Abstract:
Portable computer battery structures are provided. The portable computer battery structures may include a battery with a metal enclosure and a battery cable with a floating end. The battery may have six cells. Three pairs of parallel-connected cells may be connected together in series. The six cells may be substantially planar in shape. The battery may have a connector with at least five conductive pins and six recesses. The battery cable may have a cable with at least five conductive pins that mate with the five pins of the battery&#39;s connector and with six support pins that slide into the six recesses of the battery&#39;s connector. The batter connector may be formed on a printed circuit board substrate that folds over on itself.

Description:
This application is a division of patent application Ser. No. 12/340,618, filed Dec. 19, 2008, now U.S. Pat. No. 8,168,319 which claims the benefit of provisional patent application No. 61/105,039, filed Oct. 13, 2008, both 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. 12/340,618, filed Dec. 19, 2008 and provisional patent application No. 61/105,039, filed Oct. 13, 2008. 
    
    
     BACKGROUND 
     This invention relates to electronic devices and, more particularly, to battery structures for electronic devices such as portable computers. 
     Designers of portable computers are faced with competing demands. For example, it is generally desirable to reduce the weight and size of a portable computer, so that a user is not burdened by an overly heavy or overly large device. At the same time, performance characteristics such as battery life should not suffer. Often, the size of components such as a battery can be reduced, but only at the expense of reducing battery capacity and therefore battery life. For example, conventional batteries may include relatively bulky battery management circuits and relatively bulking battery enclosures or casings. 
     It would therefore be desirable to be able to provide improved batteries, battery subsystems, and battery enclosures for electronic devices such as portable computers. 
     SUMMARY 
     Portable computers with improved battery subsystems are provided. A battery may include battery cells mounted within a battery enclosure. The battery enclosure may be formed from metal. For example, the battery enclosure may be formed from a layer of sheet metal. A hem along one edge of the battery enclosure may be formed using a folded portion of the sheet metal and an adhesive. A metal end wall may be provided that occupies a small volume. A stacked mounting structure may be used to house an integral battery management unit. A window in the battery enclosure may be used to allow battery contacts to mate with a floating battery cable in a portable computer. 
     The battery may have six substantially planar cells that are connected together through a combination of series and parallel electrically connections. For example, three sets of cells may be formed by connecting together two cells in parallel for each set. The three sets of parallel-connected cells may then be connected in a series combination. With this type of arrangement, the battery may produce a ground voltage, a voltage equal to the voltage of a single cell, a voltage equal to the voltage of two cells in series, and a voltage equal to the voltage of three cells in series while each of these voltages is provided by two parallel-connected cells. 
     The battery may have a connector with at least five conductors. The five conductors may carry the ground voltage and three voltages created by the parallel-series connected battery cells as well as data signals that convey information about the battery such as the battery&#39;s charge state and temperature to an electronic device. 
     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 portable computer in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative battery showing an interior battery assembly and a battery sleeve in accordance with an embodiment of the present invention. 
         FIG. 3  is an exploded perspective view of an illustrative battery enclosure showing interior shims and spacers that may be used and showing how an end wall may be connected to one end of the enclosure in accordance with an embodiment of the present invention. 
         FIG. 4  is an exploded perspective view of an illustrative battery without its sheet metal sleeve structure in accordance with an embodiment of the present invention. 
         FIG. 5  is a perspective view of a portion of a battery sleeve hem structure that may be used in a battery enclosure in accordance with an embodiment of the present invention. 
         FIG. 6  is a perspective view of an illustrative battery connector that may be used in a portable computer in accordance with an embodiment of the present invention. 
         FIGS. 7 and 8  are perspective views of an illustrative battery management unit and an illustrative battery connector that may be used in a battery in accordance with an embodiment of the present invention. 
         FIG. 9  is a schematic diagram of an illustrative battery that may be used in a portable computer in accordance with an embodiment of the present invention. 
         FIG. 10  is a perspective view of an illustrative battery management unit and battery connector that may be formed from a folded rigid flex substrate in accordance with an embodiment of the present invention. 
