PATENT DOCUMENT

Publication Number: US-9488504-B2
Application Number: US-201514804070-A
Country: US
Kind Code: B2

Title: Electronic device moisture indicators

Abstract:
Electronic devices may have sensitive circuitry. To determine whether an electronic device has been exposed to excessive amounts of moisture, the electronic device may be provided with a moisture indicator. The moisture indicator may have a wicking layer of white paper and a red dye layer. If a portion of the moisture indicator is exposed to moisture, red dye may bleed into the white paper. The moisture indicator may be mounted in an input-output port opening or other portion of the electronic device where the state of the moisture indicator is visible. The moisture indicator may have sealed edges to reduce sensitivity to small amounts of moisture intrusion. Different regions of the moisture indicator may be provided with different sensitivities by forming structures that have altered moisture flow properties, by altering wicking layer thicknesses, or by otherwise spatially modifying moisture sensitivity.

Claims:
What is claimed is: 
     
       1. A portable electronic device, comprising:
 a housing having an opening in an exterior surface of the housing; and 
 a moisture indicator in the opening, wherein the moisture indicator comprises a wicking layer and a dye layer, wherein the entire wicking layer is overlapped by the dye layer, wherein the wicking layer has a first region with a first moisture sensitivity and has a second region with a second moisture sensitivity, and wherein the first moisture sensitivity is different than the second moisture sensitivity. 
 
     
     
       2. The portable electronic device defined in  claim 1 , wherein the moisture indicator comprises:
 a moisture barrier layer interposed between the wicking layer and the dye layer. 
 
     
     
       3. The portable electronic device defined in  claim 2 , wherein the moisture barrier layer comprises at least one opening. 
     
     
       4. The portable electronic device defined in  claim 3 , wherein the at least one opening comprises a pattern of openings that makes a first part of the moisture barrier layer more porous than a second part of the moisture barrier layer. 
     
     
       5. The portable electronic device defined in  claim 3  wherein the at least one opening comprises at least a first hole in a first part of the moisture barrier layer and at least a second hole in a second part of the moisture barrier layer, and wherein the first hole covers a larger area of the moisture barrier layer than the second hole. 
     
     
       6. The portable electronic device defined in  claim 3  wherein the at least one opening in the moisture barrier layer comprises a pattern of holes that allow water to pass more readily through a first part of the moisture barrier layer than through a second part of the moisture barrier layer. 
     
     
       7. The portable electronic device defined in  claim 3  wherein the at least one opening extends from a first side of the moisture barrier layer to a second side of the moisture barrier layer. 
     
     
       8. A portable electronic device comprising:
 a housing having an opening in an exterior surface of the housing; and 
 a moisture indicator in the opening, wherein the moisture indicator comprises:
 a dye layer; 
 a first wicking layer formed adjacent the dye layer; and 
 a second wicking layer that covers some but not all of the first wicking layer. 
 
 
     
     
       9. The portable electronic device defined in  claim 8 , wherein the first wicking layer overlaps the entire dye layer. 
     
     
       10. The portable electronic device defined in  claim 8 , wherein the moisture indicator further comprises a third wicking layer. 
     
     
       11. The portable electronic device defined in  claim 10 , wherein the third wicking layer covers some but not all of the second wicking layer. 
     
     
       12. The portable electronic device defined in  claim 11 , wherein the second wicking layer is in direct contact with the first wicking layer, and wherein the third wicking layer is in direct contact with the second wicking layer. 
     
     
       13. The portable electronic device defined in  claim 8 , wherein the moisture indicator further comprises first and second moisture barrier layers that are sealed together along at least one sealed edge of the moisture indicator. 
     
     
       14. The portable electronic device defined in  claim 13 , wherein the dye layer, the first wicking layer, and the second wicking layer are interposed between the first and second moisture barrier layers. 
     
     
       15. A portable electronic device comprising:
 a housing having an opening in an exterior surface of the housing; and 
 a moisture indicator in the opening, wherein the moisture indicator comprises dye and a wicking layer formed adjacent the dye, wherein the wicking layer has a first portion with a first thickness and a second portion with a second thickness, wherein the first and second thicknesses are different, and wherein the wicking layer smoothly changes in thickness from the first thickness at the first portion to the second thickness at the second portion. 
 
     
     
       16. The portable electronic device defined in  claim 15 , wherein the entire wicking layer is adjacent the dye. 
     
     
       17. The portable electronic device defined in  claim 8 , wherein the dye layer overlaps the entire first wicking layer. 
     
     
       18. The portable electronic device defined in  claim 17 , wherein the second wicking layer is adjacent to and in direct contact with the first wicking layer. 
     
     
       19. The portable electronic device defined in  claim 18 , wherein the moisture indicator further comprises a third wicking layer that covers some but not all of the second wicking layer, wherein the third wicking layer is adjacent to and in direct contact with the second wicking layer, and wherein the second wicking layer is interposed between the first wicking layer and the third wicking layer. 
     
     
       20. The portable electronic device defined in  claim 1 , wherein the first region vertically overlaps the dye layer, wherein the second region vertically overlaps the dye layer, and wherein the first and second regions are not vertically overlapping.

