PATENT DOCUMENT

Publication Number: US-9465442-B2
Application Number: US-201313773331-A
Country: US
Kind Code: B2

Title: Optical proximity sensor system having reduced sensitivity to distinct near-field optical effects

Abstract:
A portable electronic device including a proximity sensing device having an emitter and a detector. The electronic device further including a housing for containing the proximity sensing device which includes an optical interface forming a face of the housing through which radiation between the emitter and the detector pass. The optical interface may include an oleophobic coating which is selectively modified such that optical interference from an optical interface near-field object on the proximity sensing device is reduced without reducing a sensitivity of the proximity sensing device to a target near-field object.

Claims:
What is claimed is: 
     
       1. A portable electronic device comprising:
 a proximity sensing device having an emitter and a detector; 
 a housing for containing the proximity sensing device; and 
 an optical interface forming a face of the housing through which radiation between the emitter and the detector pass, wherein the optical interface comprises an oleophobic coating defining a first region and a second region over the optical interface, wherein the first region and the second region have a different optical property such that optical interference from an optical interface near-field object on the proximity sensing device is reduced without reducing a sensitivity of the proximity sensing device to a target near-field object. 
 
     
     
       2. The portable electronic device of  claim 1  wherein the optical interface near-field object is smudge formed at the optical interface. 
     
     
       3. The portable electronic device of  claim 1  wherein the target near-field object is an object the sensing device is designed to be responsive to. 
     
     
       4. The portable electronic device of  claim 1  wherein the optical interface comprises a glass window forming a display screen of the portable electronic device. 
     
     
       5. The portable electronic device of  claim 4  wherein the oleophobic coating is formed on an outer surface of the glass window. 
     
     
       6. The portable electronic device of  claim 1  wherein the first region comprises an opening in the oleophobic coating that is directly over one of the emitter or the detector. 
     
     
       7. The portable electronic device of  claim 1  wherein the first region is directly above the emitter or the detector and a glass cover is positioned over a portion of the oleophobic coating in the first region. 
     
     
       8. A portable multi-function personal device comprising:
 a proximity sensor system having:
 an optical interface cover; and 
 an optical emitter and an optical detector positioned below the cover, the cover having been treated to exhibit decreased surface tension on its top surface except for a proximity sensor area directly above the optical emitter and the optical detector where radiation from the optical emitter and the optical detector passes. 
 
 
     
     
       9. The portable multi-function personal device of  claim 8  wherein the cover is made of glass. 
     
     
       10. The portable multi-function personal device of  claim 8  wherein a top surface of the cover is treated with an oleophobic coating having openings in the proximity sensor area. 
     
     
       11. The portable multi-function personal device of  claim 8  wherein an oleophobic coating applied to a top surface of the cover is patterned to expose a plurality of smaller areas in the larger proximity sensor area. 
     
     
       12. The portable multi-function personal device of  claim 8  wherein an optically transparent film is positioned within the proximity sensor area. 
     
     
       13. The portable multi-function personal device of  claim 8  wherein an oleophobic coating and a glass cover are positioned within the proximity sensor area. 
     
     
       14. A proximity sensing system having a modified response to near-field optical effects comprising:
 a portable electronic device having an outer casing comprising an optically transparent face; 
 a proximity sensing device positioned within the outer casing, the proximity sensing device having an optical emitter and an optical detector facing the optically transparent face such that radiation from the emitter passes through the optically transparent face; and 
 an oleophobic coating formed on a side of the optically transparent face opposite the proximity sensing device, the oleophobic coating having at least one optically modified portion positioned over the optical emitter or the optical detector such that optical interference from an optical interface near-field object on the proximity sensing device is reduced without reducing a sensitivity of the proximity sensing device to a target near-field object. 
 
     
     
       15. The system of  claim 14  wherein the optical interface near-field optical object is a smudge formed on the oleophobic coating. 
     
     
       16. The system of  claim 14  wherein the optically modified portion does not modify a response of the proximity sensing device to a target near-field optical effect. 
     
     
       17. The system of  claim 14  wherein the optically modified portion is a patterned cut out formed in the oleophobic coating. 
     
     
       18. The system of  claim 14  wherein the optically modified portion has a different surface energy than the rest of the optically transparent face. 
     
     
       19. The system of  claim 14  wherein the optically modified portion comprises a transparent material capable of modifying a surface energy of the oleophobic coating. 
     
     
       20. The system of  claim 14  wherein the optically modified portion comprises a glass cover positioned over the oleophobic coating.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 61/760,971, filed on Feb. 5, 2013. 
    