         FIGS. 11A and 11B  are cross-sectional side views of a rigid flex circuit board structure of the type that may be folded over on itself and may be used as a battery management unit printed circuit board structure mounted within a battery in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention related to batteries and battery subsystems for portable computer. The battery may include battery cells mounted within a battery enclosure formed from metal. A stacked mounting structure may be used to house an integral battery management unit. The stacked mounting structure may be formed from a rigid flex circuit board structure that is folded back upon itself. A window in the battery enclosure may be used to allow battery contacts to mate with a floating battery cable in the portable computer. 
     An illustrative electronic device such as a portable computer in which a battery may be used is shown in  FIG. 1 . Portable computer  10  may be a laptop computer, as an example. As shown in  FIG. 1 , portable computer  10  may have a housing  12 . Housing  12 , which is sometimes referred to as a case, may be formed from one or more individual structures. For example, housing  12  may have a main structural support member that is formed from a solid block of machined aluminum or other suitable metal. One or more additional structures may be connected to the housing  12 . These structures may include, for example, internal frame members, external coverings such as sheets of metal, etc. Housing  12  and its associated components may, in general, be formed from any suitable materials such as such as plastic, ceramics, metal, glass, etc. An advantage of forming housing  12  at least partly from metal is that metal is durable and attractive in appearance. Metals such as aluminum may be anodized to form an insulating oxide coating. 
     Case  12  may have an upper portion  26  and a lower portion  28 . Lower portion  28  may be referred to as the base or main unit of computer  10  and may contain components such as a hard disk drive, battery, and main logic board. Upper portion  26 , which is sometimes referred to as a cover or lid, may rotate relative to lower portion  28  about rotational axis  16 . Portion  18  of computer  10  may contain a hinge and associated clutch structures and is sometimes referred to as a clutch barrel. 
     Lower housing portion  28  may have a slot such as slot  22  through which optical disks may be loaded into an optical disk drive. Lower housing portion may also have a touchpad such as touchpad  24  and may have keys  20 . If desired, additional components may be mounted to upper and lower housing portions  26  and  28 . For example, upper and lower housing portions  26  and  28  may have ports to which cables can be connected (e.g., universal serial bus ports, an Ethernet port, a Firewire port, audio jacks, card slots, etc.). Buttons and other controls may also be mounted to housing  12 . 
     If desired, upper and lower housing portions  26  and  28  may have transparent windows through which light may be emitted (e.g., from light-emitting diodes). This type of arrangement may be used, for example, to display status information to a user. Openings may also be formed in the surface of upper and lower housing portions to allow sound to pass through the walls of housing  12 . For example, openings may be formed for microphone and speaker ports. With one illustrative arrangement, speaker openings such as speaker openings  30  may be formed in lower housing portion  28  by creating an array of small openings (perforations) in the surface of housing  12 . 
     A display such as display  14  may be mounted within upper housing portion  26 . Display  14  may be, for example, a liquid crystal display (LCD), organic light emitting diode (OLED) display, or plasma display (as examples). A glass panel may be mounted in front of display  14 . The glass panel may help add structural integrity to computer  10 . For example, the glass panel may make upper housing portion  26  more rigid and may protect display  14  from damage due to contact with keys or other structures. 
     Computer  10  may have input-output components such as touch pad  24 . Touch pad  24  may include a touch sensitive surface that allows a user of computer  10  to control computer  10  using touch-based commands (gestures). A portion of touchpad  24  may be depressed by the user when the user desires to “click” on a displayed item on screen  14 . 
     A perspective exploded view of an illustrative battery that may be used in computer  10  is shown in  FIG. 2 . As shown in  FIG. 2 , battery  102  may include interior portion  40  and sleeve  32 . Interior portion  40  may include any suitable battery cells such as lithium-ion cells. Portion  40  may be inserted into sleeve  32  by sliding portion  40  in direction  44 . When inserted, plastic end cap  42  forms an end of the battery enclosure for battery  102 . 
