division multiplexing (TDM) scheme is implemented by the controller  16  to operate the light sensor  12  and the light source  14 . Additionally, a pulse width modulation (PWM) scheme may be implemented to allow the controller  16  to control the brightness and color output of the light source  14 , as discussed below. 
       FIG. 8  is a timing diagram  110  showing an example TDM and PWM scheme that may be implemented by the controller  16  to allow for sequential operation of the light source  14  and light sensor  12  in close proximity of each other. A first line  112  located at the top of the diagram  110  illustrates the periodicity of the TDM scheme. In particular, a single cycle  113  (period T) in the TDM scheme may include a light source portion (T_LED)  115  and a light sensor portion. The light source portion (T_LED)  115  of the period T may be defined as the time when the top line  112  is high (e.g., in a digital system a “one” output) and during which the light source  14  may be actuated. That is, one or more of the individual LEDs  62  of the light source  14  may be actuated during the light source portion (T_LED) of the period T. Additionally, when the first line  112  is low (e.g., in a digital system a “zero” output) the light sensor may be actuated and, hence, may be defined as the light sensor portion of the period T. The length of time of the period T may be selected so that the human eye is unable to detect light flicker and the light source appears to be continuously actuated. For example, the frequency (1/T) may be approximately 60 Hz or greater, although other embodiments may have lower frequencies such as 55 Hz or even lower. 
     The second line  114  in the timing diagram  110  corresponds to actuation of the light sensor  12 . The light sensor  12  is actuated during the light sensor portion of the period T and when the second line  114  is high, i.e., during time T_ALS. As can be seen, the light sensor  12  is not actuated for the entire light sensor portion of the period T. Specifically, there is a delay D 1  between the beginning of the light sensor portion of the period T and actuation of the light sensor  12 . Similarly, there is a delay D 2  between de-actuation of the light sensor  12  and the beginning of the light source portion T_LED of the period T. The delays D 1  and D 2  may result from latency between the time a command is issued from the controller to when the sensor is fully operative and additionally may allow for the light emitted from the light source  14  to disperse prior to actuation of the light sensor  12 . Hence, the delays D 1  and D 2  may help to ensure that light emitted from the light source  14  does not influence the light sensor  12 . The time allotted for the light sensor portion of the period T may be selected based upon the sensitivity of the light sensor being implemented and the response time of the light sensor, as well as the conversion speed of the ADC  52  of the controller  16 . A maximum time for the light sensor (T_ALS) is chosen so that it is less than the period T minus the time required for light source actuation (T_LED) minus the time for the delays D 1  and D 2 . 
     The third, fourth and fifth lines  116 ,  118 , and  120  in the timing diagram illustrate the actuation of the LEDs  62 . As can be seen, the actuation of each of the respective LEDs occurs during the light source portion (T_LED) of the period T. As each of the LEDs may be independently controlled, the LEDs may be actuated for different lengths of time and during different portions of the light source portion (T_LED) of the period T. The pulse width modulation of the light source, i.e., the length of time that a particular LED is actuated, determines the brightness of the light source  12  perceived by a viewer. The brightness of any given light source may be adjusted downward from 100 percent brightness based on the length of time the light source is actuated, where 100 percent brightness (or full brightness) is achieved by actuation of the light source for the entire light source portion (T_LED) of the period T. Therefore, if a particular LED is to be 75 percent of full brightness, for example, the length of time of actuation of that LED will be 75 percent of the light source portion (T_LED) of the period T. 
     In embodiments where the light source  14  includes more than one color emitter, such as a red, green and blue (RGB) LED, the actuation time of each LED can control the brightness, color scheme, and intensity of the light emitted by the light source  14 . For example, in one embodiment the lines  116 ,  118  and  120  may represent a red LED (third line  116 ), a green LED (fourth line  118 ) and a blue LED (fifth line  120 ), respectively. In the illustrated example, the third line  116  represents a significantly longer actuation time than either fourth or fifth lines  118  and  120  and, as such, the light seen by a viewer may have a reddish hue. 