    
     FIELD 
     An embodiment of the invention is directed to an optical proximity sensing device having reduced sensitivity to selective near-field optical effects at the device interface, more specifically an optical proximity sensing device having reduced sensitivity to smudge. Other embodiments are also described and claimed. 
     BACKGROUND 
     Portable handheld electronic devices, such as the iPhone multifunction device by Apple Inc., have a touch screen in their front face, where an earpiece speaker or receiver used for telephony is located. When the device is being held against the user&#39;s ear during a phone call, a proximity function automatically senses this condition using an infrared proximity sensing device that is built into the device, and on that basis turns off the touch sensitive display screen of the device. The proximity function can also automatically determine or measure when the device has moved away from the user&#39;s ear, in which case the touch screen is re-activated. This is achieved by measuring the signals of an infrared proximity sensing devices radiation emitter and complimentary radiation detector, where the emitter transmits an infrared signal that is reflected by a nearby object (e.g., the user&#39;s head) and picked up by the detector. A stronger received signal may be interpreted by the proximity function to mean that the object is closer, while a weaker received signal means the object is farther away. 
     There are two primary near-field optical effects that have an impact on performance of the proximity sensing device. The first effect is the proximity sensing device&#39;s response to near-field low-reflectivity targets, such as a dark target object. A dark target object is one that tends to absorb a greater amount of radiation than lighter objects, therefore the intensity of a return radiation ray reflected off of a dark target object may not accurately reflect the dark target object&#39;s location or proximity to the proximity sensing device. The second effect is the device&#39;s response when liquid impurities are deposited on the surface of the touch screen interface directly above the proximity sensing device, such as oil-based secretions from the user&#39;s skin. This is collectively referred to as ‘smudge response.’ In some cases, the touch screen interface may have a coating such as an oleophobic coating, which facilitates cleaning of these human secretions (i.e., smudge) off of the screen. This coating, however, can also cause the smudge to bead up and form flattened spheres. These flattened spheres can act as optical lenses or total internal reflecting cavities for infrared beams emitted by the radiation emitter. In such cases, the infrared beams are reflected back to the radiation detector without contacting any nearby object, providing a false indication of user presence. 
     Each of these competing near-field optical effects must, therefore, be balanced to maintain proper proximity sensing device operation. Since both are near-field optical effects, however, changes to the optical/geometrical design of the proximity sensing device, or the electronic device within which it is implemented, typically result in an increase (or reduction) of both effects on the same order of magnitude. Thus, if a sensitivity of the proximity sensing device to, for example, a dark target object is increased, the sensitivity to smudge response is also increased. An increase in smudge response, however, is not desirable. 
     SUMMARY 
     An embodiment of the invention is directed to balancing target near-field optical effects, specifically dark target effects, and smudge near-field optical effects to ensure proper proximity sensing device operation. In particular, it is desirable for a sensitivity of the proximity sensing device to smudge, also referred to generally herein as an optical interface near-field object, to be reduced while still maintaining the device&#39;s response to low reflectivity targets, referred to generally herein as target near-field objects. Thus, in one aspect, the invention is directed to reducing an optical interference caused by optical interface near-field objects (e.g., smudge) without reducing the device&#39;s response to target near-field objects (e.g., black hair). In one embodiment, this is done by selectively controlling or modifying a surface energy of an optical interface through which radiation from the proximity sensing device travels. The optical interface may, in some aspects, be a transparent face of an outer casing of the electronic device within which the proximity sensing device is integrated. The surface energy of the optical interface may be modified by, in some embodiments, forming openings in portions of an oleophobic coating formed on the optical interface, which are directly above the radiation emitter and/or radiation detector of the proximity sensing device. In other embodiments, the surface energy of the optical interface is modified by forming a transparent cover having a higher surface energy than the coating, over portions of the oleophobic coating directly above the radiation emitter and/or radiation detector. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. 
         FIG. 1A  is a cross-sectional side view of one embodiment of a sensing device. 
         FIG. 1B  is a cross-sectional side view of one embodiment of a sensing device. 
         FIG. 2A  is a top plan view of one embodiment of the sensing device of  FIG. 1A  and/or  FIG. 1B . 
         FIG. 2B  is a top plan view of another embodiment of the sensing device of  FIG. 1A  and  FIG. 1B . 
         FIG. 3  is a cross-sectional side view of one embodiment of a sensing device. 
         FIG. 4  is a top plan view of another embodiment of the sensing device of  FIG. 3 . 