     Battery sleeve  32  may be formed from a thin sheet of metal that has been folded to form an enclosure. The edge of the metal sheet may be sealed along hem  38  by folding the sheet back upon itself. Adhesive may also be included within the gaps along hem  38  to further seal the battery interior from its exterior. Planar shell portion  34  may have an opening  36  through which battery contacts on the lower portion of endcap  42  may be contacted. When inserted into computer  10 , these contacts may make contact with a mating male end of a battery cable. 
     When battery  102  is inserted into computer  10 , opening  36  may allow a male connector to protrude into endcap  42  and mate with a corresponding connector inside endcap  42 . For example, a connector such as connector  108  of  FIG. 6  may pass through opening  36  in sleeve  32  and couple to a connector such as connector  74  of  FIG. 4 . If desired, connector  74  may be secured to sleeve  32  and opening  36  by screws  35 . Screws  35  may pass through openings  37  in sleeve  32 . With one suitable arrangement, screws  35  may be longer than screws  39 , which may be used to secure endcap  42  to sleeve  32 , and screws  96  of  FIG. 3 , which may be used to secure end wall  94  to sleeve  32 . This type of arrangement may ensure that screws  35  are long enough to secure connector  74  to sleeve  32 . 
       FIG. 3  shows how end wall  94  may be screwed into sleeve  32  using screws  96 . Sleeve  32  may be formed from a metal such as aluminum. End wall  94  may also be formed from metal. The use of metal for enclosing battery  102  allows the structures of the battery enclosure to be compact. End wall  94  may be attached to sleeve  32  at the end of sleeve  32  opposite to that at which end cap  42  is connected. 
     Foam  92  may be mounted to the inside surface of end wall  94  to help provide shock resistance for battery  102 . Plastic tab  82  may be connected to the outer surface of sleeve  32  to help a user remove battery  102  from the interior of computer  10 . 
     Cleats  84  may be attached to the exterior of sleeve  32  in regions  86  (e.g., using adhesive). In regions  86 , the sheet metal of sleeve  32  protrudes slightly inwardly so that cleats  84  may lie flush with the surrounding portions of sleeve  32 . Smooth interior walls in sleeve  32  may facilitate insertion of interior portion  40  of battery  102  into sleeve  32 . To help ensure that the interior of sleeve  32  is smooth, even in the presence of inward protrusions under regions  86 , spacer structures such as spacer  90  and shims  88  may be mounted in the interior of sleeve  32  adjacent to protruding portions  86 . 
     An exploded view of battery  102  is shown in  FIG. 4 . As shown in  FIG. 4 , battery  102  may have lithium ion cells  52  or other suitable battery cells. Cells  52  may be held together in part by pads  62  (e.g., double-sided tape  62  may hold the upper set of battery cells to the lower set of battery cells). Cells  52  may have tabs  104  that can be spot welded to conductive portions of bus bar  56 . Bus bar  56  may be formed from polyimide with embedded conductive structures such as copper structures. Openings in the polyimide of bus bar  56  may be made to selectively expose the copper structures. Tabs  104  may be spot welded to the copper structures that are exposed in this way. Wires  64  may be electrically connected to the copper structures. The ends of wires  64  may be connected to circuitry in end cap region  42 . 
     End cap portion  42  may include end cap plastic structure  80  and battery management unit printed circuit board  76 . Battery management circuitry (e.g., one or more battery management integrated circuits) may be mounted on printed circuit board  76 . Printed circuit board  76  may be formed from a rigid flex substrate. The substrate may be folded back upon itself as shown in  FIG. 4  to form a two-layer board. The battery management circuit may be formed on the two layers of the battery management circuit substrate (E.g., the rigid flex substrate). 
     Insulating structures may be provided in battery  102  to prevent shorts. Insulating structures may include insulating patch  78 , insulating strip  54 , insulating structure  70 , and insulating sheet  46 . Insulating sheet  46  may be wrapped around cells  52  to complete the assembly of battery  102  and to enhance the structural integrity of battery  102 . Insulating structures may be formed from flame resistant fiber sheets or other suitable materials. 