Description:
This application is a continuation of patent application Ser. No. 13/868,821, filed Apr. 23, 2013, now U.S. Pat. No. 9,086,298, which is a division of patent application Ser. No. 12/472,192, filed May 26, 2009, now U.S. Pat. No. 8,440,274, all of which are hereby incorporated by reference herein in their entireties. This application claims the benefit of and claims priority to patent application Ser. No. 12/472,192, filed May 26, 2009, and patent application Ser. No. 13/868,821, filed Apr. 23, 2013, now U.S. Pat. No. 8,440,274. 
    
    
     BACKGROUND 
     This invention relates generally to electronic devices, and more particularly, to moisture indicators for electronic devices. 
     Many electronic devices are susceptible to damage when exposed to excessive moisture. Large stationary devices such as televisions and desktop computers can typically be located in an area of a user&#39;s home or office where the likelihood of exposure to liquids can be reduced. For example, a television can be located in a safe environment such as a user&#39;s living room, rather than in an outdoors location where the television might be exposed to rain. 
     Safeguarding other electronic devices can be more difficult. For example, handheld electronic devices and other portable electronic devices are, by their very nature, at a greater risk of accidental exposure to moisture. It is not uncommon for users to carry sensitive equipment such as cellular telephones in a pocket when traveling outdoors. If a user receives a telephone call during a rainstorm, the user might use the cellular telephone before seeking shelter from the rain. Devices may also be left in environments in which condensation may lead to moisture infiltration. 
     Although devices can be made somewhat resistant to damage from small amounts of moisture, it is not feasible to completely waterproof most devices. For example, device ports may create potential locations through which moisture can reach the circuitry of an electronic device. Covering all of the ports in a device to prevent moisture damage might make the device too cumbersome to use. Moisture barrier structures may also add undesirable bulk and may make devices unsightly and expensive. 
     Because of these practical considerations, electronic devices are generally somewhat resistant to moisture exposure, but are not completely waterproof. Designing a device in this way maximizes user enjoyment and use of the device, but does not eliminate all risk of moisture-related damage. 
     Users are generally aware of the moisture sensitivity limits of modern electronic devices. For this reason, users take care to avoid submerging electronic devices in liquid. Even a careless user would not expect an electronic device such as a cellular telephone to be undamaged if fully immersed in liquid. 
     At the same time, manufacturers try to ensure that devices do not fail immediately upon exposure to trivial amounts of moisture. Overly sensitive devices would require frequent attention from customer service personnel. 
     Even though electronic devices are generally designed to be robust enough to withstand momentary exposure to trivial amounts of moisture, accidents can happen. For example, a user may drop a device into a body of water. When a device that has been damaged in this way stops working properly, the user may decide to return the device to the manufacturer for repair. 
     A large manufacturer of electronic devices can expect to receive returns from customers that have exposed their devices to excessive amounts of water. Often the damaged devices are dry when they are returned. To determine whether or not a device has been submerged in liquid, manufacturers often include moisture infiltration indicators (sometimes called “water dots” or “moisture indicators”) in their devices. If the water dot in a returned device has not been activated, the manufacturer can conclude that damage to the device was caused by dropping the device onto a hard surface or another damaging event other than liquid exposure. If the water dot has been activated, the manufacturer can conclude that the device has failed due to excessive exposure to liquid. 
     The use of water dots to test for liquid exposure helps manufacturers to evaluate warranty claims and debug possible failure mechanisms. To avoid adversely affecting device aesthetics, it is often desirable to place water dots in discrete locations. At the same time, it may be desirable to place water dots in locations that are readily accessible by service personnel, so that a returned device does not need to be disassembled to examine the status of the water dot. 
     As an example, a water dot may be placed in a recessed portion of a device such as a device port. When a water dot is located in a device port, the water dot can be quickly examined by service personnel, but will not be unsightly to users. 
     Particularly when water dots are located in relatively exposed positions such as these, the water dots may become highly sensitive to moisture damage. This may make it impossible for service personnel to determine whether a device has failed from a small amount of moisture exposure of the type that would normally be covered by the manufacturer&#39;s warranty or whether the device has failed due to a complete submersion of the device in liquid. 
     It would therefore be desirable to be able to provide improved moisture indicator structures for electronic devices. 
     SUMMARY 
     An electronic device such as a portable electronic device may contain sensitive components. For example, an electronic device may contain printed circuit boards on which circuit components are mounted. 
     To avoid damage to the electronic device, a user should avoid any exposure to moisture. Sometimes, however, trivial amounts of moisture infiltrate an electronic device. A moisture indicator (“water dot”) may be provided to monitor exposure of the electronic device to moisture. 
     To distinguish between situations in which an electronic device has been immersed in liquid or otherwise exposed to large amounts of moisture and situations in which the electronic device has been exposed to only a relatively small amount of moisture, the moisture indicator may be provided with a sealed edge. The sealed edge may reduce the sensitivity of the moisture indicator. The moisture indicator may have an unsealed edge through which moisture can enter the moisture indicator. 