         FIG. 5  illustrates one embodiment of an optical interface near-field optical effect on a sensing device. 
         FIG. 6  illustrates one embodiment of a target near-field optical effect on a sensing device. 
         FIG. 7  is a perspective view of a handheld device within which embodiments of a sensing device may be implemented. 
         FIG. 8  is a block diagram of a system in which embodiments of a sensing device may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
     In this section, we shall explain several preferred embodiments of this invention with reference to the appended drawings. Whenever the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the invention is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments of the invention may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description. 
       FIG. 1A  is a cross-sectional side view of one embodiment of a sensing device. In the illustrated embodiment, sensing device  100  includes a radiation emitter  102  and a radiation detector  104 . The radiation emitter  102  may generate and emit radiation in, for example, the infrared (IR) bands. Representatively, radiation emitter  102  may be a semiconductor radiation source such as a light emitting diode (LED). The radiation detector  104  may be configured to sense changes in the intensity of radiation emitted from radiation emitter  102 . For example, radiation detector  104  may detect a radiation beam emitted from radiation emitter  102  after it is reflected off of a nearby object (e.g., target near-field object  136 ). In this aspect, radiation detector  104  may provide a proximity sensing function. Representatively, radiation detector  104  may be a photodiode or other type of photodetector capable of sensing and converting IR radiation into a current or voltage that can then be processed by the device within which it is implemented to determine a proximity of the nearby object. In some embodiments, sensing device  100  may further include an ambient light sensor (ALS) integrated within radiation detector  104  or separate from radiation detector  104  to provide an ALS function to sensing device  100 . The ambient light sensor may detect an intensity of ambient light from the surrounding environment and based on the intensity of light sensed, the device within which sensing device  100  is implemented, may modify its operation (e.g., display screen functionality and/or lighting). 
     Radiation emitter  102  may be mounted or formed within a portion of a substrate  112  within a first compartment  106  formed over substrate  112 . Radiation detector  104  may be mounted or formed within a portion of substrate  112  within a second compartment  108 . In one embodiment, substrate  112  is a printed circuit board (PCB) having traces, wire bond pads and vias disposed thereon or therein to facilitate transfer of electrical signals between radiation emitter  102 , radiation detector  104  and the electronic device within which sensing device  100  is implemented. Radiation emitter  102  may also be electrically coupled to proximity driver circuitry  144  and radiation detector  104  may be electrically coupled to proximity detector circuitry  140 . The circuitry may be signal processing circuitry that allows signals associated with the radiation emitter  102  and radiation detector  104  to be used by the electronic device to modify its operation (e.g., turn a display screen off). 
     The first and second compartments  106 ,  108  may be formed on opposing sides of a mid wall  110 . Mid wall  110  extends from substrate  112  and prevents cross talk between radiation emitter  102  and radiation detector  104 . Cross talk refers to an occurrence in which stray light from an emitter is detected by the detector, thereby causing an undesired false signal mimicking a true proximity or object detection signal. Mid wall  110  may therefore be made of any type of material capable of blocking emitter stray signals from the detector, for example, a ceramic, a metal, a polyimide or other similar material opaque to IR radiation. 
     Sensing device  100  may further include optical element  118  and optical element  120 . Optical elements  118 ,  120  may be lenses fitted within openings  114 ,  116  formed within a top wall of each of compartments  106 ,  108 . Optical element  118  is positioned over radiation emitter  102  such that light emitted from radiation emitter  102  passes through optical element  118  to the ambient environment. Optical element  120  is positioned over radiation detector  104  such that radiation from radiation emitter  102 , which is reflected off a nearby object, can pass through optical element  120  to radiation detector  104 . Each optical element  118 ,  120  may be configured to transmit and refract the incoming or outgoing light beams in the desired direction. For example, in some embodiments, optical elements  118 ,  120  may be drum lenses which can concentrate the transmitted light and therefore increase the amount of light focused at the nearby object or radiation detector  104 . This is particularly advantageous in the case of proximity detection because it can increase proximity detection distances. It is to be understood, however, that although exemplary optical elements are described herein, such features are optional and may be omitted in some embodiments. 
     In some embodiments, an optical interface  122  may further be positioned over radiation emitter  102  and radiation detector  104 . Optical interface  122  may be formed from a translucent or semi-translucent material such that it does not substantially modify the optical characteristics of sensing device  100 . For example, in some embodiments, optical interface  122  is a glass (or plastic) window or cover which forms part of the portable electronic device in which sensing device  100  is implemented. For example, optical interface  122  may be a transparent face or cover of an outer casing of a mobile communications device which forms part of the display screen. Alternatively, optical interface  122  may be part of sensing device  100 . 
