PATENT DOCUMENT

Publication Number: US-9366752-B2
Application Number: US-201113243382-A
Country: US
Kind Code: B2

Title: Proximity sensor with asymmetric optical element

Abstract:
A proximity sensor may be mounted below a display cover layer in an electronic device. The proximity sensor may have a light source that emits light and a detector configured to detect reflections of the emitted light from nearby external objects. Optical structures may be interposed between the proximity sensor and the window in the display cover layer. The optical structures may include a first portion such as a convex lens that is configured to collimate light from the light source so that the light propagates along a surface normal to the display cover layer. The optical structures may also include a second portion such as a prism structure for deflecting uncollimated light away from the propagation axis of the collimated light.

Claims:
What is claimed is: 
     
       1. Apparatus, comprising:
 a light-based proximity sensor including a light source and a light detector; and 
 optical structures through which light from the light source passes, wherein the optical structures include light collimating structures and light deflecting structures, and wherein the light deflecting structures are configured to deflect light onto an object external to the apparatus. 
 
     
     
       2. The apparatus defined in  claim 1  wherein the light collimating structures include lens structures that collimate the light from the light source to produce collimated light. 
     
     
       3. The apparatus defined in  claim 2  wherein the collimated light propagates along a first axis and wherein the light deflecting structures are configured to deflect light from the light source to produce deflected light that propagates along a second axis that is oriented at a non-zero angle with respect to the first axis. 
     
     
       4. The apparatus defined in  claim 3  wherein the optical structures are configured such that the deflected light comprises uncollimated light. 
     
     
       5. The apparatus defined in  claim 4  wherein the light collimating structures comprise a convex lens. 
     
     
       6. The apparatus defined in  claim 5  wherein the light deflecting structures comprise prism structures. 
     
     
       7. The apparatus defined in  claim 6  wherein the convex lens and the prism structures are formed from a unitary molded plastic member. 
     
     
       8. The apparatus defined in  claim 3  wherein the light source comprises an infrared light-emitting diode and wherein the light deflecting structures comprise prism structures. 
     
     
       9. The apparatus defined in  claim 3  wherein the light collimating structures comprise a lens, wherein the light deflecting structures comprise a light reflector, and wherein the deflected light comprises uncollimated light. 
     
     
       10. The apparatus defined in  claim 9  wherein the light reflector comprises a prism. 
     
     
       11. The apparatus defined in  claim 1  wherein the wherein the light deflecting structures comprise a diffractive optical element. 
     
     
       12. An electronic device, comprising:
 a display layer; 
 a proximity sensor having a light source and a light detector; 
 a lens structure interposed between the light source and the display layer, wherein the lens structure is configured so that light emitted from the light source passes through the lens structure and the display layer and propagates along an axis; and 
 a light deflecting structure configured to deflect light from the light source through the display layer in a direction away from the axis. 
 
     
     
       13. The electronic device defined in  claim 12  wherein the light deflecting structures are configured to deflect the light from the light source to produce uncollimated light and wherein the display layer comprises a layer selected from the group consisting of: a display cover glass layer and a plastic display cover layer. 
     
     
       14. The electronic device defined in  claim 13  wherein the light source comprises a light-emitting diode. 
     
     
       15. The electronic device defined in  claim 14  wherein the lens structure comprises a convex lens structure and wherein the light deflecting structure comprises a prism. 
     
     
       16. The electronic device defined in  claim 15  wherein the prism and the convex lens structure form portions of a common molded plastic structure and wherein the electronic device further comprises an infrared-transparent ink layer on the display layer through which collimated light from the convex lens structure and deflected uncollimated light from the prism pass.