       FIG. 9  illustrates implementation of an array  130  of light sources  14  and light sensors  12 . The array  130  may be implemented to illuminate and provide visual effects to a larger surface than the previously described embodiments. Additionally, the array  130  may provide for a diverse field of visual effects based on the determined ambient light for the illuminated surface. As illustrated, the light sensors  12  and the light source  14  may be located under a single surface  132  that is to be illuminated. In one embodiment, the surface  132  may be entirely translucent. In other embodiments, the surface  132  may include a clear window  134  which may be illuminated or through which the light from the light sources  14  may shine. Additionally, as with other embodiments, other layers  76  may be used to diffuse, mix or shape the light. Specifically, for example, light guides, lenses, filters, holographic diffuses, etc. may be positioned between the surface  132  and the light sources  14  and light sensors  12 . In one embodiment, the array  130  may be controlled by a single controller  16 , as discussed above, to operate the light sources  14  and light sensors  12  in a TDM and PWM manner to achieve a desired effect. In an alternative embodiment, multiple controllers are implemented to operate the array  130 , with each controller controlling a different number of light sources and/or light sensors. 
       FIG. 10  illustrates a block diagram  140  of an embodiment having a master microcontroller  142  configured to control an arbitrary number K slave controllers in a master-slave configuration. For example, a slave controller  144  may control the actuation of N light sources  146  and M light sensors  148 . In some embodiments, additional slave controllers  150  and  152  may control actuation of other arrays of light sources and light sensors (not shown). In other embodiments, the master controller  142  may also control an array of light sources and light sensors. Further, in yet other embodiments, there may be multiple “slave” controllers and no master controller  142 . Rather, the multiple slave controllers may be programmed to act independently from the others and they each may receive a sync pulse (T_sync) from a simple timing circuit (not shown) or a clock generation circuit (not shown). 
     Several different arrangements are possible for arrayed light sensors and light sources. In general, N light sources and M ambient light sensors may be implemented for a particular application, where N and M may or may not be equal. For example, in one embodiment, there may be more light sources  146  than light sensors  148  and, as such, a single light sensor  12  may sense ambient light for more than one light source  14 . In other embodiments, there may be the same number of light sensors  148  as light sources  146  or even more light sensors  148  than light sources  146 . Additionally, in one embodiment, one controller may be dedicated to operating light sources and another controller may be dedicated to operating the light sensors. 
     The array  130  ( FIG. 9 ) may be useful for providing a visual effect referred to as a “painted light surface” in which the constant contrast ratio effect is implemented across a larger surface. In the painted light surface embodiment, each light source  14  in the array of light sources  146  is coupled to one or more light sensors, which may be integrated with or separate from the light source  14 . The light sources  14  may be placed underneath the surface  132  so that the light strikes the surface  132  when the light sources  12  are driven. The control of the light sources  146  may be calibrated so that a surface appears uniformly painted in a range of ambient light conditions, following the process set forth above with reference to  FIG. 6 . Specifically, the array  130  may be operated at different ambient lighting conditions and the light sources  14  individually may be adjusted so that the surface appears painted. The setting of the light sources  14  at the various ambient light settings may be recorded and used for reference when determining light source operation based on particular ambient lighting conditions. 
     The operation of the light sources  146  and the light sensors  148  of the array  130  is similar to that discussed above. In particular, each LED  62  of the light sources  146  may be individually controlled to provide a desired effect. In one embodiment, the anodes  60  of each of the LEDs  62  may be coupled together while the cathodes  66  of the LEDs  62  may be coupled independently to the controller  144 . Hence, each of the LEDs  62  may be independently controlled by the controller  144 . Additionally, each of the other controllers  150  and  152  may independently control light sources (not shown) to create a desired visual effect. 