     A coating  130  may further be formed over optical interface  122 . In some embodiments, coating  130  is an oleophobic coating which modifies a surface energy at the interface between the sensing device and the ambient environment to help prevent oils and fluids from the user from sticking to optical interface  122 . For example, in some cases, optical interface  122  is made of a glass material. Glass has a relatively high surface energy and liquids such as oil and water exhibit a high degree of adherence to such high surface energy surfaces. These adhesive forces between the liquid and the glass surface can, in turn, cause the liquid to spread across the surface making it difficult to remove from the glass. Coating  130  may therefore be an oleophobic coating which has a lower surface energy than glass and therefore allows oils and fluids from a user (as a result of their respective surface tensions) to form beads of fluid over the coating, which are easier to remove. 
     These beads of liquid, also referred to herein as optical interface near-field objects  132 , however, can cause undesirable near-field optical effects at optical interface  122  (e.g., a smudge effect). In particular, optical interface near-field objects  132  may be reflective spheres formed at optical interface  122  which can reflect radiation emitted from radiation emitter  102  back toward radiation detector  104  (also known as false signals). In some cases, these false signals may have an intensity greater than, or similar to, an intensity of a radiation beam reflected off of a nearby target object, for example, the target near-field object  136 . The proximity sensing function of sensing device  100  will, in turn, interpret these false signals to mean that a target near-field object is present when it really isn&#39;t and inactivate certain features of the device (e.g., the touch screen). 
     In general, it is desirable for a sensitivity of sensing device  100  to optical interface near-field objects  132 , such as smudge or other beads of fluid, to be reduced while still maintaining a sensitivity of sensing device  100  to the target near-field object  136 . This is particularly important to a performance of sensing device  100  in cases where the target near-field object  136  has a low reflectivity, for example, a dark object such as black hair. Thus, in one embodiment, the near-field optical effects caused by optical interface near-field objects  132  and target near-field object  136  are balanced by selectively modifying coating  130 , and in turn optical interface  122 , to reduce an optical interference caused by optical interface near-field objects  132  while still maintaining a sensitivity of sensing device  100  to target near-field objects  136 . 
     In one embodiment, this may be done by modifying a surface energy of the surface areas directly above radiation emitter  102  and/or radiation detector  104  so that optical interface near-field objects  132  either do not form, or are reduced, within these regions. Representatively,  FIG. 1A  illustrates an embodiment in which openings  134 A and  134 B are formed within a proximity sensing area of coating  130 , which is directly above radiation emitter  102  and radiation detector  104 , respectively. In this aspect, a surface of optical interface  122  is exposed within openings  134 A and  134 B. As previously discussed, in cases where optical interface  122  is formed by a glass material and coating  130  is an oleophobic coating, optical interface  122  has a higher surface energy than coating  130 . Thus, areas within openings  134 A and  134 B have a higher surface energy than areas outside of openings  134 A and  134 B. As a result of this higher surface energy, optical interface near-field objects  132  do not form in this region and therefore do not cause optical interference with an incident radiation ray  138  or a redirected radiation ray  139  of sensing device  100 . 
     It is noted that although openings  134 A and  134 B are described as separate openings formed over each of radiation emitter  102  and radiation detector  104 , it is contemplated that the openings may be combined into a single opening over both radiation emitter  102  and radiation detector  104  or over only one of radiation emitter  102  and radiation detector  104 , for example, only over radiation emitter  102 . 
     Although  FIG. 1A  illustrates a substantially integrated proximity sensing device, it is contemplated that each of the sensing components need not be integrated within the same module. For example,  FIG. 1B  illustrates a cross-sectional side view of another embodiment of a sensing device having sensing components integrated within separate modules. Sensing device  200  is similar to sensing device  100  of  FIG. 1A  and includes substantially the same features except that in this embodiment, sensing device  200  includes a radiation emitter module  202  and a radiation detector module  204  which are formed as discrete units, instead of being integrated into the same proximity sensor module. Representatively, radiation emitter module  202  may include an optical element (e.g., optical element  118 ) and radiation emitter (e.g., emitter  102 ) electrically coupled to a substrate and proximity sensor circuitry  240 . The substrate may be a printed circuit board (PCB) having traces, wire bond pads and/or vias disposed thereon or therein to facilitate transfer of electrical signals between the radiation emitter and the electronic