     The moisture indicator may be mounted to a connector in an input-output port or other opening of the electronic device. This allows the status of the moisture indicator to be viewed without disassembling the electronic device. The moisture indicator may be mounted within the opening so that the unsealed edge is located within the interior of the electronic device. The sealed edge can be mounted in the end of the opening that is closer to the exterior of the device. Because the sealed edge blocks moisture, trivial amounts of moisture that reach the moisture indicator only along its sealed edge will not cause the moisture indicator to change color. 
     The moisture indicator may be provided with regions of different sensitivity. Different regions of the moisture indicator may be separated from each other using moisture-flow-altering structures. These structures may be formed by introducing moisture-blocking substances into a wicking layer at selected locations. Different wicking layer thicknesses and interposed layers of perforated moisture blocking material may also be used to provide the moisture indicator with regions of varying moisture sensitivity. 
     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 that includes a moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 2A  shows how a moisture indicator may have a first appearance when it has not been exposed to moisture in accordance with an embodiment of the present invention. 
         FIG. 2B  shows how a moisture indicator of the type shown in  FIG. 2A  may have a second appearance when it has been exposed to moisture in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of a connector structure and an associated moisture indicator of the type that may be used in an electronic device such as the electronic device of  FIG. 1  in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram showing how a moisture indicator may be located at the lower end of an electronic device in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of a conventional moisture indicator. 
         FIG. 6  is a cross-sectional side view of a moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 7  is a top view of a conventional moisture indicator showing directions from which moisture may enter the moisture indicator. 
         FIG. 8  is a top view of a moisture indicator showing directions from which moisture may enter the moisture indicator and directions in which moisture entry is blocked in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of a moisture indicator showing how moisture can be blocked from entering the moisture indicator using an impermeable substance to seal an edge of the moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of a moisture indicator showing how moisture can be blocked from entering the moisture indicator by joining upper and lower moisture barrier layers along an edge of the moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 11  is a top view of an illustrative moisture barrier showing how a single opening may be formed in the otherwise sealed edge of a moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 12  is a top view of an illustrative moisture indicator showing how multiple openings may be formed in the sealed edge of a moisture indicator in accordance with an embodiment of the present invention. 
         FIG. 13  is a top view of an illustrative multi-region moisture indicator in accordance with an embodiment of the present invention. 
         FIGS. 14 and 15  are cross-sectional side views of an illustrative moisture indicator structure showing how a moisture indicator wicking layer may be provided with portions with different wicking properties in accordance with an embodiment of the present invention. 
         FIG. 16  is a cross-sectional side view of an illustrative moisture indicator structure showing how wax or other substances may be placed in two or more portions of a wicking layer in accordance with an embodiment of the present invention. 
         FIG. 17  is a cross-sectional side view of an illustrative moisture indicator structure showing how one or more regions of a wicking layer may be selectively thickened in accordance with an embodiment of the present invention. 
         FIG. 18  is a cross-sectional side view of an illustrative moisture indicator structure showing how a wicking layer structure may be selectively thickened using multiple layers of wicking material in certain areas in accordance with an embodiment of the present invention. 
         FIG. 19  is a cross-sectional side view of an illustrative moisture indicator structure showing how a wicking layer structure may be progressively thickened to spatially alter moisture indicator sensitivity in accordance with an embodiment of the present invention. 
         FIG. 20  is a cross-sectional side view of an illustrative moisture indicator structure showing how a wicking layer structure may be selectively thinned to spatially alter moisture indicator sensitivity in accordance with an embodiment of the present invention. 
         FIG. 21  is a top view of an illustrative moisture indicator structure having a moisture barrier layer with holes that lies between a wicking layer and a dye layer in accordance with an embodiment of the present invention. 
         FIG. 22  is a side view of an illustrative moisture indicator structure having a moisture barrier layer with holes that lies between a wicking layer and a dye layer in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Moisture infiltration indication structures may be provided for electronic devices. 
     The electronic devices may desktop computers, televisions, or other consumer electronics equipment. The electronic devices may also be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. If desired, portable electronic devices may 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. With one suitable arrangement, the portable electronic devices may be handheld electronic devices. 
     Electronic devices include circuitry. The circuitry typically includes electronic components such as integrated circuits and discrete devices such as capacitors, resistors, and inductors. Circuit components may be mounted on rigid and flexible printed circuit boards. 
     To determine whether an electronic device has been exposed to moisture, the electronic device may be provided with a moisture indicator. Moisture indicators, which are sometimes referred to as moisture intrusion indicators or water dots, may change color or otherwise alter their visual appearance when exposed to liquid. The state of a moisture indicator is therefore indicative of whether or not the electronic device has been handled properly. For example, a moisture indicator with an unchanged state indicates that a device has not been exposed to substantial amounts of moisture, whereas a moisture indicator with an activated state indicates that a device has been exposed to liquid. 