     Battery management unit holder  72  may be used to support the two portions of printed circuit board  76 . Battery connector  74  may be mounted to the upper surface of printed circuit board  76 . Battery management unit wall structure  68  helps to complete the end cap structure  42  by providing interior and lower walls. Foam  66  may help provide shock resistance. A die cut insulation layer  58  may protect tabs  104  and bus bar  56  after spot welding. Die cut plastic insert  60  may help provide a smooth surface that allows interior portion  40  of battery  102  to slide into shell  32  during assembly. 
     Frame  48  may be formed from plastic. During assembly of battery  102 , cells  52  may be mounted in frame  48 . After assembly is complete and an electrically insulating fabric sheet  46  has been wrapped around frame  48  and cells  52 , interior portion  40  may be inserted into sleeve  32 . 
       FIG. 5  shows how the hem  38  of sleeve  32  may be formed by folding sheet metal  102  onto itself (i.e., onto edge  100 ) at bend  96 . Adhesive  99  may be inserted into gap  98  to help seal hem  38 . 
     A computer power cable that may be connected to battery  102  when battery  102  is inserted in computer  10  is shown in  FIG. 6 . As shown in  FIG. 6 , cable  106  may have connectors at either end such as connector  108  and connector  110 . Connector  110  may be connected to the main logic board in computer  10  or other suitable circuitry. The flat middle portion of cable  106  may be enclosed in a cover and may be placed along the interior surface of housing  12 . Connector  108  may be a male battery connector in region  112  of cable  106  that mates with connector  74  of  FIG. 4 . 
     Connector  108  may have conductive pins (contacts)  135  and pins  137  that mate with corresponding contacts in connector  74  of  FIG. 4 . Connector  108  may have support pins  134  and pins  136  that mate with corresponding recesses in connector  74  when the connectors are coupled together. Pins  134  and  136  may help to hold connectors  74  and  108  in proper alignment when connectors  74  and  108  are coupled together. 
     The position in which battery  102  is inserted into computer  10  may vary between insertion events. To accommodate this natural variation in the position of battery connector  74 , at least a portion of cable  106  may be floating (i.e., not rigidly attached to housing  12 ). This allows the end of cable  106  and connector  108  to move slightly as needed when battery  102  is connected to connector  108  by a user. 
       FIG. 7  shows an enlarged view of the printed circuit board  76  and battery connector  74  shown in  FIG. 4 . Circuit board  76  may have circuitry that controls the operation of battery  102 . Circuit board  76  may be electrically coupled to cells  52 . Circuit board  76  may also be connected to circuitry in computer  10  through cable  106 . 
     Printed circuit board  76  may include any suitable components. For example, circuit board  76  may include voltage regulator circuitry, battery monitoring circuitry that protects cells  52  during charging and discharging operations, and other suitable components. 
     Contacts  116  and  118  may be connected to battery cells  52  using wires  64 . 
     Connector  74  may have connector pins  114 A,  114 B,  114 C,  114 D, and  114 E that connect to corresponding conductive paths in cable  106  when connector  108  mates with connector  74  (e.g., when battery  102  is installed in computer  10 ). With one suitable arrangement, pin  114 A may be a ground power pin and pin  114 E may be a positive power pin. 
     If desired, one or more pins such as pins  114 B,  114 C,  114 D, and  114 E may be carry data signals between connector  74  and computer  10 . For example, pin  114 B may connect to a data signal path in cable  106  through a corresponding data signal portion of connector  108 . 
     Pins such as pins  114 B,  114 C,  114 D, and  114 E may also be redundant power signal lines or data signal lines. As an example, pin  114 C may be a redundant ground power pin and pin  114 D may be a redundant positive power pin. If desired, one or more of pins  114 A-E may be used to convey thermistor signals, clock signals, data signals, switching signals, intermediate voltage signals, and other suitable signals. 