device within which sensing device  200  is implemented. In addition, radiation detector module  204  may include an optical element (e.g., optical element  120 ) and a radiation detector (e.g., detector  104 ) electrically coupled to a substrate (a PCB) and proximity sensor circuitry  240 . The radiation detector module substrate may be a different substrate than the radiation emitter module substrate such that the radiation emitter module  202  and the radiation detector module  204  can be placed at different levels, positions, regions, etc., of the electronic device within which the sensing device  200  is implemented. Proximity sensor circuitry  240  should be understood as including both radiation emitter circuitry and radiation detector circuitry that allows signals associated with the radiation emitter and the radiation detector to be used by the electronic device to modify its operation (e.g., turn a display screen off). 
     A mid wall  210  may further be provided to prevent cross talk between radiation emitter module  202  and radiation detector module  204 . Mid wall  210  may therefore be made of any type of material capable of blocking emitter stray signals from the detector, for example, a ceramic, a metal, a polyimide or other similar material opaque to IR radiation. 
     In some embodiments, an optical interface  222  may further be positioned over radiation emitter module  202  and radiation detector module  204 . Optical interface  222  may be substantially similar to optical interface  122  of  FIG. 1A  in that it can be formed from a translucent or semi-translucent material such that it does not substantially modify the optical characteristics of sensing device  200 . For example, in some embodiments, optical interface  222  is a glass (or plastic) window or cover which forms part of the portable electronic device in which sensing device  200  is implemented. For example, optical interface  222  may be a transparent face or cover of an outer casing of a mobile communications device which forms part of the display screen. Alternatively, optical interface  222  may be part of sensing device  200 . Moreover, since in this embodiment, radiation emitter module  202  and radiation detector module  204  are discrete units, optical interface  222  may have a stepped configuration to accommodate the different positions of radiation emitter module  202  and radiation detector module  204 . 
     A coating  230  may further be formed over optical interface  222 . In some embodiments, coating  230  is an oleophobic coating which modifies a surface energy at the interface between the sensing device and the ambient environment to help prevent oils and fluids from the user from sticking to optical interface  222 . Similar to coating  130  described in reference to  FIG. 1A , a surface energy of coating  230  may be modified at surface areas directly above radiation emitter module  202  and/or radiation detector module  204  so that optical interface near-field objects  232  either do not form, or are reduced, within these regions. Representatively,  FIG. 2A  illustrates an embodiment in which openings  134 A and  134 B (or openings  234 A and  234 B of  FIG. 1B ) are formed within a proximity sensing area of coating  130  (or coating  230  of  FIG. 1B ), which is directly above radiation emitter module  202  and radiation detector module  204 , respectively. In this aspect, a surface of optical interface  222  is exposed within openings  234 A and  234 B. 
       FIG. 2A  and  FIG. 2B  each illustrate a top plan view of embodiments of the sensing device of  FIG. 1A  and  FIG. 1B .  FIG. 2A  illustrates an embodiment in which openings  134 A and  134 B (or openings  234 A and  234 B) are cut-outs which open up an entire region of coating  130  directly above radiation emitter  102  and radiation detector  104 . In other embodiments, as illustrated by  FIG. 2B , openings  134 A and  134 B (or openings  234 A and  234 B) are patterned cut-outs in which less than the entire region of coating  130  directly above radiation emitter  102  and radiation detector  104  are open. For example, openings  134 A and  134 B may be formed by a pattern of circular openings formed within coating  130 . Although circular openings are illustrated, it is contemplated that the patterned cut-out may include several smaller openings of any size, shape and in any arrangement sufficient to reduce an optical interference caused by optical interface near-field objects  132 . For example, the pattern may be formed by scratches, hash marks, squares, elongated openings, or any other type of opening sufficient to reduce an optical interference caused by optical interface near-field objects  132 . It is believed that since the higher surface energy material of the underlying optical interface  122  is exposed to the ambient environment through the pattern of cut-outs, optical interface near-field objects  132  will not form, or will be reduced, within these regions directly above radiation emitter  102  and radiation detector  104 . 