     To ensure that the moisture indicator is not overly sensitive, some or all of the edges of the moisture indicator may be sealed. 
     An illustrative electronic device is shown in accordance with an embodiment of the present invention is shown in  FIG. 1 . Device  10  of  FIG. 1  may be, for example, a handheld electronic device that supports cellular telephone voice and data functions, global positioning system capabilities, local wireless communications capabilities (e.g., IEEE 802.11 and Bluetooth®), and other wireless functions. Device  10  may have storage and processing circuitry that allows device  10  to run code. The code may be used in implementing functions such as internet browsing functions, email and calendar functions, games, music player functionality, etc. 
     Device  10  may have housing  12 . Antennas for handling wireless communications may be housed within housing  12  (as an example). Housing  12  may be formed of any suitable materials including, plastic, glass, ceramics, metal, other suitable materials, or a combination of these materials. Bezel  14  may be formed from a conductive material and may serve to hold a display or other device with a planar surface in place on device  10 . Bezel  14  may also form an aesthetically pleasing trim around the edge of device  10 . 
     Display  16  may be a liquid crystal display (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. An advantage of integrating a touch screen into display  16  to make display  16  touch sensitive is that this type of arrangement can save space and reduce visual clutter. 
     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 . Button  19  may be, for example, a menu button. Port  20  may contain a 30-pin data 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. 
     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 . Although shown schematically as being formed on the top face of electronic device  10  in the example of  FIG. 1 , buttons such as button  19  and other user input interface devices may generally be formed on any suitable portion of electronic device  10 . For example, a button such as button  19  or other user interface control may be formed on the side of electronic device  10 . Buttons and other user interface controls can also be located on the top face, rear face, or other portion of 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.). 
     Electronic device  10  may have ports such as port  20 . Port  20 , which may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, may be used as an input-output port (e.g., when connecting device  10  to a mating dock connected to a computer or other electronic device). Port  20  may contain pins for receiving data and power signals. Device  10  may also have audio and video jacks that allow device  10  to interface with external components. Typical ports include power pins to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data pins to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, a subscriber identity module (SIM) card port to authorize cellular telephone service, a memory card slot, etc. The functions of some or all of these devices and the internal circuitry of electronic device  10  can be controlled using input interface devices such as touch screen display  16 . 
     Device  10  may include one or more printed circuit boards. The printed circuit boards of device  10  may be formed from rigid printed circuit board material (e.g., fiberglass-filled epoxy). Flexible printed circuit boards (“flex circuits”) may be formed using sheets of flexible polymers such as polyimide (as an example). Rigid and flexible printed circuit boards may be used to mount integrated circuits such as storage devices, processors, application specific integrated circuits, radio-frequency transceivers and other wireless circuitry, and other circuits. The wireless circuitry may include antennas. Examples of locations in which antennas may be located in device  10  include region  18  at the lower end of device  10  and region  21  at the upper end of device  10 . 
     The circuitry within device  10  is generally not designed to be completely waterproof. As a result, excessive moisture may potentially damage device  10 . Damage due to extreme moisture exposure such as exposure when device  10  is immersed in liquid is generally due to mishandling. For example, a user may accidentally drop device  10  into a body of water. Device  10  is not designed to withstand this type of abuse and will therefore probably fail. If a user of device  10  seeks warranty coverage, it would be helpful to determine whether device  10  has been abused by submersion in liquid. 
     Other types of damage may arise when device  10  is exposed to more modest amounts of moisture. For example, a small amount of perspiration may enter device  10  in the vicinity of port  20  when a user is working out at the gym. As another example, a user may place device  10  in a cup holder in a car in which a small amount of condensation from a cold drink has collected. This small amount of water might also enter device  10  in the vicinity of port  20 . 
     Because device  10  is not designed to be waterproof, it is conceivable that these relatively small amounts of moisture may adversely affect proper device operation. It may be desirable to provide a user with warranty coverage in such circumstances, because the user did not abuse the device. 
     To distinguish between relatively large amounts of moisture infiltration and relatively small amounts of moisture infiltration in device  10 , moisture indicator structures may be provided in device  10  that can help measure different amounts of moisture exposure. Moisture indicators such as these may be located in any suitable portion of device  10 . For example, moisture indicators can be provided in the interior of device  10  adjacent to a printed circuit board or other sensitive circuitry. 
