Abstract:
Portable electronic devices are provided. A device may include cover glass with a light mask. The light mask may be microperforated to allow light to pass through the light mask. The microperforations may allow light to pass through the light mask. The devices may include sensors and light emitters that receive and transmit light through the microperforations. The devices may include a variable cantilever spring as part of a button assembly. The spring may be flattened against itself without exceeding its elastic limit. The devices may include display modules. The display module may include structures that block light from leaking out of the module. The structures may include opaque tapes, opaque enclosures for the display module, and other suitable structures.

Description:
BACKGROUND 
       [0001]    This relates generally to electronic devices and, more particularly, to portable electronic devices. 
         [0002]    Electronic devices such as portable electronic devices are becoming increasingly popular. Examples of portable devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. Popular portable electronic devices that are somewhat larger than traditional handheld electronic devices include laptop computers and tablet computers. 
         [0003]    An electronic device may include one or more sensors. The sensors may be used to sense information about the environment around the electronic device such an ambient light level and the proximity of nearby objects. The electronic device may include one or more apertures that pass radiation between the sensors and the external environment. The apertures may not be aesthetically pleasing and may divert attention away from other aesthetically pleasing features of the electronic device. It would therefore be desirable to provide electronic devices that have improved sensor apertures. 
         [0004]    An electronic device may include a housing and a display module mounted in the housing. The display module may emit light through a display opening in the housing. With conventional display modules, light may also escape into the housing from the sides and rear of the display module. The light that escapes into the housing can then escape through cracks or joints in the housing which is aesthetically undesirable. It would therefore be desirable to provide display modules for electronic devices that minimize light leakage. 
         [0005]    Electronic devices may sometimes include a compression spring as part of a button mechanism. Conventional button springs can become deformed and non-functional if they are fully compressed. It would therefore be desirable to provide springs for button mechanisms in an electronic device that can be more fully compressed without deforming. 
       SUMMARY 
       [0006]    Portable electronic devices are provided. The electronic devices may be hybrid devices that combine the functionality of multiple devices. An example of a hybrid electronic device is a cellular telephone that includes media player functionality. 
         [0007]    An electronic device may include a display and a transparent cover that covers the display. The transparent cover may be formed from cover glass and may extend beyond the borders of the display and, if desired, may cover a majority of one or more sides of the electronic device. For example, the cover glass may extend almost entirely across the front face of the electronic device. With one suitable arrangement, the electronic device may include a mask behind or in front of portions of the cover glass to obscure internal components in the electronic device from view. Generally, the mask need not extend across the display. However, if desired, the mask may overlap the edges of the display. The cover glass and mask may have portions defining holes. As an example, the holes may include a hole for a button mechanism (e.g., a menu button hole) and a hole for a speaker (e.g., a port for transmitting sound through the cover glass). 
         [0008]    A mask for cover glass in an electronic device may include microperforations. The microperforations may allow light and other radiation to pass through the mask and cover glass. With this type of arrangement, the electronic device may include sensors underneath the cover glass that can transmit and receive radiation through the cover glass. The microperforated mask may allow radiation to pass through the mask while simultaneously obscuring the sensors from a user&#39;s view. In general, the electronic device may include any desired type of sensor such as a proximity sensor, an ambient light sensor, an orientation sensor, etc. With one suitable arrangement, the mask may be formed from a relatively thin layer of deposited material and, as an example, the microperforations may be formed using a laser to selectively etch away portions of the mask. 
         [0009]    An electronic device may include a display with structures that reduce light leakage from the display. The display, which is sometimes referred to as a display module, may include a plurality of layers held together in a chassis. As an example, the display may include structures that reduce light leakage from the display such as one or more strips of opaque tape. Strips of opaque tape may be applied to the exterior surface of the display module (e.g., to the exterior surface of a chassis for the display) to reduce light leakage from the display (e.g., to reduce the amount of light that escapes into the interior of the electronic device). If desired, strips of opaque tape may be placed in the interior of the display module (e.g., applied to an interior surface of the chassis) to reduce light leakage from the display. 
         [0010]    An electronic device may include one or more compression springs. The compression springs may be a part of a button mechanism in the electronic device, as an example. With one suitable arrangement, a compression spring may be formed with a curved cantilever shape so that the spring does not plastically deform even if the spring is completely compressed. With another suitable arrangement, a compression spring may be formed with a variable cantilever shape and may incorporate a self-strengthening tip portion that increases the uncompressed height of the spring following a complete compression of the spring. 
         [0011]    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 
         [0012]      FIG. 1  is a perspective view of an illustrative portable electronic device in accordance with an embodiment of the present invention. 
           [0013]      FIG. 2  is a schematic diagram of an illustrative portable electronic device in accordance with an embodiment of the present invention. 
           [0014]      FIG. 3  is a cross-sectional side view of a conventional sensor mounted beneath a cover glass. 
           [0015]      FIG. 4  is a cross-sectional side view of an illustrative cover glass in a portable electronic device that may have a light mask showing how the light mask may be perforated to allow light to pass through portions of the light mask in accordance with an embodiment of the present invention. 
           [0016]      FIG. 5  is a cross-sectional side view of an illustrative sensor and cover glass with a light mask in a portable electronic device that shows how the light mask may be perforated to allow light to pass through the cover glass to the sensor in accordance with an embodiment of the present invention. 
           [0017]      FIG. 6  is a front view of an illustrative cover glass with a light mask that may have microperforations to allow light to pass through the cover glass to one or more sensors that may be mounted beneath the cover glass in accordance with an embodiment of the present invention. 
           [0018]      FIG. 7  is a front view of an illustrative light mask that may be perforated to allow light to pass through the light mask in accordance with an embodiment of the present invention. 
           [0019]      FIG. 8  is a rear view of an illustrative display module that may include structures to reduce light leakage from the display module in accordance with an embodiment of the present invention. 