Description:
BACKGROUND 
     This relates generally to sensors and, more particularly, to proximity sensors for electronic devices. 
     Some cellular telephones contain proximity sensors. A proximity sensor can detect when a cellular telephone has been brought into proximity to a user&#39;s head. When the cellular telephone comes into close proximity to the user&#39;s head, touch screen functions in the cellular telephone can be deactivated to avoid unintentional touch input. 
     A cellular telephone proximity sensor generally contains a light-emitting diode that emits infrared light and a corresponding infrared light sensor that measures the amount of emitted infrared light that is reflected back to the infrared light sensor from the user&#39;s head. In some circumstances, such as when a user&#39;s hair is dark, the amount of reflected light from the user&#39;s head may be relatively small. Unless care is taken, proximity sensor signals will not be sufficiently accurate to properly deactivate a touch screen. 
     It would therefore be desirable to be able to provide improved proximity sensors for electronic devices. 
     SUMMARY 
     An electronic device may be provided with a display. A display cover layer such as a layer of transparent glass or plastic may cover the display. The display may display images for a user of the electronic device in a central active region of the display cover layer. The active region may be surrounded by an inactive display region. 
     In the inactive region, the underside of the display cover layer may be coated with an opaque masking layer such as a layer of black ink. An opening in the opaque masking layer may be filled with a material such as an infrared-transparent ink to form a window for a light-based proximity sensor. 
     A light-based proximity sensor may be mounted below the window. The proximity sensor may have a light source such as an infrared light-emitting diode that emits light. The proximity sensor may also have a detector that is configured to detect reflections of emitted light from the light-emitting diode that have reflected off of nearby external objects such as the head of a user. 
     Optical structures may be interposed between the proximity sensor and the window in the display cover layer. The optical structures may ensure that reflected signals are sufficiently strong without introducing undesirable noise from display cover layer reflections. 
     The optical structures may include a first portion such as a convex lens that is configured to collimate light from the light source. The collimated light may propagate along a vertical axis that serves as a surface normal to the display cover layer. The collimated light may produce relatively few reflections from the display cover glass that have the potential to lead to noise signals. 
     The optical structures may also include a second portion such as a prism structure or other light reflecting structure for deflecting light away from the propagation axis of the collimated light. The deflected light may be uncollimated. Use of uncollimated light in illuminating external objects may help increase reflected signal strength. The second portion of the optical structures may be configured so that the deflected light tends not to reflect into the detector to produce noise. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with proximity sensor structures in accordance with an embodiment of the present invention. 
         FIG. 2  is a side view of a portion of an electronic device showing where proximity sensor structures and a proximity sensor window for the proximity sensor structures may be formed in accordance with an embodiment of the present invention. 
         FIG. 3  is a side view of a proximity sensor structure in which optical structures are being used to collimate emitted light in accordance with an embodiment of the present invention. 
         FIG. 4  is a side view of a proximity sensor structure in which optical structures are being used to distribute light in an uncollimated pattern in accordance with an embodiment of the present invention. 
         FIG. 5  is a side view of a proximity sensor structure in which optical structures are being used to distribute a first portion of sensor light in an on-axis vertical collimated pattern while distributing a second portion of sensor light with an angular spread in an off-axis direction in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view of illustrative optical structures for distributing sensor light in both vertical collimated and angled uncollimated patterns in accordance with an embodiment of the present invention. 
         FIG. 7  is a top view of the illustrative optical structures of  FIG. 6  in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of a proximity sensor under a portion of a sensor window in an electronic device in a configuration in which the proximity sensor emitter has associated optical structures for distributing sensor light in both on-axis collimated and off-axis uncollimated patterns in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective view of the optical structures of  FIG. 8  and an associated proximity sensor emitter and detector in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of illustrative optical structures in which a reflecting structure for distributing emitted light in an uncollimated off-axis pattern has been formed from multiple protruding structures along one side of a convex lens in accordance with an embodiment of the present invention. 