     One or more of the pins  114 A-E may also be used to convey intermediate power supply signals between computer  10  and battery  102 . For example, pin  114 A may be a ground power pin, pin  114 C may be a first intermediate voltage pin, pin  114 D may be a second intermediate voltage pin, and pin  114 E may be a positive voltage pin. With one suitable arrangement, the first intermediate voltage corresponds to the voltage of a single cell  52 , the second intermediate voltage corresponds to the voltage of two cells  52 , and the positive voltage corresponds to the voltages of three cells  52 . Each of these voltages may be regulated by circuit board  76  and may be provided by multiple cells connected together in series and in parallel through circuit board  76 , as an example. 
     Ground springs  120  and  122  may electrically connect circuit board  76  to conductive sleeve  32 . Springs  120  and  122  may be metal spring contacts that engage with a conductive surface of sleeve  32 . With this type of arrangement, circuit board  76  may be grounded to sleeve  32  by springs  120  and  122 . 
     Pins  124 A-E may convey power and data signals between connector  74  and circuit board  76 . With one suitable arrangement, battery contacts  124 A-E are connected to electrical traces on circuit board  76 . 
     Pads  128 A and  128 B may be intermediate voltage pads that are connected to wires  62 . Pads  128 A and  128 B may also be connected to pins  114 C and  114 D, respectively. Circuit board  76  may receive intermediate voltages through pads  128 A and  128 B and may convey these voltages to computer  10  through connectors  74 ,  108  and  110  and cable  106 . 
     Holes  130  in connector  74  may receive screws  35  (shown in  FIG. 2 ). Screws  35  may hold connector  74  firmly against opening  36  of sleeve  32  so that cable connector  108  can be connected to connector  74  without putting pressure on or warping circuit board  76 . 
     Battery  102  may include temperature sensors. As shown in  FIG. 8 , circuit board  76  may include one or more pads such as pads  126 A and  126 B. Pads  126 A and  126 B may be connected through wires  64  to temperature sensors that are distributed amongst cells  52  to measure the temperature of cells  52 . The temperature sensors may be thermistors and pads  126 A and  126 B may be thermistor pads. Circuit board  76  may be able to obtain the temperature of cells  52  by measuring the resistance of the thermistors through pads  126 A and  126 B. 
     As shown in  FIG. 8 , connector  74  may include one or more side conductive contacts such as contact  132 . Contact  132  may be a grounding contact that connects a ground trace in cable  106  to a ground trace in circuit board  76 . Contact  132  may be used to convey any suitable signals such as a ground voltage, data signals, or a power supply voltage between circuit board  76  and cable  106 . 
       FIG. 8  shows how connector  74  may have two enlarged regions  140  at each end of the connector and four enlarged regions  138  between contacts  114 A-E. The enlarged regions may be enlarged relative to the portions of connector  74  corresponding to pins  114 A-E. The enlarged regions at each end of connector  74  may be somewhat larger than the enlarged regions between the pins  114 A-E. With one suitable arrangement, connector  108  may have enlarged structures at each end of the connector  108  that fit within the enlarged regions at each end of connector  74  when the connectors  74  and  108  are connected together. Connector  108  may also have somewhat smaller enlarged structures that fit within the enlarged regions of connector  74  between the pins  114 A-E. The enlarged regions of connector  74  between pins  114 A-E may also be referred to as connector receptacles. Conductive portions of connector  108  between all of the enlarged regions of connector  108  may couple with pins  114 A-E. As an example, pins  114 A-E may be receptacles that receive the conductive portions of connector  108  and that bear against the conductive portions of connector  108  when the connectors  74  and  108  are coupled together. 
     As shown in  FIG. 8 , Connector  74  may have four recesses  138  between conductive pins  114 A-E as well as two recesses  140  that are relatively larger than the recesses  138  and that are located on either side of connector  74  (e.g., adjacent to pins  114 A and  114 E). When connector  108  of  FIG. 6  is coupled to connector  74 , support pins  134  and  136  of connector  108  may slide into recesses  138  and  140 , respectively. Conductive pins  135  and  137  of connector  108  may the electrically couple to contacts  114 A-E and  132  of connector  74 . 