           [0020]      FIG. 9  is a cross-sectional end view of an illustrative display module that may include multiple layers and a chassis that holds the layers together in accordance with an embodiment of the present invention. 
           [0021]      FIG. 10  is a cross-sectional side view of a glass panel layer that may be part of the illustrative display module of  FIG. 9  in accordance with an embodiment of the present invention. 
           [0022]      FIG. 11  is a cross-sectional side view of an illustrative display module that may be mounted to a mounting structure in an electronic device with double-sided tape in accordance with an embodiment of the present invention. 
           [0023]      FIG. 12  is a side view of a conventional display module with clear tape that allows light to escape from the display module. 
           [0024]      FIG. 13  is a rear view of an illustrative display module with opaque tape that helps to hold the layers of the display module together and that blocks errant light to prevent the light from escaping from the display module in accordance with an embodiment of the present invention. 
           [0025]      FIG. 14  is a perspective view of an illustrative compression spring that may be a part of a button mechanism in an electronic device in accordance with an embodiment of the present invention. 
           [0026]      FIG. 15  is a side view of the illustrative compression spring of  FIG. 14  that shows various dimensions of the compression spring in accordance with an embodiment of the present invention. 
           [0027]      FIG. 16  is a bottom view of the illustrative compression spring of  FIG. 14  showing a portion of the compression spring that may be used as an attachment point for mounting the compression spring in the electronic device in accordance with an embodiment of the present invention. 
           [0028]      FIG. 17  is a top view of the illustrative compression spring of  FIG. 14  that shows various dimensions of the compression spring in accordance with an embodiment of the present invention. 
           [0029]      FIG. 18  is a cross-sectional side view of the illustrative compression spring of  FIG. 14  mounted in an illustrative electronic device in accordance with an embodiment of the present invention. 
           [0030]      FIG. 19  is a cross-sectional side view of an illustrative electronic device with a button mechanism which includes a pair of compression springs in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    The present invention relates to electronic devices and components in electronic devices. The electronic devices may be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. 
         [0032]    With one suitable arrangement, the portable electronic devices may be wireless electronic devices. The wireless electronic devices may be, for example, handheld wireless devices such as cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), global positioning system (GPS) devices, and handheld gaming devices. The wireless electronic devices may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid portable electronic devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a portable device that receives email, supports mobile telephone calls, has media player functionality, and supports web browsing. These are merely illustrative examples. 
         [0033]    An illustrative electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . User device  10  may be any suitable electronic device such as a portable or handheld electronic device. Device  10  of  FIG. 1  may be, for example, a handheld electronic device that supports 2G and/or 3G cellular telephone and data functions, global positioning system capabilities or other satellite navigation capabilities, and local wireless communications capabilities (e.g., IEEE 802.11 and Bluetooth®) and that supports handheld computing device functions such as internet browsing, email and calendar functions, games, media player functionality, etc. 
         [0034]    Device  10  may have housing  12  and display  16 . Housing  12 , which is sometimes referred to as a case, may be formed from any suitable material including, plastic, glass, ceramics, metal, or other suitable materials, or a combination of these and other materials. 
         [0035]    Display  16  may be a liquid crystal display (LCD), a thin film transistor liquid crystal display (TFT-LCD), an organic light-emitting diode (OLED) display, or any other suitable display. The outermost surface of display  16  may be formed from one or more plastic or glass layers. If desired, touch screen functionality may be integrated into display  16  or may be provided using a separate touch pad device. With one suitable arrangement, display  16  may include structures that reduce light leakage from display  16  (e.g., structures that help to prevent light from escaping from display  16  to the interior of device  10 ). 
         [0036]    Display screen  16  (e.g., a touch-screen) is merely one example of an input-output device that may be used with electronic device  10 . If desired, electronic device  10  may have other input-output devices. For example, electronic device  10  may have user input control devices such as button  19 , and input-output components such as port  20  and one or more input-output jacks (e.g., for audio and/or video). Button  19  may be, for example, a menu button. Port  20  may contain a 30-pin data and power connector (as an example). Openings  22  and  24  may, if desired, form speaker and microphone ports. Speaker port  22  may be used when operating device  10  in speakerphone mode. Opening  23  may also form a speaker port. For example, speaker port  23  may serve as a telephone receiver that is placed adjacent to a user&#39;s ear during operation. In the example of  FIG. 1 , display screen  16  is shown as being mounted on the front face of handheld electronic device  10 , but display screen  16  may, if desired, be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
         [0037]    If desired, a button mechanism in device  10  such as button  19  may include a compression spring. The spring may be, as one example, a variable cantilever spring that can be fully compressed without permanently deforming (e.g., without undergoing plastic deformation). 
         [0038]    A user of electronic device  10  may supply input commands using user input interface devices such as button  19  and touch screen  16 . Suitable user input interface devices for electronic device  10  include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a microphone for supplying voice commands, or any other suitable interface for controlling device  10 . Buttons such as button  19  and other user input interface devices may be formed on any suitable portion of device  10 . 
         [0039]    If desired, some or all of the input commands for device  10  may be received using accessories. This type of arrangement may help to reduce the size of the device  10  by reducing or even eliminating the number of control interfaces (e.g., buttons, sliders, etc.) located on the device  10 . With one suitable arrangement, the device  10  may connect with a headset through a connector such as connector  20  or an audio connector (e.g., a tip, ring, and sleeve female audio connector) and may receive control commands such as play, pause, stop, fast forward, skip forward, rewind, skip back, volume up, volume down, mute, and other control commands from the headset. In this arrangement, a headset may include speakers and a control unit that generates command signals that can be interpreted by the device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth® remote control, etc.). 