         FIG. 11  is a top view of the illustrative optical structures of  FIG. 10  in accordance with an embodiment of the present invention. 
         FIG. 12  is a cross-sectional side view of illustrative proximity sensor optical structures that have first and second optical elements for distributing sensor light in both vertical collimated and angled uncollimated patterns in accordance with an embodiment of the present invention. 
         FIG. 13  is a cross-sectional side view of an illustrative optical configuration for a proximity sensor in which optical structures for distributing sensor light in both vertical collimated and angled uncollimated patterns are formed using overlapping first and second optical elements in accordance with an embodiment of the present invention. 
         FIG. 14  is a cross-sectional side view of an illustrative optical configuration for a proximity sensor in which optical structures for distributing sensor light in both vertical collimated and angled uncollimated patters are formed using a lens structure and diffractive optical element in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as device  10  of  FIG. 1  may be provided with proximity sensor components. The proximity sensor components may include light-based proximity sensor components that can be used to make light-based proximity sensor measurements. Proximity sensor data may be used in controlling the operation of device  10 . For example, proximity sensor data may be used in controlling touch sensor functions and may be used in controlling other device functions. Device  10  may monitor proximity sensor output during operation of a touch screen and other device features. If the proximity sensor output indicates that an external object such as a user&#39;s head is within close proximity to the device, touch sensor functionality may be momentarily deactivated to avoid unintended touch input from the external object. 
     Device  10  of  FIG. 1  may be a portable computer, tablet computer, computer monitor, handheld device, global positioning system equipment, gaming device, cellular telephone, portable computing equipment, or other electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. 
     Housing  12  may be formed using an unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     In some configurations, housing  12  may be formed using front and rear housing structures that are substantially planar. For example, the rear of device  10  may be formed from a planar housing structure such as a planar glass member, a planar plastic member, a planar metal structure, or other substantially planar structure. The edges (sidewalls) of housing  12  may be straight (vertical) or may be curved (e.g., housing  12  may be provided with sidewalls formed from rounded extensions of a rear planar housing wall). As shown in  FIG. 1 , the front of device  10  may include a planar display such as display  14  that is covered with a planar cover layer. The cover layer that covers the surface of display  14  may be formed from clear glass, clear plastic, or other transparent materials (e.g., materials that are transparent to visible light and that are generally transparent to infrared light). The cover layer that covers display  14  is sometimes referred to as a display cover layer, display cover glass, or plastic display cover layer. 
     Display  14  may, for example, be a touch screen that incorporates capacitive touch electrodes or a touch sensor formed using other types of touch technology (e.g., resistive touch, acoustic touch, force-sensor-based touch, etc.). Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) components, or other suitable image pixel structures. 
     Display  14  and the cover layer on display  14  may have an active region and an inactive region. Active region  22  of display  14  may lie within rectangular boundary  24 . Within active region  22 , display pixels such as liquid crystal display pixels or organic light-emitting diode display pixels may display images for a user of device  10 . Active display region  22  may be surrounded by an inactive region such as inactive region  26 . Inactive region  26  may have the shape of a rectangular ring surrounding active region  22  and rectangular boundary  24  (as an example). To prevent a user from viewing internal device structures under inactive region  26 , the underside of the cover layer for display  14  may be coated with an opaque masking layer in inactive region  26 . The opaque masking layer may be formed from a layer of ink (e.g., black or white ink or ink of other colors), a layer of plastic, or other suitable opaque masking material. 
