Abstract:
A battery may have a foil battery pack with leads that are coupled to a printed circuit board. Battery protection structures formed from an insulating material such as plastic may be used to protect the foil battery pack. The foil battery pack may have a rectangular shape with front and rear faces surrounded by a rectangular peripheral edge. The battery protection structures may have a ring shape that surrounds the peripheral edge while leaving the front and rear faces exposed to minimize the size of the battery protection structures. An elastomeric material may be used to form the battery protection structures. The elastomeric material may allow the battery protection structures to stretch when the battery pack expands during use. Two shots of plastic may be incorporated into the battery protection structures to provide both puncture resistance and the ability to stretch during use.

Description:
BACKGROUND 
       [0001]    This relates to electronic devices and, more particularly, to batteries for electronic devices. 
         [0002]    Electronic devices such as cellular telephones and other portable devices are often provided with batteries such as lithium ion batteries. In a typical configuration, the material layers that make up the anode and cathode for the battery are enclosed in a foil pack. 
         [0003]    In applications in which a battery for a device is a removable component, a foil battery pack is typically enclosed within a hard plastic case with metal contacts. A battery of this type will be sufficiently durable to withstand damage during normal handing, but will also be considerably more bulky than an unpackaged foil pack. 
         [0004]    Electronic devices that forgo the use of removable batteries can be fabricated more compactly, because the hard plastic case of the battery can be eliminated. Nonetheless, the mounting of foil packs directly within electronic device housings poses challenges. If care is not taken, a foil battery pack may be punctured or scratched when contacted by components within an electronic device housing such as printed circuit board shields, clips, and other components. 
         [0005]    It would therefore be desirable to be able to provide improved battery structures for an electronic device. 
       SUMMARY 
       [0006]    An electronic device may be provided with electrical components such as circuits on a printed circuit board and a battery. The components may be mounted within an electronic device housing. The battery may have a foil battery pack with leads that are coupled to the printed circuit board. 
         [0007]    Battery protection structures formed from a material such as plastic may be used to protect the foil battery pack. The foil battery pack may have a rectangular shape with front and rear faces surrounded by a rectangular peripheral edge. The battery protection structures may have a ring shape with vertical walls that surrounds the peripheral edge and protects the foil battery pack from punctures and scratches. The battery protection structures may have openings such as openings that leave the front and rear faces of the foil battery pack exposed. 
         [0008]    An elastomeric material may be used to form the battery protection structures so that the battery protection structures can stretch when the battery pack expands during use. Two shots of plastic may be incorporated into the battery protection structures to provide both puncture resistance and the ability to stretch during use. 
         [0009]    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 
         [0010]      FIG. 1  is a front perspective view of an illustrative electronic device of the type that may be provided with battery structures in accordance with an embodiment of the present invention. 
           [0011]      FIG. 2  is a cross-sectional end view of a foil battery pack in accordance with an embodiment of the present invention. 
           [0012]      FIG. 3  is a perspective view of a foil battery pack enclosed in a battery band and mounted in the interior of an electronic device housing in accordance with an embodiment of the present invention. 
           [0013]      FIG. 4  is an exploded perspective view of an elastomeric battery protection structure such as an O-shaped band with vertical walls and an associated battery and electronic device housing in accordance with an embodiment of the present invention. 
           [0014]      FIG. 5  is a side view of a portion of an illustrative battery protection structure formed from two shots of plastic in accordance with an embodiment of the present invention. 
           [0015]      FIG. 6  is a perspective view of a portion of a battery protection band or other battery protection structure showing how the structure may be provided with a notch to accommodate battery leads in accordance with an embodiment of the present invention. 
           [0016]      FIG. 7  is a cross-sectional perspective view of a battery band structure formed from multiple shots of plastic in accordance with an embodiment of the present invention. 
           [0017]      FIG. 8  is a perspective view of a ring-shaped protective battery band with a gap to accommodate battery leads in accordance with an embodiment of the present invention. 
           [0018]      FIG. 9  is a perspective view of an illustrative U-shaped protective battery band in accordance with an embodiment of the present invention. 
           [0019]      FIG. 10  is a perspective view of an illustrative battery protection structure having the shape of a pouch in accordance with an embodiment of the present invention. 
           [0020]      FIG. 11  is a perspective view of a battery protection structure configured to wrap around a central portion of a battery in accordance with an embodiment of the present invention. 