         [0040]    Device  10  may include cover  54 . As shown in  FIG. 1 , cover  54  may extend over a majority of the front surface of device  10 . Cover  54  may be formed from transparent glass or other suitable materials. Cover  54  may surround display  16  or may cover and surround display  16 , if desired. As one example, cover  54  may be opaque and may obscure the internal components (except for display  16 ) mounted inside device  10 . If desired, cover  54  may be somewhat or completely transparent so that a user can view the internal components mounted inside device  10 . With one suitable arrangement, cover  54  may be formed from a transparent member such as glass coated on at least one side with an opaque material such as paint or ink. For example, cover  54  may be formed from a sheet of glass that covers the front surface of device  10  and from a layer of black paint on the underside of the sheet of glass. If desired, cover  54  (e.g., a sheet of glass) may extend over display  16  and the periphery of display  16  while the layer of black paint may extend over the periphery of display  16  but not over display  16 . In general, cover  54  may include glass and one or more layers of paint or other structure in any suitable shade and pattern or combination thereof. Cover  54  may sometimes be referred to as cover glass. With one suitable arrangement, display  16  may have an active image area (e.g., the outlined portion of display  16  in  FIG. 1 ) and an inactive peripheral region (e.g., the regions on the front face of device  10  beyond the outline portion of display  16  in  FIG. 1 ). As one example, cover  54  may include an opaque layer that covers the inactive peripheral region of display  16 . If desired, cover  54  and display  16  may be integrated together (e.g., cover  54  may be incorporated into display  16 ). 
         [0041]    Device  10  may contain sensors for monitoring the environment around device  10 . For example, device  10  may include sensors such as acoustic sensors, accelerometers, thermometers, altimeters and/or barometers, proximity sensors, ambient light sensors, etc. If desired, device  10  may include a proximity sensor that uses an emitter (e.g., an infrared LED or a radiation source that operates in another frequency) and a receiver or detector (e.g., an infrared receiver or a radiation detector that operates in another frequency) for detecting radiation. The proximity sensor may determine the distance to a nearby object by emitting radiation through the emitter and detecting radiation that has reflected off of the object, as an example. With one suitable arrangement, one or more sensors in device  10  may be located underneath cover  54 . For example, as shown in  FIG. 1  device  10  may include one or more sensors beneath cover  54  at the location of outline  52 . In general, sensors in device  10  may be located at any suitable location (e.g., in the inactive peripheral region of display  16 ). 
         [0042]    With one suitable arrangement, the portions of cover  54  above sensors in device  10  may be transparent or semi-transparent to radiation (i.e., visible and/or infrared light). As one example, cover  54  may be formed from transparent glass that has an opaque coating that does not extend over the sensors in device  10  and that has an infrared coating that does extend over the sensors. The infrared coating may have an appearance similar to the opaque coating in the visible spectrum (blocking visible light) but may be transparent to infrared radiation. With another suitable arrangement, the opaque coating over cover  54  may extend over some or all of the sensors in device  10  and may include a plurality of microperforations. For example, cover  54  may include a black mask (e.g., a black paint) with a plurality of microperforations. The microperforations in the black mask may be located between sensors in device  10  and the external environment such that radiation can pass between the sensors and the external environment. With one suitable arrangement, the opaque coating on cover  54  may be formed from a thin layer of metal deposited onto the glass of cover  54  using a physical vapor deposition process. The microperforations may be formed by etching away selected portions of the deposited metal layer using a laser, using photolithographic patterning techniques, etc. 
         [0043]    A schematic diagram of an embodiment of an illustrative portable electronic device such as a handheld electronic device is shown in  FIG. 2 . Portable device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a laptop computer, a tablet computer, an ultraportable computer, a hybrid device that includes the functionality of some or all of these devices, or any other suitable portable electronic device. 
         [0044]    As shown in  FIG. 2 , device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
         [0045]    Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, processing circuitry  36  and storage  34  are used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, navigation functions, map functions, operating system functions, power management functions, etc. 
         [0046]    Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16 , button  19 , microphone port  24 , speaker port  22 , and dock connector port  20  are examples of input-output devices  38 . In general, input-output devices  38  may include any suitable components for receiving input and/or providing output from device  10 . For example, input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, cameras, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . 
         [0047]    Input-output device  38  may include sensors  41  such as proximity sensors, ambient light sensors, orientation sensors, proximity sensors, and any other suitable sensors. 
         [0048]    Display and audio devices  42  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
         [0049]    Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
         [0050]    Device  10  can communicate with external devices such as accessories  46 , computing equipment  48 , and wireless network  49 , as shown by paths  50  and  51 . Paths  50  may include wired and wireless paths. Path  51  may be a wireless path. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content), a peripheral such as a wireless printer or camera, etc. 
         [0051]    Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another portable electronic device  10 ), or any other suitable computing equipment. 
         [0052]    Wireless network  49  may include any suitable network equipment, such as cellular telephone base stations, cellular towers, wireless data networks, computers associated with wireless networks, etc. 
         [0053]    A conventional arrangement for mounting a sensor beneath cover glass in a cellular telephone is shown in  FIG. 3 . As shown in  FIG. 3 , cellular telephone  200  includes cover glass  202 . Cover glass  202  includes black paint  204  that serves as an opaque backing to cover glass  202 . Infrared light sensor  206  is located underneath the cover glass  202 . Black paint  204  does not extend between sensor  206  and cover glass  202 . Instead, infrared ink  208  is placed between sensor  206  and cover glass  202  to allow infrared radiation to pass between sensor  206  and the external environment. Typically, infrared ink  208  has an appearance that is similar to black paint  204  in the visible spectrum. Because convention infrared ink  208  has a nearly black appearance, it is difficult to maintain a uniform aesthetic appearance for conventional devices such as device  200  when the backing is not black in appearance. 