     Device  10  may include input-output ports, buttons, sensors, status indicator lights, speakers, microphones, and other input-output components. As shown in  FIG. 1 , for example, device  10  may include one or more openings in inactive region  26  of display  14  to accommodate buttons such as button  16  and may include one or more openings such as speaker port opening  18  to accommodate audio components. 
     Device  10  may include one or more optical components. For example, device  10  may include a light sensor such as visible light sensor that makes measurements on the level of ambient light in the vicinity of device  10 . The optical components may also include a light-based proximity sensor. A proximity sensor of this type may emit light and may detect how much of the emitted light is reflected from external objects. Because more light tends to be reflected when external objects are in close proximity to the proximity sensor, the amount of reflected light that is detected by the proximity sensor may be used to determine whether or not external objects are located within the vicinity of the proximity sensor. 
     A proximity sensor may be mounted on the front or rear surface of device  10 , may be mounted on housing sidewalls, or may be mounted in other suitable device locations. With one illustrative arrangement, which is sometimes described herein as an example, a proximity sensor may be located under a portion of inactive region  26 . The proximity sensor may, for example, be located under region  20  of inactive region  26 . Region  20  may be formed from an opening or other window in inactive region  26 . 
     The proximity sensor may include an infrared light emitter and an infrared light detector. A infrared-transparent material such as “infrared ink” that tends to block visible light while allowing infrared light to pass may be used to cover region  20  (i.e., a proximity sensor window may be formed in region  20  by creating an opening in an opaque masking layer in region  26  and by filling the opening with a layer of infrared-transparent ink). 
     A cross-sectional side view of device  10  in the vicinity of proximity sensor window  20  is shown in  FIG. 2 . As shown in  FIG. 2 , display  14  of device  10  may include display structures that generate images such as display module  30 . Display module  30  may be an organic light-emitting-diode display module, a liquid crystal display module, or other display structures for generating visible images for a user of device  10 . Display module  30  may be mounted within housing  12  (e.g., on the front surface of device  10 ). Display module  30  may, if desired, include a touch sensor array such as a capacitive touch sensor array or a touch sensor formed using other touch technologies. 
     Display module  30  may be covered with a cover layer such as cover layer  48 . Cover layer  48  may be formed from a clear layer of plastic, a clear (transparent) glass layer, or other suitable transparent layer. The underside of cover layer  48  in inactive region  26  may be provided with an opaque masking layer such as opaque masking layer  32 . Opaque masking layer  32  may be formed from a material that is opaque at visible wavelengths such as black ink, black plastic, ink or plastic with other colors (blue, silver, white, etc.), or other suitable opaque material. Opaque masking layer  32  may help block interior device components such as proximity sensor  36  from view through layer  48  by a user of device  10 . In active region  22  of display  14 , cover layer  48  may be free of opaque masking layer material. 
     Proximity sensor window  20  may be formed by creating an opening in opaque masking layer  32  and filling the opening with a layer of material such as infrared ink  34  that is able to block at least some visible light while allowing infrared light to be transmitted. Other types of schemes may be used for mounting proximity sensor  36  within housing  12  if desired. The use of an infrared-light-compatible proximity sensor window in opaque masking layer  32  on the underside of a transparent planar member such as display cover layer  48  is merely illustrative. 
     Proximity sensor  36  may include a light source such as light source  38  and a light detector such as light detector  40 . Light source  38  may be, for example, an infrared light-emitting diode that emits light  42 . Light  42  may pass through proximity sensor window  20  and the material of cover layer  48 . Upon striking the head of a user of device  10  or other external object  46 , light  42  may be reflected off of the object, as shown by reflected light  44  in  FIG. 2 . 
     Reflected light  44  may be detected using a light detector in proximity sensor  36  such as light detector  40 . Light detector  40  may be, for example, a silicon photosensor. By measuring the magnitude of the reflected light signal, proximity sensor  36  may be used to determine whether external object  46  is in the proximity of device  10 . For example, the magnitude of reflected light  44  may be compared to a threshold level or may be otherwise processed to ascertain whether external object  46  is sufficiently close to display  14  to warrant actions such as temporary deactivation of the touch sensor functions of display  14 . 