     Openings  134 A and  134 B (or openings  234 A and  234 B) may be formed within coating  130  (or coating  230 ) in any manner. Representatively, in one embodiment, coating  130  (or coating  230 ) is an oleophobic coating which includes an oleophobic ingredient that can be bonded to optical interface  122 . The oleophobic ingredient is provided as part of a liquid material that is applied to optical interface  122  by a chemical deposition process and openings  134 A and  134 B are formed by a masking process. For example, in one embodiment, a masking material may be deposited onto portions of optical interface  122  directly above radiation emitter  102  and radiation detector  104  prior to depositing the oleophobic material used to form coating  130  (or coating  230 ) onto optical interface  122 . The masking material may be deposited in the size and shape of openings  134 A and  134 B. Next, the oleophobic coating material may be deposited over optical interface  122 , including the masking material. The masking material may then be removed leaving openings  134 A and  134 B within the desired regions of coating  130  (or coating  230 ). Alternatively, in other embodiments, openings  134 A and  134 B may be formed by a mechanical abrasion, chemical etching or selective patterning process after coating  130  (or coating  230 ) is formed on optical interface  122 . Regardless of the application process, it is to be understood that coating  130  (or coating  230 ) includes an oleophobic ingredient which is permanently bonded to optical interface  122  during a manufacturing process, prior to release of sensing device  100  or  200  into the field to a consumer. 
       FIG. 3  is a cross-sectional side view of one embodiment of a sensing device. Sensing device  300  is substantially similar to sensing device  100  described in reference to  FIG. 1A , therefore the description of features previously provided in reference to  FIG. 1A  are not repeated with respect to sensing device  300 ; however, they should be understood as applying to sensing device  300 . In addition to the previously discussed features, however, in this embodiment, optical covers  334 A and  334 B are formed over portions of coating  130  directly above radiation emitter  102  and radiation detector  104  to modify a surface energy within these regions. In particular, as previously discussed, optical interface near-field objects  132  (e.g., beads of liquid or smudge) will not form, or their formation will be reduced, on surfaces such as glass which have a high surface energy. Therefore, in this embodiment, coating  130  is formed over the entire optical interface  122 . Instead of forming openings over radiation emitter  102  and radiation detector  104 , optical covers  334 A and  334 B formed of a high surface energy material (e.g., glass) are placed on coating  130  directly above radiation emitter  102  and radiation detector  104 . Since optical covers  334 A and  334 B have a relatively high surface energy (as compared to coating  130 ), optical interface near-field objects  132  do not form, or are reduced, within these regions resulting in a reduction in the undesirable near-field optical effects (e.g., false signals) caused by optical interface near-field objects  132 . In addition, since there is less interference from optical interface near-field objects  132 , it is believed that a sensitivity of sensing device  100  to target near-field objects  136 , particularly dark target objects, may be improved. Although glass is provided as one example, optical covers  334 A and  334 B may be formed of any similarly optically transparent material having a high surface energy. 
     Each of optical covers  334 A and  334 B may have any thickness and dimensions sufficient to improve a performance of sensing device  300  as previously discussed. Representatively, as illustrated in  FIG. 4 , in one embodiment, optical covers  334 A and  334 B are of a size and shape (e.g., square) sufficient to cover a portion of coating  130  directly above each of radiation emitter  102  and radiation detector  104 . In addition, optical covers  334 A and  334 B are shown as substantially solid structures, however, it is contemplated that they may be patterned with cut-outs as previously discussed. 
     It is further noted that although optical covers  334 A and  334 B are used to modify the surface energy of an optical interface formed over a sensing device similar to that of  FIG. 1A , it is contemplated that optical covers  334 A and  334 B may further be used to modify the surface energy of an optical interface formed over sensing device  200  described in reference to  FIG. 1B . In other words, sensing device  300  could include discrete emitter and detector modules as described in reference to  FIG. 1B . 
       FIG. 5  illustrates an optical interface near-field optical effect (e.g., smudge) on a sensing device. In  FIG. 5 , the x-axis represents a distance of a target object from an optical interface (e.g., a glass window) and the y-axis represents an intensity of a return signal detected by the sensing device. A typical usage scenario is represented by signal  506 . As the target object approaches the sensor, incident rays from the emitter are reflected back to the detector, resulting in an increased return signal. The magnitude of the return signal increases as the target gets closer to the sensor. The proximity function is configured to have a predetermined release threshold  502  which triggers the proximity function to activate or deactivate various features of the device within which the proximity sensing device is implemented (e.g., the touch screen). For example, when the detected intensity signals are determined to be above release threshold  502 , the device features are deactivated, and when the return signals are below the release threshold  502 , it is interpreted as the target object having moved away from the sensor interface and the device features are activated. An alternative implementation sets distinct thresholds for activation and deactivation. As previously discussed, optical interface near-field objects such as liquid beads caused by smudge result in additional reflected signal. This manifests as a high intensity signal  504 , which is offset from typical target response signal  506  by the amount of signal resulting from reflections associated with smudge (also known as smudge response). As can be seen from  FIG. 5 , an intensity of signal  504 , which is a false signal, is determined to be above release threshold  502 , therefore aspects of the sensing device will be deactivated at all times, even when there is no actual target object (e.g., a user&#39;s face). Such a response is undesirable. 