         [0054]    In contrast, device  10  of  FIG. 1  may incorporate a cover  54  that includes a backing that is not necessarily black in appearance. In general, the backing to cover  54  may be any suitable color and may include combinations of colors and/or patterns. With one suitable arrangement, the backing to cover  54  may have a silver color and may be metallic in appearance. In this example, the backing to cover  54  may be formed from using a physical vapor deposition process to deposit metallic material onto cover  54  (e.g., to deposit a thin metal layer onto cover glass  54 ). The backing to cover  54  may or may not be opaque. Opaque backings may be used to obscure internal components in device  10  from a user&#39;s view and transparent or semi-transparent backings may be used to showcase some or all of the internal components in device  10 , if desired. In addition, because the backing to cover  54  may not rely upon infrared ink to obscure internal components such as sensors, the sensors in device  10  may be able to effectively transmit and receive radiation in the visible light spectrum. 
         [0055]    As shown in  FIG. 4 , device  10  may include an opaque backing  56  that extends substantially over an entire surface of cover  54 . Backing layer  56  may include microperforations (e.g., relatively small holes) in region  58  in order to allow radiation (e.g., visible light and infrared light) to pass through the backing  56 . With one suitable arrangement, cover  54  may be formed from transparent glass and backing  56  may be an opaque material such as paint, a metallic layer, ink, etc. 
         [0056]    In general, microperforations may refer to relatively small holes that are substantially invisible while still transmitting a certain degree of light. The microperforations may be essentially invisible to a user but may allow enough light to pass through. As one example, when microperforations are formed in an opaque material, the microperforations may be invisible (e.g., the opaque material may have a relatively seamless appearance) unless a light source illuminates the microperforations (e.g., passes light through the microperforations) from the opposite side of the material. If desired, the microperforations may be filled with a transparent material such as a clear epoxy material. As one example, the microperforations may be formed with a tapered shape (e.g., the width of the microperforations may increase from a minimum width at the outer surface of backing  56  (e.g., the surface closest to the exterior environment) to a maximum width at the inner surface of backing  56  (e.g., the surface closest to the interior of device  10 ). Alternatively, the microperforations may have a relatively straight shape (e.g., a uniform diameter through backing  56 ). With one suitable arrangement, each of the microperforations in device  10  may have a diameter of approximately 30 micrometers and the pitch (center-to-center spacing) of the microperforations may be approximately 200 micrometers. If desired, the pitch of the microperforations may be less than 200 micrometers, greater than 200 micrometers, less than 500 micrometers, less than 1 millimeter, etc. As one example, the pitch of the microperforations may be in the range of 100 micrometers to 300 micrometers. 
         [0057]      FIGS. 4 and 5  illustrate two ways in which the microperforations in region  58  of backing  56  may be formed. As one example, microperforations in region  58  of backing  56  may be formed by selectively removing portions of backing  56  using a laser cutting process. As shown in the  FIG. 4  example, lasers may cut microperforations in region  58  of backing  56  by directing laser light along direction  60  towards backing  56 . Alternatively, as shown in the  FIG. 5  example, lasers may cut microperforations in region  58  of backing  56  by directing laser light along direction  64  through glass cover  54  towards backing  56 . The microperforations may have, for example, a diameter in the range of 0.05 to 1.0 mm. If desired, the microperforations may have a diameter that is less than 0.05 mm. 
         [0058]    As shown in  FIG. 5 , sensors such as sensor  62  may be mounted beneath cover glass  54  in device  10  (e.g., after the microperforations have been formed). In particular, sensor  62  may be mounted under cover glass  54  (e.g., a glass substrate) and region  58  of backing  56  (e.g., a microperforated region of backing  56 ). With this type of arrangement, radiation required for the operation of sensor  62  may pass through cover  54  and region  58  of backing  56 . Sensor  62  may include one or more emitters and/or detectors that sense attributes of the environment around device  10 . Sensors  62  may, for example, be an infrared light sensor or visible light sensor for making ambient light measurements. 
         [0059]    If desired, cover  54  may extend substantially across the entire front face of device  10  (e.g., the face shown in  FIG. 1  which includes button  19 , display  16 , and port  23 ). This type of arrangement may create a smooth surface and may also enhance the aesthetic appearance of device  10 . Backing  56  may also extend substantially over the front face of device  10 . As shown in the example of  FIG. 6 , cover  54  may have holes in regions  70  and  72  and backing  56  may have holes in regions  68 ,  70 , and  72 . The holes in cover  54  and backing  56  may allow display  16  to emit light through cover  54 , button  19  to be accessed by a user, and sound and radiation (light) to pass through cover  54  to port  23 . 
         [0060]    As shown in  FIG. 6 , device  10  may include sensors  74  (e.g., sensors  62 ). Sensors  74  may include an emitter and detector pair configured as a proximity sensor and an ambient light sensor, as an example. Sensors  74  may be mounted underneath cover  54  and backing  56 . As described in connection with  FIGS. 4 and 5 , the backing  56  to cover  54  may have a plurality of small holes (microperforations) above each of the sensors  74  to allow radiation to pass between the sensors and the external environment. 
         [0061]    With one suitable arrangement, microperforations in backing  56  of cover  54  may be optimized to maximize the performance of the sensors  74 . With another suitable arrangement, the microperforations in backing  56  may be optimized to maximize the aesthetic appearance of device  10  (e.g., to minimize the visibility of the microperforations of a user of device  10 ). The microperforations in backing  56  may be designed to achieve a desired balance between sensor performance and aesthetic appearance. In general, sensor performance may be increased by increasing the number of microperforations, increasing the size of the microperforations, decreasing the distance between each microperforation, etc. In contrast, aesthetic appearance (e.g., the invisibility of the microperforations and underlying sensors) may generally be increased by decreasing the number of microperforations, decreasing the size of the microperforations, increasing the distance between each microperforation, etc. 