           [0021]      FIG. 12  is a perspective view of a protective battery band having a ring member that surrounds an opening that is configured to receive a battery and having ribs that bridge the opening in accordance with an embodiment of the present invention. 
           [0022]      FIG. 13  is a perspective view of an illustrative battery protection structure formed from a pouch that has an opening in one of its surfaces to receive a battery pack in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Battery packs may be formed from layers of material such as anode and cathode layers. Aluminum foil or other metal foils may be used to encapsulate the layers and thereby preventing the leakage of electrolyte. 
         [0024]    Battery packs such as foil battery packs may be fragile and subject to damage during installation and use within an electronic device. To prevent damage, battery enclosure structures may be provided. The battery enclosure structures may occupy considerably less room than a traditional battery housing, making them suitable for use in electronic devices in which space is at a premium. 
         [0025]    An illustrative electronic device of the type that may be provided with a battery is shown in  FIG. 1 . Device  10  of  FIG. 1  may be a handheld device such as a cellular telephone or media player, a tablet computer, a notebook computer, other portable computing equipment, a wearable or miniature device such as a wristwatch or pendant device, a television, a computer monitor, or other electronic equipment. 
         [0026]    As shown in  FIG. 1 , electronic device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. Configurations in which display  14  includes display layers that form liquid crystal display (LCD) pixels may sometimes be described herein as an example. This is, however, merely illustrative. Display  14  may include display pixels formed using any suitable type of display technology. 
         [0027]    Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16  and an opening such as opening  18  may be used to form a speaker port. Device configurations without openings in display  14  may also be used for device  10 . 
         [0028]    Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
         [0029]    Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
         [0030]    A cross-sectional side view of a battery that may be used in device  10  is shown in  FIG. 2 . As shown in the illustrative configuration of  FIG. 2 , battery  20  may include battery structures such as foil battery pack  22 . Foil battery pack  22  may contain rolled sheets of material that form an anode and a cathode and may contain associated electrolyte. A metal foil such as an aluminum foil or other metal foil may be used as part of the layers that form pack  22 . The metal foil may form somewhat fragile outer surfaces on pack  22 . 
         [0031]    Leads such as battery leads  24  may be coupled to foil battery structures  22 . Leads  24  may include a dielectric substrate such as substrate  26  and metal contacts  28 . Substrate  26  may be formed from a rigid printed circuit board (e.g., fiberglass-filled epoxy) or a flexible printed circuit (e.g., a sheet of polyimide or a layer of other flexible polymer). When assembled into a device, leads  24  may be electrically connected to circuitry such as processors, memory, and other electronic components  32 . As an example, components  32  may be mounted on a substrate such as printed circuit  34  having conductive traces  30  that are electrically connected to traces  28  (e.g., using solder, welds, conductive adhesive, connectors, etc.). Battery  20 , which may sometimes be referred to as a battery pack, foil battery pack, or foil pack may be based on a lithium chemistry or other suitable battery chemistry. 
         [0032]    To prevent damage such as scratches or punctures, foil battery pack  20  may be mounted within protective battery structures such as elastomeric battery protection structures  36 . Structures  36  may be formed from insulating materials such silicone, polycarbonate, or other plastics (as an example). In the illustrative configuration of  FIG. 3 , battery protection structures  36  have a ring shape with vertical walls and a rectangular interior opening that receives battery pack  20 . 
         [0033]    By using an elastomeric material to form some or all of structures  36 , structures  36  can be stretched to fit over battery pack  20  during assembly. Structures  36  may also be stretched to remove structure  36  should rework be required. By using a shape for battery protection structure  36  that does not fully enclose all six sides of battery pack (e.g., a shape that leaves the opposing upper and lower rectangular faces of rectangular battery pack  20  exposed), the amount of volume that is occupied by structures  36  can be minimized. 
         [0034]    A two-shot plastic molding process may be used in forming battery protection structures  36 . The first shot of plastic may be a harder structure such as hard plastic structures  40  (e.g., a hard plastic structure formed form a material such as polycarbonate, nylon, or other plastic that is relatively hard—at least compared to the softer portions of structures  36 ). The presence of hard plastic structures  40  may help structures  36  prevent scratches or punctures to battery pack  20 . The second shot of plastic may be a structure such as soft plastic structures  38  that is formed from silicone or other plastic that is relatively soft and stretchy. The second plastic shot may, for example, be used to provide structures  36  with an elastomeric quality that allows structures  36  to be stretched to accommodate thermal expansion of battery pack  20  during operation in device  10 . The ability of structures  36  to stretch may also facilitate attachment and removal of structures  36  from battery pack  20  during initial assembly, rework, and repair operations. 