     By modifying the surface tension within areas of the surface overlying the radiation emitter and/or detector of the sensing device as previously discussed, however, optical interference from optical interface near-field objects can be reduced. This, in turn, results in a lower intensity return signal  508 , which more accurately reflects the proximity of near-field target objects to the sensing device. Since signal  508  passes below release threshold  502 , it is not interpreted by the proximity function as a target object and aspects of the associated electronic device can remain active. 
       FIG. 6  illustrates a target near-field optical effect on a sensing device. In  FIG. 6 , the x-axis represents a distance of an object, in this case a target near-field object (e.g. a user), from an optical interface (e.g., a glass window) and the y-axis represents an intensity of a return signal detected by the sensing device. In this case, the target near-field object may be a dark object (e.g., black hair), which poorly reflects radiation back to the sensing device. In this aspect, the intensity of the return signal  606  from the dark object is relatively low (as measured from baseline  610 ), in comparison to the return signal  604  from a lighter object at the same distance. If dark object return signal  606  falls below release threshold  602 , it is interpreted by the proximity function to mean that a target object is not nearby and therefore features such as the touch screen should remain active. Such a response, however, is undesirable since a target object is actually nearby. Typically, any optical design changes to the proximity sensor system that are intended to increase (or reduce) the sensor&#39;s response to either near-field targets (e.g., black hair) or optical interference near-field optical effects (e.g., smudge) will increase (or reduce) both by the same order of magnitude. The invention described herein solves this problem by selectively modifying the surface energy of the optical interface to reduce interference near-field optical effects without having an impact on target near-field optical effects. 
     Turning now to  FIG. 7 , this figure depicts an example embodiment of a portable handheld device  700  having a sensing device  712  implemented therein. Sensing device  712  may be substantially similar to the sensing devices previously discussed in reference to  FIGS. 1A-4 . In this illustration, a near end user is holding the device  700  in their hand. Sensing device  712  may be positioned within an outer casing of handheld device  700  near a front face of handheld device  700  so that it can sense a proximity of a user when the user draws the phone toward their face. It is contemplated, however, that sensing device  712  may be associated with other portions of handheld device  700 , for example, a bottom, a top or a side portion of handheld device  700 . In one embodiment, opening  702  may be associated with an earpiece receiver speaker  704 . In some embodiments, opening  702  may be configured to accommodate both an earpiece receiver speaker  704  and another component, such as an audio proximity sensing device. 
     Handheld device  700  may include various capabilities to enable the user to access features involving, for example, calls, text messages, voicemail, e-mail, the Internet, scheduling, photos, and music as shown on the touch screen display  706 . In addition, handheld device  700  may include a microphone  708  and speakerphone speaker  710  to allow for input and/or output of audio signals to and from handheld device  700 . When the user holds the handheld device  700  to their head during a call in, for example, the device handset mode, the earpiece receiver speaker  704  (which may be located at a top end portion of the handheld device  700 ) may be positioned against the user&#39;s ear. In that case, the sensing device  712  is situated in the general direction of the user. An emitter within sensing device  712  emits, for example, an IR light beam through the front face (which is formed by a transparent window or casing). The light beam is then reflected off of the user, and a based on the intensity of the beam, handheld device  700  can determine a proximity of the user, and for example, disable the touch screen display  706  when the handheld device  700  is determined to be close to the user&#39;s face. In addition, when sensing device  712  detects a relatively low ambient light intensity level, the display lighting may be reduced, for example, to conserve battery power. 
     It is to be understood that although a handheld device such as an iPhone® from Apple Computer, Inc. of Cupertino, Calif., is illustrated in  FIG. 7 , any of the sensing devices disclosed herein may be implemented within any number of electronic devices that could benefit from a light and proximity sensing device. For example, sensing device  712  may be implemented within a tablet computer, a notebook computer or other portable computing device. In still further embodiments, sensing device  712  may be implemented within a digital media player, such as a portable music and/or video media player, entertainment systems or personal digital assistants (PDAs), or general purpose computer systems, or special purpose computer systems, or an embedded device within another device, or cellular telephones which do not include media players, or devices which combine aspects or functions of these devices (e.g., a media player, such as an iPod®, combined with a PDA, an entertainment system, and a cellular telephone in one portable device). 