         [0062]    If desired, one or more of the sensors  74  may include a camera. As an example, sensor  75  may be a camera. If desired, whole portions of backing  56  (rather than microperforations) may be removed above sensor  75 . With one arrangement, the portion of backing  56  inside outline  66  may be removed. This type of arrangement may improve the performance of camera  75  by increasing the amount of light that reaches the camera  75 . 
         [0063]    A close-up of the microperforations in backing  56  (e.g., a light mask associated with cover  54 ) is shown in  FIG. 7 . As the example of  FIG. 7  shows, backing  56  may include a plurality of relatively small perforations  76  (holes) in which the backing material (e.g., paint, metallic layer, etc.) has been removed. Each of the perforations  76  may be evenly spaced from other perforations  76  (e.g., the perforations  76  may be formed in a pattern or an array). As an example, the perforations  76  may have a diameter of approximately 75 microns. If desired, each of the perforations  76  may have a diameter that is more than 75 microns or a diameter that is less than 75 microns. In general, the perforations  76  may be formed in any suitable shape and may be arranged in any suitable manner (e.g., in an array, in a pattern, randomly, etc.). The perforations  76  may allow radiation to pass between sensors and the environment. The perforations  76  may be arranged in an array. With one suitable arrangement, the microperforations  76  may be formed by using a laser to remove the backing material at the location of each microperforation  76  (e.g., by starting with a complete backing layer and creating microperforations). Alternatively, microperforations  76  may be formed as the backing material is formed on cover  54 . For example, backing  56  may be printed onto cover  54  (e.g., using screen printing techniques) and the microperforations  76  may be formed during the printing process (e.g., microperforations  76  may be formed by printing backing  56  onto cover  54  using a pattern that does not print backing material onto the microperforations  76 ). 
         [0064]    As described in connection with  FIG. 1 , device  10  may include a display such as display  16  that is configured to minimize light leakage. An example of a display such as display  16  that includes structures to reduce light leakage is shown in  FIG. 8 . 
         [0065]    As shown in  FIG. 8 , display  16  may include one or more light sources such as light emitting diodes  82  (e.g., a back light for display  16 ). Light emitting diodes  82  may be arranged along a top edge of display  16  and the light from diodes  82  may be distributed throughout display  16  using a light guide. Each of the light emitting diodes  82  may be formed from a light emitting diode that produces white light. In general, display  16  may include any suitable light source such as a white light emitting diode (LED), a combination of red, blue, and green light emitting diodes, a cold cathode fluorescent lamp (CCFL), an incandescent light bulb, an electroluminescent panel (ELP), a hot cathode fluorescent lamp (HCFL), other suitable light sources, or a combination of these and other light sources. 
         [0066]    Display  16  may include a connection interface  84 . Connection interface  84  (e.g., a connector) may convey signals between display  16  and circuitry in device  10  such as processing circuitry  36  and video processing circuitry in device  10 . Connection interface  84  may be based on any suitable type of interface. If desired, connection interface  84  may be formed from a flex circuit. 
         [0067]    The back face of display  16  (e.g., the face of display  16  opposite the face that displays images for a user) may be substantially covered by a reflector  78 . If desired, reflector  78  may be replaced with a planar backing structure rather than a reflecting structure. Reflector  78  may also be referred to as a planar backing structure. Reflector  78  may cover a light guide layer  86  in display  16 , as one example. Layer  86  may be located substantially underneath reflector  78  in  FIG. 8  and is therefore not shown separately in  FIG. 8 . Generally, reflector  78  helps to direct light towards the front face of display  16  and thereby increase the efficiency of display  16  by redirecting light that would otherwise escape through the back face of display  16 . At the interface of reflector  78  and chassis  94  (e.g., a plastic support structure) or another portion of display  16 , light may escape from display  16  (e.g., light may exit display  16  not through the desired display face or front face). This can lead to an unsightly condition in which light that has escaped from the rear face or sides of display  16  can enter the interior of device  10  and illuminate cracks or gaps in housing  12  of device  10 . 
         [0068]    Light leakage can be reduced by providing display  16  with opaque member  80 . Opaque tape  80  may be, as an example, a double-sided tape (e.g., a tape with adhesive on two sides). Opaque tape  80  may help to reduce or eliminate light leakage from display  16  by limiting the amount of light that can escape from the gap between reflector panel  78 , the underlying layers of display  16  such as light guide  86 , and chassis  94 , as an example. Tape  80  may cover the gap between panel  78  and chassis  94 . With one suitable arrangement, tape  80  may be formed from a black tape. If desired, tape  80  may be formed from a tape which is white on the side placed against panel  78  and chassis  94  and that is black on the opposite side. As an example, tape  80  may be added to the interior of display  16  (e.g., tape  80  applied to an interior surface of chassis  94  and panel  78 ). With this type of arrangement, the light leakage from display  16  may be reduced without negatively affecting the white balance of display  16 . 
         [0069]    While tape  80  only extends across two of the edges of reflector  78  in the  FIG. 8  example, in general tape  80  may be formed on any suitable portions of reflector  78 . If desired, tape  80  may extend around the entire perimeter of reflector  78 . 
         [0070]    Display  16  may be formed from a plurality of layers held together in a chassis. For example, as shown in  FIG. 9 , display  16  may include a glass panel layer  88 , a brightness enhancement film (BEF)  90 , a diffuser film  92 , light guide  86 , and reflector  78 . These layers may be sandwiched together and supported by chassis  94  (e.g., a plastic support structure). With one suitable arrangement, chassis  94  may be formed from a black material or may be formed from a material that is white on the inward facing sides of chassis  94  and that is black on the outward facing sides of chassis  94  (e.g., the exterior surface of chassis  94 ). This type of arrangement may help to reduce light leakage from display  16 . 
         [0071]    Light guide  86  may be coupled to light source  82  (shown in  FIG. 8 ) of display  16 . Light guide  86  may serve to evenly distribute the light from light source  82  across display  16 . 