     In some circumstances, service personnel may want to quickly ascertain the moisture exposure status of a device without opening up the device to inspect an internally mounted moisture indicator. To accommodate this type of need and to ensure that moisture indicators are provided in portions of device  10  in which moisture is likely to intrude, device  10  may be provided with one or more moisture indicators in the vicinity of device ports. For example, device  10  may be provided with a moisture indicator in port  20 . By placing the moisture indicator in a portion of device  10  that is visible from the exterior of device  10 , the need to open up device  10  to check the status of the moisture indicator can be avoided. Other mounting arrangements for moisture indicators may be used if desired. A configuration in which a moisture indicator is mounted within port  20  in a location that is visible from the exterior of device  10  by service personnel is sometimes described herein as an example. 
     A moisture indicator is typically constructed from layers of different materials. For example, a moisture indicator may have a paper layer or other suitable wicking layer on which a dye layer is formed. The dye may be formed from any suitable colored substance and may sometimes be referred to as ink or pigment. When the wicking layer is exposed to moisture, the dye bleeds into the wicking layer and changes its appearance. The dye may be, for example, a red dye. The wicking layer may be, for example, white paper. 
     The behavior of a moisture indicator of this type is illustrated in  FIGS. 2A and 2B . As shown in  FIG. 2A , Moisture indicator  32  may have a visible surface  26 . Surface  26  may be, for example, a wicking layer that has been optionally covered with a transparent moisture barrier layer. In the example of  FIG. 2A , moisture indicator  32  has been mounted under hole  28  in member  30 . Member  30  may be part of a connector member in port  20  or may be any other suitable structural portion of device  10 . 
     Initially, moisture indicator  32  is unexposed to moisture. When moisture indicator becomes wet, however, the dye layer will bleed into the wicking layer. The resulting change in appearance of surface  26  (e.g., from white to red) is illustrated in  FIG. 2B . 
     Moisture indicator  32  may be mounted in any suitable portion of device  10 . An illustrative mounting arrangement that may be used in which moisture indicator  32  is mounted on a connector associated with port  20  is shown in  FIG. 3 . As shown in  FIG. 3 , connector  34  may have tab structures  36  that are used in securing connector  34  to device  10  in port  20 . Connector  34  may be, for example, a 30-pin connector. When it is desired to connect a 30-pin cable to device  10 , the head of the 30-pin connector may be inserted into connector  34  in opening  38 . 
     Member  30  of connector  34  may have registration pins  40 . Moisture indicator  32  may be formed from a series of planar layers. As shown in  FIG. 3 , holes  42  may be formed in the layers of moisture indicator  32  that match registration pins  40 . This may help to align moisture indicator to member  30  of connector  34 . Adhesive or other suitable fastening mechanisms may be used to secure moisture indicator  32  to member  30 . With the arrangement shown in  FIG. 3 , surface  26  ( FIGS. 2A and 2B ) of moisture indicator  32  faces downwards through hole  28  in member  30 . Service personnel can therefore examine the status of moisture indicator  32  by looking into hole  38  of connector  34  when connector  34  is mounted in the lower portion of device  10  to form port  20  ( FIG. 1 ). 
       FIG. 4  shows potential pathways for moisture entering device  10 . As shown in  FIG. 4 , device  10  may contain sensitive components  44  such as printed circuit board structures to which circuitry is mounted. Moisture indicator  32  may be mounted on a connector such as connector  34  of  FIG. 2  in port  20  so that the status of the moisture indicator can be visually examined through hole  28 . When located as shown in  FIG. 4 , moisture can reach moisture indicator  32  along lower edge  48  following paths  50  or can reach moisture indicator  32  along upper edge  46  along paths such as path  52 . 
     Proper operation of moisture indicator  32  can be achieved by adjusting its sensitivity so that trivial amounts of moisture exposure are distinguishable from excessive amounts of moisture exposure. With one suitable arrangement, the upper and lower planar surfaces of moisture indicator  32  may be covered by moisture barrier layers and some of the edges of the moisture barrier layers may be sealed to prevent moisture intrusion. For example, lower edge  48  may be sealed to prevent moisture from entering moisture indicator  32  along paths  50 , whereas upper edge  46  may remain unsealed to allow moisture to enter moisture indicator  32  along paths  52 . Small amounts of moisture may sometimes enter the device  10  along paths  50 , so it can be helpful to reduce the sensitivity of moisture indicator  32  to moisture exposure of this type. At the same time, moisture that has reached moisture indicator  32  after traveling along paths  52  is likely to have damaged sensitive components  44 , so it is helpful for this type of moisture exposure to activate moisture indicator  32 . 
     A cross-sectional side view of a conventional moisture indicator is shown in  FIG. 5 . As shown in  FIG. 5 , moisture indicator  54  may have white paper layer  60  and red dye layer  58 . Moisture indicator  54  may be mounted to the lower side of member  66  using adhesive  64 , so that visual inspection of the upper surface of moisture indicator  54  may be made in direction  77  through a hole in member  66 . The upper and lower planar surfaces of moisture indicator  54  may be sealed using lower moisture barrier layer  56  and upper moisture barrier layer  62 . Moisture barrier layers  56  and  62  are formed from polyethylene terephthalate (PET). Upper moisture barrier layer  62  is clear, so that the color of wicking layer  60  is visible from direction  77 . 
     The edges of conventional moisture indicators such as moisture indicator  54  of  FIG. 5  are not sealed. This allows moisture to enter wicking layer  60  from any edge of moisture indicator  54  that is exposed to moisture. For example, moisture may enter layer  60  along unsealed edge  72  following paths  70  and may enter layer  60  along unsealed edge  76  following paths  74 . Once moisture has entered wicking layer  60 , dye from layer  58  may bleed into wicking layer  60  along paths  68 . The resulting presence of dye in layer  60  may be observed visually from direction  77 . 
     To properly tailor moisture indicator sensitivity, some of edge portions of a moisture indicator may be sealed. An example is shown in the cross-section of  FIG. 6 . 