     Light source  38  and light detector  40  may be housed in a common package, may be formed from separately packaged devices that are mounted to a common substrate (e.g., a printed circuit substrate formed from a rigid printed circuit board material such as fiberglass-filled epoxy or a flexible printed circuit substrate material such as a sheet of polyimide or other flexible polymer), or may otherwise be mounted within housing  12 . 
     The pattern in which light  42  is emitted from device  10  can affect the performance of sensor  36 . Illustrative proximity sensor configurations for device  10  are shown in  FIGS. 3, 4, and 5 . 
     In a configuration of the type shown in  FIG. 3 , light may be emitted in a collimated pattern. As shown in  FIG. 3 , light source  38  may emit light  42 A upwards along vertical axis  52  (i.e., an axis that serves as a surface normal for planar display cover layer  48  of  FIG. 2 ). Axis  52  extends parallel to vertical (surface normal) dimension Z. Light  42 A may be emitted from light source  38  with an angular spread that is dictated by the type of light-emitting diode or other component that is used for implementing light source  38 . As an example, light  42 A (e.g., light  42 A of  FIGS. 3, 4, and 5 ) may have an angular spread of about 0-40° as the light exits light source  38 . 
     Cover layer  48  (not shown in  FIGS. 3, 4, and 5 ) may lie in the x-y plane. A lens or other optical structures  50  may be used to reduce the angular spread of light  42 A. For example, a lens or other optical structures  50  may collimate light  42 A or may otherwise refract or direct light  42 A to produce patterned light  42 B. Patterned light  42 B may be collimated light that propagates substantially parallel to axis  52  and is characterized by a uniform lateral dimension D. Axis  52 , which may sometimes be referred to as a vertical axis, may form a surface normal for planar display cover layer  48  and may represent the direction of propagation (propagation axis) of collimated light  42 B. The angular deviation A of the most divergent light rays in collimated light  42 B relative to axis  52  and vertical dimension may be relatively small (i.e., A may be less than 10°, less than 4°, or less than 2°). 
     The use of collimated light in detecting the presence of external object  46  may help avoid undesirable detector noise that might otherwise arise due to reflections of light  42 B from cover layer  48  into detector  40  (e.g., angled-light reflections from the uppermost glass-air or plastic-air interface associated  48 . The exclusive use of collimated light may, however, result in relatively low signal strength for the reflected light signal, particularly when light  42 B strikes a dark external object. 
     In a configuration of the type shown in  FIG. 4 , light may be emitted vertically in an uncollimated (angularly spreading) pattern. As shown in  FIG. 4 , light source  38  may emit light  42 A upwards along vertical axis  52 , parallel to vertical dimension Z. A lens or other optical structures  50  may be used to direct light  42 A so that light  42 A is emitted from device  10  as patterned light  42 B. The most divergent light rays in patterned light  42 B of  FIG. 4  may be characterized by an angular deviation A relative to axis  52  and vertical dimension Z that is relatively large compared to that of collimated light  42 B of  FIG. 3  (e.g., greater than 10°, greater than 25°, or greater than 40°). 
     The use of diverging light  42 B such as patterned light  42 B in the example of  FIG. 4  in detecting the presence of external object  46  may help improve the amount of reflected light that is detected by detector  40 , but may give rise to undesirable scattered light noise as the divergent light rays are reflected by cover layer  48  (e.g., the uppermost glass-air or plastic-air interface in layer  48 ) and enter detector  40 . 
     If desired, a configuration of the type shown in  FIG. 5  may be used in device  10  to obtain the benefits of both collimated and uncollimated designs. As shown in  FIG. 5 , a proximity sensor light source such as light source  38  may be used to emit light  42 A. Light  42 A may pass through optical structures  50 . Optical structures  50  may include at least first optical structures  50 A (e.g., light deflecting structures such as a prism, mirror, or other light reflector) and second optical structures  50 B (e.g., light collimating structures or other light focusing or light refracting structures such as a convex lens). 
     Examples of optical structures that may be included in optical structures  50  include simple and compound lenses, prisms, mirrors, other light bending and/or light reflecting structures, gratings and other patterned structures for diffracting light, and other optical components. If desired, optical structures  50  may be used in reflecting and refracting light  42 A and may therefore sometimes be referred to as catadioptric optical structures or a catadioptric optical system. In general, any suitable structures for reflecting and/or refracting and/or diffracting light may be used in forming optical structures  50 . 