         [0072]    As discussed in connection with  FIG. 8 , reflector  78  may redirect any light that is heading away from the desired direction for display  16 . For example, it is desirable for light to be emitted by display  16  along direction  96 . Reflector  78  may therefore redirect light that is headed in the direction  97  so that the redirected light is heading in the direction  96 . 
         [0073]    Diffuser film  92  may even out the light distributed by light guide  86 . As an example, the light distributed by light guide  86  may be somewhat more intense (e.g., brighter) near light source  82  and somewhat less intense away from light source  82 . Diffuser film  92  may help to counter the uneven intensity of light distributed by light guide  86  by diffusing light away from the higher intensity regions (near light source  82 ) towards the lower intensity regions (at the far end of display  16  opposite light source  82 ). 
         [0074]    Brightness enhancement film  90  may enhance the brightness of display  16 . With one suitable arrangement, film  90  may have a prismatic structure (or other suitable structure) and may refract light along direction  96 , if the light hits the prismatic structure at a particular angle, and may reflect the rest of the light (e.g., via an total internal reflection) back towards reflector  78  (e.g., along direction  97 ). If desired, film  90  may be a multi-layer optical film. With another suitable arrangement, film  90  may be used to increase the brightness of display  16  by managing the polarization of light that enters glass panel  88 . Because glass panel  88  may include one or more polarizers, managing the polarization of light using film  90  can increase the efficiency and brightness of display  16 . With this type of arrangement, film  90  may selectively pass a light in a particular polarization to panel  88  (e.g., a polarization that may be aligned with a polarizer in panel  88 ) while reflecting other polarizations back towards reflector  86  (e.g., along direction  97 ). Because the light received by glass panel  88  is already in the correct polarization (in this example) less light may be absorbed by a polarizer in panel  88  and the overall amount of light emitted by display  16  along direction  96  may be increased. 
         [0075]    Glass panel  88  may include an LCD panel. A cross-sectional view of glass panel  88  is shown in  FIG. 10 . As an example, glass panel  88  may include bottom polarizer  98 , array glass  100 , thin film transistor and liquid crystal layer  102 , color filter glass  104 , and top polarizer  106 . 
         [0076]    With one suitable arrangement, light from light sources  82  may enter glass panel  88  along direction  108  and pass through polarizer  98 . Polarizer  98  may ensure that the light entering glass panel  88  shares a common polarization. 
         [0077]    After the light has passed through polarizer  98  and been polarized, the polarized light may pass through array glass  100 . Array glass  100  may be a substrate layer on which thin-film-transistors may be formed. The polarized light may then pass through thin film transistor and liquid crystal layer  102 . Layer  102  may include an array of liquid crystals each of which is controlled by a respective thin film transistor. As the polarized light passes through layer  102 , the liquid crystals in layer  102  may be used to selectively alter the polarization of the light. The amount by which a given liquid crystal changes the polarization of light passing through it will typically depend on control signals received from the thin film transistor associated with the liquid crystal. 
         [0078]    Color filter glass  104  may selectively filter the light received from layer  102  into an appropriate color. For example, each pixel in display  16  may be formed from three sub-pixels. Each sub-pixel may be formed from a single liquid crystal and may be used to produce one of the three primary colors red, blue, or green. Color filter glass  104  may then be used to filter the light coming from each sub-pixel into the appropriate primary color (e.g., filter glass  104  may be an array designed to turn the light from each red sub pixel into red light, the light from each blue sub pixel into blue light, and the light from each green sub pixel into green light). 
         [0079]    Polarizer  106  may then filter the light before it leaves glass panel layer  88 . With one arrangement, polarizer  106  may be configured to pass light with a polarization that is ninety degrees from the polarization of light from polarizer  98 . With this arrangement, the amount to which liquid crystals in layer  102  change the polarization of light passing through layer  102  will determine the brightness of each individual pixel in display  16 . 
         [0080]      FIG. 11  illustrates how display  16  may be mounted to a mounting structure in device  10 . As shown in  FIG. 11 , display  16  may be mounted to a mounting structure  110  in device  10  using tape  80 . Tape  80  may be a double-side tape that also helps to prevent light leakage from display  16 . With another suitable arrangement, display  16  may be mounted to mounting structure  110  using adhesive. Mounting structure  110  may be a portion of housing  12  or, if desired, may be a structure in device  10  sometimes referred to as a midplane (e.g., an internal metal structure in device  10  that can be used as a mounting point for various internal components such as display  16 , storage devices, processing circuitry, etc.). 
         [0081]    A conventional display module  210  is shown in  FIG. 12 . Display module  210  includes reflector  212 , glass layer  214 , chassis  216 , and clear tape  218 . Clear tape  218  serves to hold reflector  212  and layer  214  together and also holds reflector  212  and layer  214  to chassis  216 . However, as shown in  FIG. 12 , light can escape from glass layer  214  and enter clear tape  218  as indicated by the arrow  220 . Once light has entered clear tape  218 , the light can leak from display module  210 . 
         [0082]    In contrast, opaque tape  80  can help to reduce or eliminate leak leakage from display  16  of  FIG. 1  by limiting the amount of light that can escape from display  16 . A close up view of the rear of display  16  is shown in  FIG. 13  which illustrates how opaque tape  80  helps to prevent light from escaping from display  16 . As shown in  FIG. 13 , opaque tape  80  may overlap a gap  81  between reflector layer  78  and light guide  86 . Tape  80  may also hold reflector layer  78  and light guide  86  to chassis  94 , if desired. Because tape  80  is formed from an opaque material such as an opaque polymer, tape  80  will help to prevent light leakage from any gaps (e.g., gaps  81 ) between reflector  78  and light guide  86  in display  16 . 
