Abstract:
A housing for a portable computing device. An upper surface of the housing facilitates access to at least one interface component. A lower surface of the housing defines a cavity to receive a battery pack. A battery pack, adapted to fit within the cavity, defines at least a portion of a first ridge for receiving an operator&#39;s finger, the first ridge having a generally curved configuration enabling said housing to be comfortably held in an operator&#39;s hand when the operator&#39;s hand is in its naturally relaxed position.

Description:
BACKGROUND OF THE INVENTION 
     Portable data terminals (PDTs) are a type of data collection devices used to collect, interpret, process, and ultimately transfer data to a larger data processing system. PDTs generally integrate a mobile computer, an alpha-numeric or numeric keypad, and at least one data acquisition device. The mobile computer portion is generally similar to known touch screen consumer oriented portable computing devices (e.g. “Pocket PCs” or “PDAs”), such as those available from PALM, HEWLETT PACKARD, and DELL. It is to be noted that PDTs differ from consumer oriented portable computing devices through the integration of more durable or “industrial” versions of their constituent components. The data acquisition device generally comprises a device that captures data from an encoded source, for example, radio frequency IDs (RFID), images, and bar codes. Additional data acquisition devices may also be provided, notably, most PDTs have an integrated keypad. A PDT may also integrate one or more wireless communication technologies, such as GSM, CDMA, 802.11 and BLUETOOTH. PDTs tend to provide improved power performance by utilizing superior batteries and power management circuits. PDTs are available from several sources, including the assignee of the present application: HAND HELD PRODUCTS. INC. 
     U.S. Pat. No. 5,801,918 issued Sep. 1, 1998, incorporated herein by reference, was the first to describe an ergonomic housing for a PDT having a finger saddle defined between the front portion and the rear portion. A finger saddle receives an operator&#39;s finger and enables the housing to be comfortably held in an operator&#39;s hand when the operator&#39;s hand is in a naturally relaxed position.  FIG. 1  is an illustration of the PDT described in the &#39;918 patent. 
     The PDT  11  has a generally rectangular housing, generally indicated as  12 , which both protects the internal component from the elements and abuse associated with use, and determines the ergonomic and functional interaction with the operator. The housing  12  has an upper surface  14  and a lower surface  16 . The upper surface  14  has a generally rectangular configuration in top plan view with a generally planar upper-most surface. 
     The upper surface  14  generally provides access to interface components of the PDT  11 , including a data acquisition initiation key  18  (e.g. scan key); a display  20  and key pad  22 . Additionally, a thumb rest  39  may be provided. 
     The lower surface  16  generally provides a finger saddle  28  and access to a battery pack  34 . The shape of the housing of the battery pack  34  is integrated with the rear of the lower surface  16 —behind the finger saddle  28 . The finger saddle  28  is formed between a front portion  24  and a rear portion  26  of the housing generally forward of the battery pack  34 . As shown, the finger saddle  28  has a generally U-shaped configuration which forms a channel across the housing  12  generally perpendicular to a longitudinal axis X of the housing, so as to separate the front portion  24  and the rear portion  26 . The finger saddle  28  also has a second U-shaped configuration parallel to the longitudinal axis of the housing  12  and conforms to the natural contour of an operator&#39;s relaxed finger. 
     The combination of the two U-shapes allows the finger saddle  28  to comfortably receive an operator&#39;s finger when the hand of the operator is in its naturally relaxed position. The aspect of the U-shaped configuration which is parallel to the longitudinal axis X of the housing  12  allows the finger saddle  28  to be tapered along the sides of the housing to provide beveled portions  35 , making the interaction between an operator&#39;s hand and the housing more comfortable. This ergonomic feature helps to reduce hand and wrist fatigue, thereby improving the overall comfort of the housing. 
     Finger saddles, in accordance with those described in the &#39;918 patent are now a common feature on a variety of PDTs. For example, the SYMBOL model MC3070 incorporates a finger saddle formed by a lower housing and a battery compartment door. However, since the inception of the finger saddle, the technology in and around PDTs has advanced significantly. For example, current PDTs incorporate larger full color displays with integrated touch screens. Also an ever increasing number of radio communication devices, such as GSM and Wi-Fi are integrated into current PDTs. It is further expected that form factors will be reduced from generation to generation. This will further increase the challenge of providing a device incorporating ergonomic features such as finger saddles. 