     First optical structures  50 A and second optical structures  50 B are shown as being formed at laterally adjacent locations in the X-Y plane of  FIG. 5 . This is merely illustrative. Optical structures  50 A and  50 B may be implemented using optical structures at any suitable locations in device  10 . 
     Optical structures  50 B may reflect and/or refract a portion of light  42 A to form collimated light  42 B- 1 . As described in connection with light  42 B of  FIG. 3 , for example, optical structures  50 B may produce light  42 B- 1  that propagates in vertical direction Z along vertical propagation axis  52 . If desired, light  42 B- 1  may be characterized by a relatively small angular spread A away from vertical dimension Z (and propagation axis  52  for collimated light  42 B- 1 ), so that light  42 B- 1  can be used in providing proximity sensing functions without introducing excessive noise due to reflections of light from cover layer  48  towards sensor  40 . 
     As optical structures  50 B are being used to produce collimated light  42 B- 1 , optical structures  50 A may be used to reflect and/or refract a portion of light  42 A to produce uncollimated light  42 B- 2 . Uncollimated light  42 B- 2  may propagate in an angled propagation direction defined by propagation axis  54 . Axis  54  may be oriented at a non-zero angle such as angle C with respect to vertical dimension Z and axis  52 . Because light  42 B- 2  is not collimated (in this example), light  42 B- 2  will be characterized by a non-zero angular spread away from propagation axis  54 . In particular, the most divergent light rays in light  42 B- 2  may be characterized by an angular deviation B relative to axis  54  that is relatively large. The magnitude of angle B may be, for example, greater than 5°, greater than 10°, greater than 25°, or greater than 40° (as examples). The presence of uncollimated light  42 B- 2  may help to increase the magnitude of reflected light  44  that is received by light detector  40  in proximity sensor  36 . The non-zero angle C of propagation axis  54  with respect to vertical dimension Z and axis  52  may be configured to reduce or eliminate the reception of undesired reflections from cover layer  48  by detector  40 . 
     A cross-sectional side view of an illustrative configuration that may be used for optical structures  50  is shown in  FIG. 6 . As shown in  FIG. 6 , optical structures  50  may include lens structure  50 B for refracting light  42 A and thereby forming collimated light  42 B- 1 . Collimated light  42 B- 1  may propagate parallel to axis  52 . Optical structures  50  may also include prism structure  50 A for reflecting light  42 A and thereby forming reflected uncollimated light  42 B- 2  that propagates along propagation axis  54 . 
     In the example of  FIG. 6 , prism structure  50 A is formed from a relatively small edge portion of structures  50  and lens structure  50 B is formed from a larger convex lens shaped portion in the middle of structures  50 . Structures  50 A and  50 B may, as an example, be formed from a common molded plastic part. Other arrangements may be used, if desired. For example, structures  50 A and structures  50 B may consume equal areas or structures  50 A may be larger than structures  50 B. Structures  50 A and structures  50 B may be formed from independent optical elements or may be formed from parts of a common optical structure, structure  50 A may be formed from a mirror structure that includes metal, a reflective thin-film stack (e.g., a dielectric stack of layers of material with different indices of refraction), or other reflective materials. Structures  50 A and  50 B may be formed from plastic, glass, ceramic, other materials, or combinations of these materials. 
     With a configuration of the type shown in  FIG. 6 , the location at which light  42 A strikes structures  50  affects how light  42 A is routed by optical structures  50 . Light rays  42 A such as light ray  42 A″ that are located at a radial distance R 1  from longitudinal axis  52  of optical structures  50  may, for example, strike portion  50 B of structures  50  and may, following refraction by the material of portion  50 B, become part of collimated light  42 B- 1 . Light rays  42 A such as light ray  42 A′ that are located at a larger radial distance such as radial distance R 2  from longitudinal axis  52  may, strike portion  50 A of structures  50  and may, following reflection by the material of portion  50 A, become part of uncollimated light  42 B- 1 . 
       FIG. 7  is a top view of optical structures  50  of  FIG. 6 . As shown in  FIG. 7 , prism structures  50 A may be located on one side of structures  50 B (as an example). In this type of arrangement structures  50 B may be rotationally symmetric about rotational (vertical) axis  52  while overall, structures  50  are rotationally asymmetric about axis  52  (i.e., the portions of structures  50  that are used in deflecting light along path  54  and that are used in collimating refracting light are not, taken together, rotationally symmetric around axis  52 ). If desired, a configuration may be used for structures  50  in which structures  50 A are incorporated into structures  50  in other locations. For example, some or all of structures  50 A may be placed in the locations shown by dashed lines  50 A′ (as examples). 