     As shown in  FIG. 6 , moisture indicator  32  may have wicking layer  82  and dye layer  80 . Wicking layer  82  may be formed from white paper or other suitable moisture-permeable material. Dye layer  80  may be formed from a red water-soluble dye or other suitable substance that bleeds into wicking layer  82  upon exposure to moisture. 
     Moisture indicator  32  may have moisture barrier layers such as upper moisture barrier layer  86  and lower moisture barrier layer  78  that cover the wicking layer  82  and dye layer  80 . Layers  78  and  86  may be formed from a moisture-repellent (impermeable) material such as polyethylene terephthalate (PET). Upper moisture barrier layer  86  may be transparent, so that the color of wicking layer  82  is visible from direction  98 . 
     Adhesive  88  or other suitable fastening mechanisms may be used to attach moisture indicator  32  to member  30 . Member  30  may be, for example, part of connector  34  of  FIG. 4  and may be located in a portion of device  10  where moisture indicator  32  is visible through hole  28  when viewed from direction  98 . 
     Upper moisture barrier  86  and lower moisture barrier  78  may be sealed using an impermeable (moisture-proof) material such as paint, adhesive, etc. As shown in  FIG. 6 , impermeable material  102  may be placed along edge  92  of moisture indicator  32  so that edge  92  is sealed to moisture. With this type of configuration, moisture that approaches moisture indicator  32  along path  94  will be blocked by the sealed moisture barrier layers along edge  92 , but moisture that approaches moisture indicator  32  along paths  100  will be able to enter wicking layer  82  through unsealed edge  84 . Once this moisture enters moisture indicator  32 , dye in layer  80  may bleed into wicking layer  82  along paths  96  to visually indicate that moisture has been detected. 
     By sealing edge regions of moisture indicator  32 , moisture indicator  32  can be desensitized. As a result, the presence of trivial amounts of moisture will not result in a positive moisture reading. If desired, sealed edges such as edge  92  may be located adjacent to the entrance of an opening in device  10 , where small amounts of moisture intrusion are most likely, whereas the unsealed portions of moisture indicator  32  such as unsealed edge  84  can be located further into the interior of device  10 . For example, edge  92  may be located along the lowermost edge of connector  34  in port  20  near the surface of device  10 , whereas edge  84  may be located along the uppermost edge of connector  34  (i.e., several millimeters or more inside device  10 ). 
     Any suitable edges of a moisture indicator may be sealed. A top view of a conventional moisture indicator  54  is shown in  FIG. 7 . As shown in  FIG. 7 , moisture indicator  54  may have registration holes  106  and may have a central portion  108  that is viewable through a hole in a connector such as connector  34  of  FIG. 3 . All of the edges (top, bottom, left, and right) of moisture indicator  54  of  FIG. 7  are unsealed edges such as edges  76  and  72  of  FIG. 5 . With this type of arrangement, moisture can enter moisture indicator  54  of  FIG. 7  from any direction  104 . 
     A moisture indicator with sealed edges is shown in  FIG. 8 . As shown in  FIG. 8 , moisture indicator  32  may have a central region  110  that can be aligned with hole  28  in member  30  ( FIG. 3 ). Moisture indicator  32  of  FIG. 8  may have a cross-section of the type shown in  FIG. 6 . Upper and lower barrier layers may be sealed along edges  92  and may be unsealed along edge  81 . This prevents moisture from entering moisture indicator  32  along paths  94 , but allows moisture to enter the wicking layer of moisture indicator  32  along paths  100 . By orienting moisture indicator  32  of  FIG. 8  so that lower sealed edge  92  of moisture indicator  32  is aligned with the lowermost edge of connector  34  ( FIG. 3 ) in port  20  ( FIG. 1 ), moisture indicator  32  can be prevented from being overly sensitive. Small amounts of moisture that come into contact with the portions of moisture indicator  32  along lower edge  92  will not cause moisture indicator  32  to change state. However, larger amounts of moisture, such as moisture resulting from immersion of device  10  in liquid, can enter moisture indicator  32  along unsealed edge  81  within the interior of device  10 . 
     Any suitable technique may be used for sealing edge portions such as edge portions  92 . With the illustrative arrangement of  FIG. 9 , an impermeable seal has been created between upper moisture barrier layer  86  and lower moisture barrier layer  78  by coating edge  92  with paint, adhesive, other substances that are liquid when applied but that transform into solids when cured, or other impermeable substances  102 . 
     Another possible arrangement is shown in  FIG. 10 . With the illustrative configuration of  FIG. 10 , upper moisture barrier layer  86  and lower moisture barrier layer  78  are joined along region  112  to ensure that edge  92  of moisture indicator  32  is sealed. Moisture barrier layer  86  and moisture barrier layer  78  may be sealed in region  112  using heat treatment (e.g., to melt or soften layers  86  and  78 ), using adhesive, using combinations of pressure, heat, and adhesive, using clips or other connective structures, or using any other suitable sealing techniques. 
     One or more edge portions of moisture indicator  32  may be left unsealed. As shown in  FIG. 11 , unblocked edge  84  of moisture indicator  32  may occupy only a fraction of the total upper edge of the moisture sensor, whereas all remaining edges  92  may be sealed (as an example).  FIG. 12  shows an illustrative configuration in which multiple edge segments  84 A and  84 B are unsealed and the remaining edge portions  92  are sealed. 
     By adjusting the sensitivity of moisture indicator  32  to moisture exposure, moisture indicator  32  can be configured to provide a desired amount of moisture intrusion status information. For example, moisture indicator  32  can be configured to alert service personnel to extreme exposures to moisture, but not trivial exposures to moisture (as an example). 