       FIG. 2  is a block diagram of a known PDT  200  having a more current configuration as compared with the PDT  11  shown in  FIG. 1 . A central processing unit (CPU)  202  receives data from and outputs data to other sub-systems for storage, transmission and additional processing. The CPU  202  typically comprises one or more of a number of off the shelf solutions including: embedded processors, such as an XSCALE processor available from INTEL; general purpose processors, such as a PENTIUM 4 available from INTEL; or any number of custom solutions including pre-configured field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs). Overall operation of the CPU  202  is controlled by software or firmware (typically referred to as an operating system) stored in one or more memory locations  205   n , including RAM  205   a  and FLASH memory  205   b . Examples of suitable operating systems for the PDT  200  include graphical user interfaces such as WINDOWS MOBIL, WINDOWS CE, WINDOWS XP, LINUX, PALM, and OSX. 
     In general, communication to and from the CPU  202  and among the various sub-components takes place via one or more ports or busses, including a main system bus  204 ; a plurality of Universal Asynchronous Receiver/Transmitter (UART) ports  206   n ; and a Dual Universal Asynchronous Receiver/Transmitter (DUART)  210 . 
     A variety of secondary processors may be provided to perform general and application specific functions. The example illustrated in  FIG. 2  provides three such processors: a field programmable gate array (FPGA)  212 ; an auxiliary processor  214 ; and an LCD controller  216 . The FPGA  212  may comprise any number of FPGAs including the Virtex-4 family of FPGAs available from XILINX. The FPGA  212  is used to interface with certain data acquisition system as described hereinafter. The auxiliary processor  214  may comprise any number of embedded (or general purpose) processors, including the PICmicro® family of microcontrollers available from MICROCHIP TECHNOLOGY. The auxiliary processor  214  interfaces with and controls a variety of data input devices including, for example a touch sensitive panel  222 , a keypad  224 , and a scan key or trigger  226 . The LCD controller  216  may comprise any number of available controllers including, for example, one of the available EPSON LCD controllers. As its name and connections suggest, the LCD controller  216  controls the display of images on an LCD display  220 , such as any number of displays available from SHARP. The combination of the LCD  220  and the touch sensitive panel  222  is often referred to as a “touch screen.” 
     The PDT  200  may further include a plurality of communication links such as an 802.11 communication link  240 , an IR communication link  242 , a Bluetooth communication link  244 , and a cellular communication link  246  for communication with a cellular network such as a network in accordance with the Global System for Mobile Communications (GSM). The 802.11 communication link  240  interfaces with the CPU  202  via the main system bus. The IR communication link  242 , and Bluetooth communication link  244  are connected to the CPU  202  via UART channels  206   n . The cellular communication link  246  is connected to the CPU  202  via the DUART  210 . Wired communication may be conducted via a UART, such as the UART  206   e . Each of the communication links facilitates communication with a remote device and is principally used to transfer and receive data. 
     In use, the PDT  200  may be configured to activate a data acquisition system based on the actuation of a key on the keypad  224  (including the Trigger  226 ) or a touch on the touch panel  222 . A variety of suitable data collection systems are available for integration into the PDT  200 , for example an image signal generation system  250  and an RFID reader unit  260 . The image generation system  250  operates in conjunction with the FPGA  212  to generate image frames which may either be stored as images or analyzed to extract data, such as bar code data, there from. Possible configurations of the FPGA  212  are illustrated in U.S. Pat. No. 6,947,612 incorporated herein by reference. The RFID reader unit  260  reads and extracts data from RF signals. 
     The image signal generating system  250  generally comprises a two dimensional solid state image sensor  252 , available in such technologies as CCD, CMOS, and CID, for capturing an image containing data. e.g. an, image, a bar code or a signature. Two-dimensional solid state image sensors generally have a plurality of photo sensor picture elements (“pixels”) which are formed in a pattern including a plurality of rows and a plurality of columns of pixels. The image signal generating system  250  further includes an imaging optics (not shown) focusing an image onto an active surface of the image sensor  252 . Image sensor  252  may be incorporated on an image sensor IC chip having disposed thereon image sensor control circuitry, image signal conditioning circuitry, and an analog-to-digital converter. FPGA  212  manages the capture and transfer of image data into memory  205   n . Decoding may be performed by the CPU  202  or any suitable secondary processor. Examples of suitable image signal generation system  250  include an IMAGETEAM 5x00VGA/5x00MPX imaging module of the type available from Hand Held Products, assignee of the present application. 
     One use of the image signal generating system  250  is reading and interpreting bar codes such as bar code  275  on an item  270 . In this mode, when trigger button  226  is actuated, the CPU  202  cause the appropriate control signals to be sent to the image sensor  252 . In response thereto, the image sensor  252  outputs digital image data including (hopefully) an adequate representation of the bar code symbol  275 . This data is acquired by the FPGA  212  where it is collected and subsequently transferred to memory  205   n . In accordance with a decoding program (not specifically illustrated) an attempt may be made to decode the bar code represented in the captured digital image representation. The capture and decoding of image data may occur automatically in response to a trigger signal being generated, usually by activation of the trigger  226  or a pre-selected key on keypad  224 . For example, the CPU  202  may be configured, typically through execution of a program resident in memory  205   n , to continuously capture and decode bar code symbols represented therein until either a successful decode is completed or the trigger  226  is released. The cycle may also be terminated by timing out after a number of unsuccessful decode attempts. 