       FIG. 8  is a cross-sectional side view of device  10  showing how optical structures such as optical structures  50  of  FIGS. 6 and 7  may be used to direct emitted light  42 A from light source  38  through a proximity sensor window such as a window formed from infrared-transparent ink  34  and cover layer  48 . Light  42 A that strikes structures  50 B will be collimated by structures  50 B and may exit structures  50 B and cover layer  48  as collimated light  42 B- 1 . Light  42 A that strikes structures  50 A will be reflected by structures  50 A and may exit structures  50 A and cover layer  48  as uncollimated light  42 B- 2 . 
     Structures  50 A may be configured to minimize light reflection into lens  60  and associated light detector  40  of proximity detector  36 . The configuration of structures  50 A may produce certain rays of reflected light such as light ray  66  that have the potential to reach lens  60  and thereby be detected by light detector  40 . However, as illustrated in  FIG. 8 , these light rays (e.g., light ray  66  of  FIG. 8 ) reflect from the air-glass (or air-plastic) interfaces in cover layer  48  three times (at locations  68 ,  70 , and  72 ). Due to these multiple reflections, the intensity of light ray  66  will generally be reduced to a negligible level. 
     Other light rays such as rays  62  of  FIG. 8  may have the potential to reach the vicinity of lens  60  with only one cover layer reflection (e.g., a reflection at location  64 ). Because only a single reflection is involved in cover layer  48  for light rays  62 , the intensity of light rays  62  will tend to be larger than the intensity of light ray  66 . Nevertheless, due to the locations of optical structures  50  and  60  and the direction of propagation of light rays  62  upon exiting prism structures  50 A and cover layer  48 , light rays  62  will not be collected by the lens formed from optical structures  60 . As a result, light rays  62  will not be focused onto light detector  40  and will not be detected by light detector  60 . Light rays  62  will therefore not contribute to reflected light noise in proximity sensor  36 . If desired, undesired reflections into detector  40  can be further reduced by incorporating antireflection coatings into layer  48  (e.g., on the outer surface of layer  48 ). In configurations in which antireflection coatings are omitted (e.g., to minimize cost, to improve device aesthetics, and/or to avoid challenges associated with implementing an antireflection structure that is effective over a wide range of angles), the use of structures that direct light rays  62  away from light detector  40  may be helpful in minimizing undesired reflected light noise. 
     By configuring optical structures  50  so that a portion of light  42 A is collimated by structures  50 B and serves as collimated light  42 B- 1 , the potential for undesired light reflections from cover layer  48  that could lead to noise at detector  40  may be minimized. By ensuring that a fraction of light  42 A is spread out in an uncollimated fashion after exiting structures  50 A and cover layer  48  may help ensure that reflected light  44  from external object  46  is sufficiently strong. During proximity sensor operations, light  44  may be focused onto light detector  40  and used to determine whether or not external object  46  is in proximity to device  10 . Structures  50 A may be configured so that the angle at which light  42 B- 2  exits cover layer  48  (i.e., propagation direction  54 ) is at a non-zero angle with respect to vertical dimension Z. The magnitude of the non-zero angle may be selected to cause light reflected from cover layer  48  to experience multiple reflections that diminish its intensity or to avoid striking lens  60  entirely and to thereby avoid being detected by light detector  40 . 
       FIG. 9  is a perspective view of optical structures  50  and  60  and proximity sensor  36  of  FIG. 8 . Optical structures  50  and  60  may be formed from molded plastic, glass, or other optical materials. Reflective optical structures may be formed using reflective materials such as metal, using dielectric structures such as prism structures that reflect light when the light reaches a solid-air interface, using reflective structures formed using thin-film stacks, or other reflective structures. 
     If desired, structures  50 A may be formed from multiple protrusions  74  as shown in  FIG. 10 . The protruding portions of optical structures  50  that form illustrative optical structures  50 A of  FIG. 10  may, for example, be protrusions of glass or plastic (e.g., Fresnel structures) that are integral portions of structures  50  and that collectively create an optical structure for reflecting a portion of light  42 A in a non-vertical direction such as direction  54  of  FIG. 8  while spreading the reflected light in an uncollimated pattern. 