         [0083]    If desired, tape  80  may be formed from a transparent material. With this type of arrangement, an opaque material may be applied to the exterior of tape  80  to reduce light leakage. For example, a black paint may be applied to the exterior of a clear version of tape  80  to effectively make tape  80  opaque. 
         [0084]    If desired, device  10  of  FIG. 1  may include a compression spring that can be fully compressed without deforming. The compression spring may be part of a resilient button mechanism, as one example. In general, device  10  may include one or more compression springs. The compression springs may sometimes be referred to as variable cantilever compression springs.  FIG. 14  illustrates one potential variable cantilever compression spring  114  that could be a part of device  10 . Spring  114  may be formed from a single piece of metal with an elongated flat section  116 , first curved portion  118 , second curved portion  124 , and contact member  126 , as an example. Portions  124  and  116  may sometimes be referred to as curved structure  124  and elongated planar structure  116 . Curved structure  124  may be coupled to elongated planar structure  116  at one of the ends of curved structure  124 . First curved portion  118  may include two bends  120  and  122 . With another suitable arrangement, curved section  124  may be directly connected to section  116  (e.g., curved section  118  may be removed). Portion  124  may have a relatively constant upward curvature over the majority of its length. If desired, spring  114  may be configured so that bends  120  and  122  in section  118  undergo substantially no elastic or plastic deformation when spring  114  is compressed. 
         [0085]    With one suitable arrangement, spring  114  may be referred to as a variable cantilever spring because of its dynamic response to increasing compression. For example, the length of the cantilever of spring  114  (e.g., curved portion  124 ) may dynamically decrease as spring  114  is compressed. The length of the cantilever of spring  114  may be the distance between the contact region  126  and the closest point of contact between curved member  124  and structure  116 . In this configuration, when spring  114  is relatively uncompressed, the length of the cantilever will essentially be the full length of member  124  and, when spring  1214  is partially compressed, the length of the cantilever will be reduced relative to the full length of member  124 , thereby stiffening spring  114  as the spring is compressed. The length of the cantilever may be reduce by an amount proportional to the amount spring  114  is compressed. In contrast, the length of the cantilever of a conventional cantilevered spring is constant and does not change as the conventional spring is compressed. 
         [0086]    Spring  114  may be relatively resistant to fatigue. As an example, the curved portion  118  of spring  114  typically experiences relatively high stress levels during the manufacture of spring  114  (e.g., because curved portion  118  may include the sharpest bends in spring  114 ) and experiences relatively low stress levels during normal use (e.g., compression and release of spring  114 ). In contrast, curved portion  124  typically experiences relatively low stress levels during manufacturing and experiences relatively high stress levels during normal use. This type of arrangement may increase the resistance of spring  114  to metal fatigue relative to conventional spring designs in which the sharpest bends are prone to breakage. 
         [0087]    With one suitable arrangement, the elongated section  116  of spring  114  may be used as a first contact or attachment point to connect or attach spring  114  to a desired structure in device  10 . Contact member  126  may be used a second contact or attachment point to connect or attach spring  114  to a desired structure in device  10 . As spring  114  is compressed, contact member  126  may be depressed towards section  116  of spring  114 . The point of contact between sections  116  and  124  of spring  114  may continually shift (e.g., progressively curve away from section  118 ) as spring  114  is compressed. For example, when spring  114  is in its natural state (e.g., no force is pressing member  126  towards section  116 ), the point of contact between sections  116  and  124  may be in region  122  of curved portion  124 . As spring  114  is compressed, the point of contact between sections  116  and  124  may shift from section  118  towards member  126 . The point of contact may shift continuously as spring  114  is compressed or may shift incrementally as spring  114  is compressed (e.g., curved section  124  may be formed from a plurality of straight sections with bends between them while maintaining the overall shape of the section  124  shown in  FIG. 14 ). When spring  114  is completely compressed (e.g., member  126  is pressed directly against section  116 ), section  124  may lie relatively flat against  116 . The arrangement of  FIG. 14  helps to ensure that spring  114  does not undergo plastic deformation even when spring  114  is completely compressed. 
         [0088]    A side view of spring  114  is shown in  FIG. 15 . As shown in  FIG. 15 , spring  114  may have an uncompressed height of approximately 1.85 mm as indicated by arrows  130  (e.g., spring  114  may have an uncompressed height in the range of 1.50 mm to 2.00 mm). Contact member  126  may have a thickness of approximately 0.19 mm as indicated by arrows  128  (e.g., a thickness in the range of 0.1 mm to 0.5 mm). As one example, curve  124  may have a bend radius of approximately 2.75 mm when spring  114  is uncompressed (e.g., a bend radius in the range of 2.0 mm to 3.5 mm). Curved portion  118  may have a thickness of approximately 0.32 mm as indicated by arrows  134  (e.g., a thickness in the range of 0.1 mm to 0.5 mm). The second bend  122  of curved portion  118  may contact section  116  or, if desired, may be separated from section  116  by a gap of approximately 0.20 mm as indicated by arrows  132  (e.g., a gap in the range of 0.01 mm or less to 0.5 mm). Section  124  may have an uncompressed length (from curved portion  120  to contact member  126 ) of approximately 3.48 mm as indicated by arrows  158  (e.g., a length in the range of 2.5 mm to 5.0 mm). 
         [0089]    A bottom view of the variable cantilever spring  114  is shown in  FIG. 16 . As  FIG. 16  illustrates, section  116  of spring  114  may include a contact patch  140  and a floating patch  142 . The floating patch  142  of spring  114  may extend approximately 1.5 mm as indicated by arrows  136  from curved portion  118  towards contact patch  140 . With one suitable arrangement, floating patch  142  may not be mounted to any other structure (e.g., patch  142  may freely flex as spring  114  is compressed). With this type of arrangement, spring  114  may be mounted in device  10  by securing contact patch  140  of spring  114  to a suitable mounting structure. As one example, patch  140  may be soldered to a mounting structure in device  10 . In general, any suitable portion of spring  114  such as patch  140  or patch  142  (if desired) may be mounted to a structure in device  10  using any suitable means such as an adhesive, a tape, a mechanical fastener, by soldering, by another suitable means, or by a combination of these and other means. 