     If desired, moisture indicator  32  may be provided with multiple regions, each of which changes state (e.g., from white to red) under different moisture exposure conditions. The thickness of wicking layer  82  can influence the sensitivity of moisture indicator  32  to moisture, so one illustrative configuration for providing moisture indicator  32  with regions of varying moisture sensitivity involves providing moisture indicator  32  with regions of different wicking layer thickness. The movement of moisture through wicking layer  82  can also be influenced by introducing foreign substances into wicking layer  82 . For example, the flow of moisture can be influenced by incorporating an impermeable substance such as wax, paint, or adhesive into parts of wicking layer  82 . Additional configurations are also possible (e.g., using wicking layer materials with different properties, using blocking layers with holes or other shapes, using combinations of these arrangements, or other suitable configurations). 
     An illustrative moisture indicator with multiple regions is shown in  FIG. 13 . In the example of  FIG. 13 , moisture indicator  32  has an upper edge  84  that is unsealed and has right, left, and lower edges  92  that are sealed (i.e., that have moisture barrier layers that are connected together to prevent moisture intrusion). 
     Moisture indicator  32  of  FIG. 13  has four regions  114 A,  114 B,  114 C, and  114 D that are separated by three regions  116 A,  116 B, and  116 C. Regions  114 A,  114 B,  114 C, and  114 D may be, for example, regions of wicking material that are coated with transparent moisture barrier layer material. Regions  116 A,  116 B, and  116 C may be portions of moisture indicator  32  that have modified properties (e.g., through the introduction of moisture blocking materials such as wax into the wicking layer, through the thickening or thinning of the wicking layer, etc.). 
     With one suitable arrangement, which is sometimes described herein as an example, the presence of regions  116 A,  116 B, and  116 C may serve to impede moisture intrusion. This can help make the appearance of moisture indicator  32  more distinct and easier to interpret under a variety of moisture exposure conditions. For example, the presence of regions  116 A,  116 B, and  116 C may lead to an overall structure in which region  114 A is most sensitive to moisture, region  114 B is less sensitive to moisture intrusion than region  114 A, region  114 C is less sensitive to moisture intrusion than region  114 B, and region  114 D is the least sensitive region in moisture indicator  32 . In the absence of structures  116 A,  116 B, and  116 C, it might be difficult to distinguish between relatively small amounts of moisture exposure and relatively large amounts of moisture exposure. 
     When an arrangement of the type shown in  FIG. 13  is used, however, exposure to an extremely large amount of liquid may cause regions  114 A,  114 B,  114 C, and  114 D to all change from white to red, whereas exposure to a small amount of liquid might cause only regions  114 A and  114 B to turn red (as an example). The sizes of regions  116 A,  116 B, and  116 C may be identical (to provide moisture indicator  32  with a linear response characteristic) or may be progressively larger or smaller (e.g., to provide moisture indicator  32  with a logarithmic or exponential response). 
     One way in which to selectively impede the flow of moisture through moisture indicator  32  so that the individual states of regions such as regions  114 A,  114 B,  114 C, and  114 D can distinctly represent different amounts of moisture exposure involves introducing foreign substances into wicking layer  82 . This type of configuration is shown in  FIG. 14 . As shown in  FIG. 14 , wicking layer  82  may have a first portion under region  114 A and a second portion under region  114 B between which (in region  116 A) foreign substance  118  is introduced. The foreign substance in region  116 A may be, for example, a material such as wax (e.g., an impermeable material) that is resistant to the wicking of moisture. The presence of substance  118  impedes moisture flow from region  114 A to  114 B and therefore makes region  114 A more sensitive to moisture events than region  114 B. Because structures such as the structure in region  116 A of  FIG. 14  serve to impede the flow of moisture through wicking layer  82 , structures such as structure  116 A may sometimes be referred to as moisture flow impeding structures of moisture flow altering structures. 
     When substance  118  is impermeable, it may be desirable to limit the penetration depth of substance  118  into wicking layer  82 . A cross-sectional view of a portion of an illustrative moisture indicator  32  in which the depth of substance  118  is relatively shallow is shown in  FIG. 15  as an example. 
     As shown in  FIG. 16 , a given moisture indicator may have multiple regions such as regions  116 A and  116 B with different depths (in addition to or instead of having different widths). With the illustrative structures of  FIG. 16 , regions  114 A and  114 B are separated by a moisture flow impeding structure that is relatively shallow (structure  118 A or moisture flow impeding region  116 A), whereas regions  114 B and  114 C are separated by a moisture flow impeding structure that is relatively deep (structure  118 B in moisture flow impeding region  116 B). In this type of arrangement, the deep shape of the structure in region  116 B will ensure that region  114 C will only change state when moisture indicator  32  has been exposed to a relatively large amount of moisture. The moisture flow altering structure in region  116 A will help to distinguish the moisture level at which regions  114 A and  114 B change state (i.e., the structures of region  116 A will introduce a threshold that ensures that region  114 B will only turn red if a significantly larger amount of moisture is detected than the amount of moisture needed to turn region  114 A red. 
     In the example of  FIG. 17 , the moisture wicking behavior of layer  82  has been selectively altered in certain regions by adding one or two additional wicking layers (i.e., layer  82 A and layer  82 B). In regions where more wicking material is present, a relatively larger amount of moisture may need to be present to indicate the presence of moisture. The thicker wicking layer regions may also exhibit altered lateral moisture flow characteristics (e.g., as with regions  116 A and  116 B of  FIG. 16  as an example). 