       FIG. 11  is a top view of optical structures  50  of the type shown in  FIG. 10 . If desired, optical structures  50 A of  FIG. 11  may be located elsewhere among structures  50 , as described in connection with locations  50 A′ of  FIG. 7 . 
     As shown in  FIG. 12 , optical structures  50  may be formed from prism structures  50 A or other light reflecting (or refracting) light deflection structures that are separate from optical structures  50 B. Separate optical elements for forming structures  50 A and  50 B may be mounted in a unitary package or may be mounted using separate mounting structures. Optical elements  50 A and  50 B may both be formed from glass, may both be formed from plastic, or may both be formed from other suitable materials. If desired, optical elements  50 A and  50 B may be formed from different materials. For example, optical element  50 A may be formed from a glass prism and optical element  50 B may be formed from a molded plastic lens. As another example, optical element  50 A may be formed from a reflective metal surface or a reflector constructed from a thin-film stack and optical element  50 B may be formed from a molded plastic lens or a glass lens. 
     In the illustrative arrangement of  FIG. 12 , optical structures  50 B and optical structures  50 A have been formed from separate structures that each separately received light  42 A directly from light source  38 . If desired, structures  50 A and  50 B may optically overlap so that light passes through one of the structures and then the other in series. This type of arrangement is shown in  FIG. 13 . As shown in  FIG. 13 , light  42 A may pass through edge portion  80  of optical structures  50 B before passing through optical structures  50 A. Upon reaching structures  50 A, light  42 A may be deflected along path  54  to become uncollimated light  42 B- 2 . Light  42 A that strikes other portions of structures  50 B may be collimated by structures  50 B to form collimated light  42 B- 1 . 
     If desired, optical structures  50  may include structures  50 B that do not completely collimate light  42 A. For example, optical structures  50  may have structures such as structures  50 A that deflect uncollimated light along a path such as path  54  and may have structures  50 B that gather light into a less divergent (but potentially still uncollimated) pattern of light. In this type of arrangement, optical structures  50 A may deflect light in a path that avoids reflecting light from cover layer  48  into sensor  40  while optical structures  50 B may direct light along a propagation direction such as vertical axis  52  towards external object  46  without excessive light divergence (e.g., with an angular spread characterized by an angle A relative to axis  52  that is less than 30°). 
       FIG. 14  is a cross-sectional side view of an illustrative optical configuration for a proximity sensor in which optical structures  50  include a diffractive optical element. Optical structures  50  may, for example, include a lens or other optical structures  50 B that collimate light  42 A to produce light  42 B- 1  and may include a grating or other diffractive optical element such as optical structures  50 A. In the example of  FIG. 14 , optical structures  50 A and optical structures  50 B have been formed from separate structures that each separately received light  42 A directly from light source  38 . If desired, structures  50 A and  50 B may optically overlap so that light passes through one of the structures and then the other in series, as described in connection with  FIG. 13 . 
     Diffractive optical element  50 A may include a grating or optical slit that is formed from patterned metal structures, diffractive structures that are formed by modulating the index of refraction of dielectric materials, gratings, slits, and other diffracting structures formed from opaque substances such as ink, plastic, thin-film layers of dielectric and metal, or any other structures capable of diffracting light  42 A and thereby deflecting the light from emitter  38  so that resulting deflected light  42 B- 1  travels along a desired path. As shown in  FIG. 14 , light  42 A that has passed through diffractive optical structures  50 A may, for example, be deflected to form uncollimated deflected light  42 B- 2  that travels in a direction centered along path  54 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20110923
Publication Date: 20160614
Grant Date: 20160614
Priority Date: 20110923
Inventors: RUH RICHARD
Assignee: APPLE INC
CPC Classifications: [{"code": "G01S17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/4814", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S7/4814", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01S17/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S17/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01S7/4814", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 47080788