         [0035]    Any suitable materials may be used in forming structures  40  and  38 . As examples, soft plastic structures  38  may be formed form a silicone or other elastomeric material having a Shore A hardness of about 20-40, 20-85, 30-70, less than 40, less than 50, less than 60, or less than 70 (as examples). Hard plastic structures  40  may be formed from a harder plastic than plastic structures  38 . For example, plastic structures  40  may be formed from a polymer having a Shore A hardness of about 85-100 or more than 85 (as examples). 
         [0036]    Recesses or other openings may be provided in structures  36  to accommodate leads  24  or other structures in device  10 . Leads  24  may be coupled to traces on printed circuit  34  or other circuitry in device  10 . Due to the presence of protective structures  36 , foil battery pack  20  will be protected from damage due to contact with components on printed circuit  34  or elsewhere in the interior of device housing  12 . 
         [0037]    An exploded perspective view of the components of  FIG. 3  is shown in  FIG. 4 . As shown in  FIG. 4 , electronic device housing  12  may have housing walls such as walls  12 W and a planar rear surface such as rear wall  12 R. Printed circuit  34 , battery pack  20 , and other device components may be mounted in the recessed portion formed by walls  12 W. 
         [0038]    Battery protection structures  36  of  FIG. 4  have a rectangular ring shape with vertical walls. Rectangular opening  46  in structure  36  may have a size and shape that is configured to receive rectangular battery pack  20 . Recess  42  in battery protection structures  36  may allow lead  24  to protrude through structure  36  to couple battery pack  20  to printed circuit  34  or other circuitry in electronic device  10 . 
         [0039]    Battery protection structures  36  may have hard plastic portions  40  that are surrounded with soft plastic portions  38 . Gaps such as gaps  44  in hard plastic structures  40  may be provided to divide hard plastic structures  40  into segments. As shown in  FIG. 5 , soft plastic  38  in gaps  44  can stretch outwards in directions  48  and  50  during insertion (or removal) of battery pack  20  into opening  46 . There may be any suitable number of gaps  44  along band  36 . In the example of  FIG. 4 , there are four gaps  44 , each of which is located roughly in the center of a different respective one of the four edges of rectangular ring structure  36 . Other number of gaps  44  in hard plastic  40  may be used if desired (e.g., at least one gap, at least two gaps, at least three gaps, at least four gaps, etc.). 
         [0040]      FIG. 6  shows how leads  24  (e.g., leads on a flexible printed circuit substrate or rigid printed circuit substrate) may protrude through recess  42  of battery protection structures  36 . Recess  42  may pass only through plastic structures  38  or may pass through portions of structures  38  and portions of structures  40 . 
         [0041]    A cross-sectional view of battery protection structure  36  of  FIG. 6  taken along line  52  and viewed in direction  54  is shown in  FIG. 7 . As shown in  FIG. 7 , hard plastic structures  38  may have engagement features such as protrusions  56  that are configured to engage with soft plastic structures  38 . As an example, protrusions  56  may have the shape of thin fins that extend to either side of the main band formed from hard plastic structures  40 . 
         [0042]    During a two-shot molding process, a molding tool (e.g., an injection molding tool, a compression molding tool, or other equipment for forming plastic parts) may be used to form a second shot of plastic (i.e., soft plastic structures  38 ) on top of fins  56 , thereby embedding fins  56  within soft plastic structures  38 . The presence of protrusions such as fins  56  or other engagement features on plastic structures  38  and/or  40  may help prevent structures  38  and  40  from becoming separated from each other during use. Other types of engagement features may be used to help attach structures  38  and  40  to each other (e.g., pins, holes, etc.). The configuration of  FIG. 7  is merely illustrative. 
         [0043]    Battery protection structures  36  of  FIG. 4  have a rectangular ring shape (e.g., a rectangular O-shape). If desired, battery protection structures  36  may have a rectangular ring shape ( 0 -shape) with a gap such as gap  36 G of  FIG. 8 . Structures  36  of FIG.,  8  may have a rectangular ring shape with an opening such as gap  36 G along one of its shorter sides or along one of its longer sides. Gaps such as gap  36 G may be used to accommodate leads  24 . Gaps such a gap  36 G may also facilitate assembly of battery pack  20  within battery protection structures  36 . 