     The cross-sectional side view of  FIG. 18  shows how moisture indicator  32  may be provided with several overlapping layers of wicking material. In the example of  FIG. 18 , wicking layer  82  covers all of the planar surface of moisture indicator  32 , wicking layer  82 A covers a portion of layer  82 , and wicking layer  82 B covers a portion of layer  82 A. This type of structure makes moisture indicator  32  less sensitive in some regions (e.g., under the thicker wicking layer regions) than in other regions. If a small amount of moisture comes into contact with moisture indicator  32 , only the thin regions of wicking material may exhibit bleed-through from the underlying dye layer. If moisture indicator  32  of  FIG. 18  is exposed to relatively large amounts of moisture, all regions of the moisture indicator would change to red to indicate the occurrence of a moisture exposure event. Intermediate levels of moisture exposure might only change the exposed portions of layers  82  and  82 A to a red color. As with the other multi-region moisture indicator arrangements, the use of multiple regions in a sensor of the type shown in  FIG. 18  may make it easier for service personnel to accurately distinguish between different levels of moisture exposure. Service personnel may, for example, simply count the number of moisture indicator regions that have changed their color from white to red to determine the amount of moisture to which device  10  was exposed. 
     As shown in  FIG. 19 , moisture indicator  32  may be provided with a wicking layer that has smooth changes in thickness. In the  FIG. 19  example, wicking layer  82  has a thickness D 1  in region  120  and a thickness D 2  in region  122 . Because thickness D 1  is greater than thickness D 2 , relatively more moisture exposure may be required to cause the color of layer  82  to change in region  120  than in region  122 . 
       FIG. 20  shows a cross-sectional view of an illustrative moisture indicator  32  in which wicking layer  82  has been selectively thinned. This type of arrangement may be used to locally sensitize moisture indicator  32  or to create moisture flow altering structures. 
     If desired, layers of material such as impermeable material or material with different moisture flow properties than wicking layer  82  may be interposed between wicking layer  82  and dye layer  80 . For example, a moisture barrier layer (e.g., a PET layer with perforations or other openings) may be interposed between dye layer  80  and wicking layer  82 . 
     A top view of an illustrative moisture barrier layer of this type is shown in  FIG. 21 . As shown in  FIG. 21 , moisture barrier layer  124  may have openings  126 . Openings  126  may all have the same size or may have different sizes. Openings  126  of  FIG. 21  are round, but this is merely illustrative. Any suitable shapes may be used for openings  126  if desired. 
     Openings  126  may be arranged within moisture barrier layer  124  so that some portions of moisture barrier layer  124  allow moisture to pass more readily than others. 
     A cross-sectional side view of a portion of a moisture indicator that has a perforated moisture barrier layer  124  of the type shown in  FIG. 21  is shown in  FIG. 22 . 
     In the example of  FIG. 22 , moisture barrier layer  124  has been interposed between dye layer  80  and wicking layer  82 . As indicated by arrows  128 , dye may bleed through openings  126 . Regions of layer  124  that are more porous (i.e., that have more openings and/or larger openings) will tend to be more sensitive to moisture than regions of layer  124  with fewer openings (and/or smaller openings). By adjusting the pattern of perforations in layer  124 , the porosity of barrier layer  124  can be adjusted and moisture indicator  32  can be provided with regions having different moisture sensitivities. If desired, moisture barrier layers such as upper moisture barrier layer  86  and lower moisture barrier layer  78  can be provided with openings (e.g., in a pattern of perforations that allow moisture to enter moisture indicator  32  in some regions more readily than in others). 
     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: 20150720
Publication Date: 20161108
Grant Date: 20161108
Priority Date: 20090526
Inventors: WANG ERIK L.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T428/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0274", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01D7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/31786", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09F3/0291", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1379", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/1379", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24942", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31786", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24612", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N31/222", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1352", "inventive": false, "first": false, "tree": "[]"}, {"code": "B32B5/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1352", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/249953", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31971", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0274", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24942", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31971", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/1303", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1303", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/249953", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24612", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01D7/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "B32B5/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/31993", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31993", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N31/222", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B5/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01D7/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09F3/0291", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1303", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01N31/222", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/13", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31971", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31993", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/1352", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/31786", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0274", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24942", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24612", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01D7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "B32B5/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/1379", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1656", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/249953", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 43220556