     The multiple controllers  144 ,  150  and  152 , may be synchronized with a sync pulse. For example,  FIG. 11  illustrates a timing diagram  160  for operating the controllers in a master/slave configuration, where the master controller  142  may control the operation of some light sources and/or light sensors. As shown in a first line  162 , a sync pulse (T_sync) is included prior to the first period T. Upon receiving the synch pulse, each of the controllers  144 ,  150  and  152  may operate synchronously. The synchronization helps to prevent the light sensors  148  from being influenced by lights sources operated by any of the controllers. 
     In addition to providing the T-sync signal, in one embodiment the master controller  142  may provide the period T to the slave controllers  144 ,  150  and  152 . Alternatively, the slave controllers  144 ,  150  and  152  synchronize with the master controller  142  on either the up stroke or down stroke of T_sync and then provide their own periodic signal period T, as shown in  FIG. 12 . Specifically,  FIG. 12  illustrates a timing diagram  170  in accordance with an alternative embodiment where T_sync, illustrated as the first line  172  in  FIG. 12 , is provided independent of the period T. The sync signal is provided by the master controller  142  and the period T (line  174 ) is provided by each of the slave controllers  144 ,  150  and  152 . All of the other signals may operate as discussed above to achieve a desired effect. In an alternative embodiment, the sync pulse may be provided to the slave controllers  144 ,  150  and  152  by a simple timing circuit or clock generation circuit. Additionally, the slave controllers  144 ,  150  and  152  may be programmed to operate independently and, hence, the master controller may not be used. 
     In addition or alternatively, light sources may operate as the light sensors. As illustrated in  FIG. 13 , a light source  180  may operate as both a light source and a light sensor. Hence, there is no separate light sensor. As illustrated, the light source  180  may be a multicolor LED light, such as the RGB LED light source shown, or a monochromatic LED. Each LED  182  of the light source  180  may operate as a light sensor. In order to operate as a light sensor, the light source  180  may be biased in a non-conducting direction. That is, each LED  182  may be reverse biased. To reverse bias the LEDs  182 , amplifiers  184  are provided in a controller  186  that is configured to control the operation of the light source  180 . The amplifiers  184  are coupled in between an ADC  188  and the light source  180 . Specifically, inverting inputs  190  of the amplifiers  184  are coupled to the anodes  192  of the light source  180  and non-inverting inputs  194  of the amplifiers  184  are coupled to the cathodes  196  of the light source  180 . 
     Each LED  182  of the light source  180  has a leakage current that will dissipate normally either through the diode itself or the large input impedance of the micro-controller in the High-Z state (in the megaOhm range). This increases proportionally to the brightness or the level of ambient light. Thus, if the LEDs  182  are driven during the period T_LED and then reverse biased and sensed during the T_ALS period, the LEDs  182  may operate as both the light sensor and the light source. Additionally, in order to increase the sensitivity, results from sensing of multiple LEDs (such as each of the R, G, and B LEDs  182 ) can be added together, either in analog or in the digital domain. That is, light sensed by each of the LED  182  of the light source  180  may be added together to determine the amount of ambient light. The determined amount of ambient light may then be used to determine a corresponding light output for the determined ambient light conditions by referencing a calibration table, as discussed above. Thus, the controller  186  may operate the light source  180  to provide a dynamic, desired light output based on current ambient light conditions. 
     Although the present embodiment has been described with respect to particular embodiments and methods of operation, it should be understood that changes to the described embodiments and/or methods may be made yet still embraced by alternative embodiments of the invention. For example, alternative lighting schemes may be provided to achieve various visual effects in certain ambient lighting conditions not specifically described above. Further, yet other embodiments may omit or add operations to the methods and processes disclosed herein. Still other embodiments may vary the rates of change of color and/or intensity. Accordingly, the proper scope of the present invention is defined by the claims herein.

Metadata:
Filing Date: 20090601
Publication Date: 20160126
Grant Date: 20160126
Priority Date: 20090601
Inventors: PANCE ALEKSANDAR
KERR DUNCAN
BILBREY BRETT
SLACK BRANDON DEAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H05B45/22", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B45/22", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B33/0869", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05B33/0818", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/11", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B20/40", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05B47/11", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 43219432