         [0090]    A top view of spring  114  is shown in  FIG. 17 . As shown in  FIG. 17 , contact portion  126  of spring  114  may include a contact area that is approximately 1.00 mm in length as indicated by arrows  148 . With one suitable arrangement, contact portion  126  of spring  114  may extend across the shaded region of  FIG. 17 . With one suitable arrangement, spring  114  may have a width in the range of approximately 0.7 to 0.9 mm as illustrated by arrows  146  and may have a length of approximately 4.65 mm as illustrated by arrows  144 . 
         [0091]    Spring  114  may be formed from any suitable elastic material such as a spring metal. For example, spring  114  may be formed from steel, bronze, titanium, copper, other suitable elastic materials, or a combination of these and other suitable materials. With one suitable arrangement, spring  114  may be formed from a beryllium copper alloy with a thickness of approximately 0.08 mm and with a Vickers Pyramid Number (HV) in the range of approximately 300-340. If desired, spring  114  may be plated (e.g., to reduce contact resistance). As an example, some or the entire surface of spring  114  may be plated with gold (or other suitable material). With one suitable arrangement, contact portion  126  (e.g., the shaded region in  FIG. 17 ) may be plated with gold with a plating thickness in the range of approximately 0.3 micrometers to 0.45 micrometers. Spring  114  may also include nickel plating between the gold plating and spring  114 . For example, spring  114  may include a nickel plating sometimes referred to as a barrier layer with a thickness in the range of 1.0 to 1.5 micrometers. If desired, the nickel plating or barrier layer may extend over the entire surface of spring  114 . In general, spring  114  may include any suitable combination of platings and barrier layers formed from any suitable materials. With one suitable arrangement, spring  114  may have a contact resistance (e.g., a resistance between an external member and spring  114  through contact region  126 ) of approximately 0.005 ohms with a contact force of approximately 0.3 newtons (N). 
         [0092]    If desired, spring  114  may include a structure which increases the uncompressed height of the spring following a nearly complete or complete compression of spring  114 . For example, as shown in  FIG. 18 , the tip of spring  114  (e.g., the portion of spring  114  near contact patch  126 ) may be curved back towards the base of spring  114  (e.g., section  116  of spring  114 ) as illustrated by solid line  153  of  FIG. 18 . If spring  114  is compressed sufficiently (e.g., spring  114  is compressed to the position indicated by the dotted line  150 ), the tip of spring  114  may be bent away from the base of spring  114  (e.g., the tip of spring  114  may undergo plastic deformation). After the tip of spring  114  is bent away from the base of spring  114 , the tip may rest in the position of dotted line  152  when the spring is uncompressed. This type of arrangement may be useful in increasing the uncompressed height of the spring following a relatively large compression. The resiliency of spring  114  may therefore be increased as a complete compression of spring  114  increases the distance that the spring  114  can be compressed. 
         [0093]    If desired, spring  114  may be used to stiffen a mounting structure. Section  140  of spring  114  may be used to stiffen a mounting structure such as mounting structure  156 . Mounting structure  156  may include any suitable structure such as a printed circuit board and a flex circuit. With this type of arrangement, a component  154  may be mounted to mounting structure  156  opposite spring  114 . By utilizing spring  114  as a stiffener of mounting structure  156 , component  154  may be mounted to a more flexible mounting structure  156  than would otherwise be practical (e.g., without having to add an addition stiffening structure, thereby reducing the number of components required). Component  154  may include any suitable component such as a flex circuit connector, processing circuitry, storage, input-output circuitry, etc. 
         [0094]    Device  10  may include one or more springs  114  as part of a button mechanism. As one example, device  10  may include two springs  114  that convey signals from a button such as button  19  between a pair of flex circuits as shown in  FIG. 19 . While the example of  FIG. 19  shows the two springs  114  arranged at different distances from button  19 , springs  114  may be arranged side-by-side (i.e., at similar distances from button  19 ), if desired. 
         [0095]    The physical button  19  on the exterior surface of device  10  may be coupled to a switch mechanism  160  and a circuit board  162 , as an example. Circuit  162  may be any suitable type of circuit such as a flex circuit or a printed circuit board. Switch mechanism  160  may be based on a dome switch mechanism or any other suitable button mechanism. With a dome switch mechanism, the dome of mechanism  160  will collapse when button  19  is pressed by a user. When the dome of mechanism  160  collapses it completes a circuit between two conductive lines. With one suitable arrangement, each of the two springs  114  in  FIG. 19  may be coupled to a respective one of the two conductive lines through flex circuit  162 . Each of the two springs  114  may also be coupled to a respective conductive line that is coupled to circuitry  172  through circuit  166  and contact patch  168 . With this type of arrangement, when button  19  is pressed by a user and the dome switch mechanism  160  completes the circuit between the two conductive lines, a conductive loop may be formed that begins at circuitry  172 , that passes through the two springs  114  and button mechanism  160 , and ends at circuitry  172 . 
         [0096]    Contact patch  140  may be coupled to flex circuit  162 . If desired, the contact patch  126  of each spring  114  may bear against contact region  168  of flex circuit  166 . With one suitable arrangement, as one of the springs  114  is compressed, the contact patch  126  of the spring may slide along contact region  168  of circuit  166 . Contact region  168  may be plated with a suitable material. As an example, contact region  168  of flex circuit  166  may be plated with gold. 
         [0097]    Circuit  166  may be any suitable type of circuit such as a flex circuit or a printed circuit board and may be mounted on structure  170 , as an example. Structure  170  may be a speaker enclosure or other suitable structure. 
         [0098]    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.