       FIG. 9  shows a schematic diagram of battery  102 . As shown in  FIG. 9 , cells  52  of battery  102  may form a pack  132 . Cells  52  may be connected together in any suitable configuration. For example, cells  52  may be connected together through a combination of series and parallel electrical connections. 
     As shown in  FIG. 9 , a first set of three cells  52  may be connected together in series and a second set of three cells  52  may be connected together in series. The first and second sets of cells  52  may be connected together in parallel. With this type of arrangement, battery  102  may generate multiple different voltages that can be conveyed to computer  10  through circuit board  76 . Each cell  52  may generate a particular voltage across its terminals  104  (e.g., each cell  52  may generate a voltage such as 1.5 volts, 3.7 volts, or any other suitable voltage). If desired, terminal  116  may be at a zero voltage or ground potential, terminal  128 B may be a single cell voltage above ground (e.g., 3.7 volts), terminal  128 A may be at the voltage of two cells connected in series (e.g., 7.4 volts), and terminal  118  may be at the voltage of three cells connected in series (e.g., 11.1 volts). Terminal  116  may be connected to contact  114 A and terminal  118  may be connected to contact  114 E (as an example). 
     As shown in  FIGS. 4 ,  7 , and  10 , printed circuit board  76  may be formed from a rigid flex substrate that is folded back upon itself to form a two-layer board. For example, as shown in  FIG. 10 , circuit board  76  is folded back upon itself to form a two-layer board having a first layer  77 A and a second layer  77 B. Circuit board  76  may be folded back upon itself along folds  150  (e.g., a curved portion of the rigid flex substrate of board  76 ). If desired, insulating structures such as patch  78  and structure  70  of  FIG. 4  may be located between layers  77 A and  77 B (e.g., to prevent shorts between the two layers of circuit board  76 ). 
     Battery management unit printed circuit board  76  may be formed from a rigid flex structure that is folded back upon itself to form a two-layer board. An arrangement of this type is shown in  FIGS. 11A and 11B . As shown in the cross-sectional views of  FIGS. 11A and 11B , circuit board  76  may include rigid flex structures such as rigid printed circuit board layers  152 . Rigid printed circuit board layers  152  may be formed, for example, from fiberglass-filled epoxy or other suitable rigid dielectrics. Rigid flex circuit board  76  also contains flex circuit layers such as flex circuit layers  154 . Flex circuit materials that may be used for flex circuit portion  154  include polyimide and other flexible dielectrics. Conductive traces (e.g., of copper, gold, or other suitable conductors) may be patterned within layers  152  and  154  to form desired interconnection patterns, electrical buses, etc. 
     As shown in  FIG. 11A , at least some flex circuit portions in rigid flex circuit board  76  extend between the two rigid circuit board portions (e.g., layers  77 A and  77 B of circuit board  76 ), so that some of rigid flex circuit board  76  is rigid (e.g., portions  156 ) and some of rigid flex circuit board  76  is flexible (e.g., portion  158 ). As shown in  FIG. 11B , rigid flex circuit board  76  may be folded back upon itself to form a two-layer circuit board. 
     The use of battery management unit circuit board arrangements such as the rigid flex arrangement of  FIGS. 11A and 11B  for battery management components in battery  102  may help to reduce the volume that the battery management components occupy which allows a smaller endcap  42  to be used and increased the volume of battery  102  that can be devoted to cells  52  (e.g., which can improve the energy density of battery  102  relative to conventional batteries). 
     In addition, the rigid flex arrangement may allow connector  74  to move slightly within battery  102 . This may help to accommodate natural variation in the position of battery connector  74  when battery  102  is inserted into computer  10 . For example, the rigid flex arrangement of  FIGS. 11A and 11B  can allow connector  74  to move slightly as needed when connector  74  is connected to connector  108  by a user. 
     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.