         [0044]    If desired, battery protection structures  36  may have a U-shape of the type shown in  FIG. 9 . Structures such as structures  36  of  FIGS. 8 and 9  may, if desired, be formed from a single shot of plastic or may be formed from three or more shots of plastic. The configurations of  FIGS. 8 and 9  in which battery protection structures  36  have been formed from two shots of plastic is merely illustrative. 
         [0045]    In the illustrative configuration of  FIG. 10 , battery protection structures  36  have been implemented by forming an elastomeric sleeve structure having an opening along one side such as opening  58 . The elastomeric sleeve may have a shape that resembles a five-sided box formed by removing one side from a six-sided box. The sleeve structure of  FIG. 10  allows battery protection structures  36  of  FIG. 10  to serve as a pocket into which battery pack  20  may slide in direction  60 . Leads  24  may protrude from the end of battery  20  in opening  58 . 
         [0046]    Battery protection structures  36  may be formed from a single material (e.g., a hard plastic structure or soft elastomeric plastic structure) or may be formed from a combination of hard and soft plastics such as hard plastic structures  40  and soft plastic structures  38 , as shown in  FIG. 10 . Hard plastic structures  40  may be incorporated into battery protection structures  36  at locations at which there is a potential for contact with device structures and resulting damage. For example, hard plastic structures  40  may, if desired, be formed on front face  62  and opposing rear face  64  of the sleeve of  FIG. 10  in addition to or instead of incorporating hard plastic structures  40  into sidewall portions of the sleeve. 
         [0047]      FIG. 11  is a perspective view of battery protection structures  36  in an illustrative configuration in which battery protection structures  36  form a strip that is wrapped around a central portion of battery pack  20 , rather than around the peripheral edges of the rectangular outline of battery pack  20 . Battery protection structures  36  may be formed from one shot of plastic (e.g., soft plastic or hard plastic) or from two or more shots of plastic. Battery pack  20  may be mounted in battery protection structures  36  by inserting battery pack  20  into the band formed from structures  36  in direction  66  (as an example). 
         [0048]      FIG. 12  is an exploded perspective view of battery protection structures  36  and an associated battery pack (battery pack  20 ) in a configuration in which battery protection structures  36  have a rectangular ring-shaped band with an opening that is bridged by ribs  68 . Structures  36  may be formed from one type of plastic or may include soft plastic structure  38  and hard plastic structures  40 . 
         [0049]    In the illustrative configuration of  FIG. 13 , battery protection structures  36  have the shape of a pouch formed from a rectangular band-shaped ring that has front and rear faces. Rear face  72  may extend over the entire rear opening of the sidewall band that runs around the rectangular periphery of structures  36 . Front face  74  may have an opening such as opening  70  to receive battery pack  20 . Soft plastic structures  38  and/or hard plastic structures  40  may be used in forming battery protection structures  36  of  FIG. 13 . 
         [0050]    The inclusion of soft plastic structures  38  in battery protection structures  36  of  FIGS. 1-12  may allow battery pack  20  to expand when heated during use without cracking or otherwise damaging battery protection structures  36 . The walls and other members formed by hard plastic structures  40  may be sufficiently durable to withstand wear from rubbing against internal device components during use in device  10 . The use of vertical walls in structures  36  may help structures  36  and battery pack  20  fit within the potentially tight confines of electronic device  10 . 
         [0051]    Battery pack  20  is generally at least partly exposed to the environment, which may render battery pack  20  unsuitable for removable battery applications such as consumer applications in which batteries are being removed, recharged, and replaced repeatedly by a device user. Because battery pack  20  is only partly enclosed (i.e., because there is generally an opening in battery protection structures  36  that overlaps some or all of the front and rear surfaces of the battery pack or other battery pack surfaces and that therefore leaves part of the foil or other fragile material of battery pack  20  exposed), the overall volume occupied by battery protection structures  36  for non-removable battery  20  will tend to be less than the volume associated with battery enclosures for user-replaceable removable batteries. If desired, battery pack  20  and protective battery structures  36  can be installed and uninstalled occasionally (e.g., for rework in a factory or for repair). 
         [0052]    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. The foregoing embodiments may be implemented individually or in any combination.