       FIG. 8  shows a block diagram of an embodiment of a wireless device  800  within which sensing device  712  may be implemented. In the illustrated embodiment, wireless device  800  is a wireless communication device. The wireless device  800  may be included in the device shown in  FIG. 7 , although alternative embodiments of handheld device  700  may include more or fewer components than the wireless device  800 . 
     Wireless device  800  may include an antenna system  802 . Wireless device  800  may also include a radio frequency (RF) transceiver  804 , coupled to the antenna system  802 , to transmit and/or receive voice, digital data and/or media signals through antenna system  802 . 
     A digital processing system  806  may further be provided to control the digital RF transceiver and to manage the voice, digital data and/or media signals. Digital processing system  806  may be a general purpose processing device, such as a microprocessor or controller for example. Digital processing system  806  may also be a special purpose processing device, such as an ASIC (application specific integrated circuit), FPGA (field-programmable gate array) or DSP (digital signal processor). Digital processing system  806  may also include other devices to interface with other components of wireless device  800 . For example, digital processing system  806  may include analog-to-digital and digital-to-analog converters to interface with other components of wireless device  800 . 
     A storage device  808 , coupled to the digital processing system, may further be included in wireless device  800 . Storage device  808  may store data and/or operating programs for the wireless device  800 . Storage device  808  may be, for example, any type of solid-state or magnetic memory device. 
     One or more input devices  810 , coupled to the digital processing system  806 , to accept user inputs (e.g., telephone numbers, names, addresses, media selections, etc.) or output information to a far end user may further be provided. Exemplary input devices may be, for example, one or more of a keypad, a touchpad, a touch screen, a pointing device in combination with a display device or similar input device. 
     Display device  818  may be coupled to the digital processing system  806 , to display information such as messages, telephone call information, contact information, pictures, movies and/or titles or other indicators of media being selected via the input device  810 . Display device  818  may be, for example, an LCD display device. In one embodiment, display device  818  and input device  810  may be integrated together in the same device (e.g., a touch screen LCD such as a multi-touch input panel which is integrated with a display device, such as an LCD display device). It will be appreciated that the wireless device  800  may include multiple displays. 
     Battery  814  may further be provided to supply operating power to components of the system including digital RF transceiver  804 , digital processing system  806 , storage device  808 , input device  810 , audio transducer  816 , sensor(s)  822  (e.g., sensing device  712 ), and display device  818 . Battery  814  may be, for example, a rechargeable or non-rechargeable lithium or nickel metal hydride battery. Wireless device  800  may also include audio transducers  816 , which may include one or more speakers, receivers and at least one microphone. 
     Sensor(s)  822  may be coupled to the digital processing system  806 . The sensor(s)  822  may include, for example, one or more of a light and/or proximity sensor. Based on the data acquired by the sensor(s)  822 , various responses may be performed automatically by the digital processing system, such as, for example, activating or deactivating the backlight, changing a setting of the input device  810  (e.g., switching between processing or not processing, as an intentional user input, any input data from an input device), and other responses and combinations thereof. It is noted that other types of sensors may also be included in wireless device  800 , such as an accelerometer, touch input panel, ambient noise sensor, temperature sensor, gyroscope, a hinge detector, a position determination device, an orientation determination device, a motion sensor, a sound sensor, a radio frequency electromagnetic wave sensor, and other types of sensors and combinations thereof. 
     Sensor(s)  822  may include one or more ALS or proximity sensors (e.g., sensing devices  712 ) which provide data relating to light (e.g., radiation emitted from radiation emitter  102 ). The data can be analyzed by digital processing system  806  to determine whether or not to adjust one or more settings of wireless device  800 . 
     While certain embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that the invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. For example, in embodiments where the emitter and the detector are separate modules, they may be mounted in separate portions of an electronic device and the optical interface having a modified surface tension may be two separate interfaces (e.g., two separate windows) formed over their respective emitter and detector modules and one or both of the interfaces may have a modified surface tension. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20130221
Publication Date: 20161011
Grant Date: 20161011
Priority Date: 20130205
Inventors: RAI ANANT
HOLENARSIPUR PRASHANTH S.
LEE ALEX M.
RUH RICHARD
Assignee: APPLE INC
CPC Classifications: [{"code": "G01S2007/4975", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S2007/52009", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S17/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S2007/4975", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01S2007/52009", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 51258839