     In addition to having a decode mode of operation, the image signal generation system  250  may also be configured for an image capture mode of operation. In an image capture mode of operation, an electronic image representation is captured without attempting a decode. The captured electronic image representation may be one or more of (i) stored into a designated memory location of memory  205   n , (ii) transmitted to an external spaced apart device, or (iii) displayed on LCD  220 . This mode may be used to capture, for example an image of a signature or damage to a package. 
     The RFID reader unit  260  includes an RF oscillation and receiver circuit  262  and a data decoder  264 . RFID reader unit  260  may be configured to read RF encoded data from a passive RFID tag, such as tag  277 , which may be disposed on article  270 . In such a case. RF oscillation and receiver circuit  262  transmits a carrier signal to the passive tag which in turn converts the carrier energy to voltage form and actuates a transponder (not shown) to transmit a radio signal representing the encoded tag data. RF oscillator and receiver circuit  262 , in turn, receives the radio signal from the tag and converts the data into a digital format. Data decoder  264 , typically including a low cost microcontroller IC chip, decodes the received radio signal information received by RF oscillator and receiver circuit  262  to decode the encoded identification data originally encoded into RFID tag  277 . 
     RFID reader unit  260  may, for example, operate in a selective activation mode or in a continuous read operating mode. In a selective activation mode, RFID reader unit  260  broadcasts radio signals in an attempt to activate a tag or tags in its vicinity in response to an RFID trigger signal being received. In a continuous read mode, the RF oscillation and receiver circuit  262  continuously broadcasts radio signals in an attempt to actuate a tag or tags in proximity with unit automatically, without receiving a trigger signal. PDT  200  may be configured so that the CPU  202  recognizes a trigger signal under numerous conditions, such as: (1) actuation of the trigger  226 ; (2) receipt of an RFID trigger instruction; or (3) a determination that some other predetermined condition has been satisfied. 
     In a PDT, such as PDTs  1  and  200 , ergonomics is a significant differentiator between completing products. Users of such devices may spend a significant amount of time each day with the unit in hand. With the awareness of injuries that may be associated with repetitive motion, and the desire to have a comfortable housing ergonomic considerations have become an essential factor in determining the shape of the micro computer housing. As a result, manufacturers have attempted to develop housings which combine ergonomic, functional, and aesthetic considerations. The ergonomic component of the desired micro computer has lead manufacturers to modify the shape of the housing to make it fit an operator&#39;s hand more comfortably. The present inventors have recognized a need to provide increased flexibility with the placement and shape of finger saddles to facilitate integration with current and future PDT designs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An understanding of the present invention can be gained from the following detailed description of the invention taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is an isometric view of a known PDT. 
         FIG. 2  is a block diagram of a known PDT. 
         FIG. 3   a  is an isometric view of a PDT in accordance with an embodiment of the present invention. 
         FIG. 3   b  is a rear plan view of a PDT in accordance with an embodiment of the present invention. 
         FIG. 3   c  is a side view of a PDT in accordance with an embodiment of the present invention. 
         FIG. 3   d  is an isometric view of a PDT with a battery removed. 
         FIG. 4   a  is an isometric view of a PDT and hand strap. 
         FIG. 4   b  is an isometric view of an accessory bracket. 
         FIG. 4   c  is an isometric view of an accessory bracket. 
         FIG. 4   d  is an isometric view of an alternative accessory interface as installed in a PDT. 
         FIG. 4   e  is a front view of the alternative accessory interface. 
         FIGS. 5   a  through  5   g  are side views of battery housings in accordance with embodiments of the present invention. 
         FIGS. 6   a  and  6   b  are plan views of batteries in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. It is to be noted that an element number followed by a letter generally indicates multiple occurrences of similar, either in structure or function, elements. Further, the use of an italicized “n” associated with an element number generally denotes either an unspecified instance of such element or a partial or complete grouping of such elements—the meaning of which is to be drawn from the context of such use. 
     The following description will use nomenclature associated with a PDT, however those of ordinary skill in the art will recognize that the present invention is applicable to a variety of other portable devices including bar code scanners, consumer electronics (including portable computing devices, portable radios, televisions and cell phones), and the like. It is anticipated that a variety of portable devices will benefit from the present invention, including the embodiments thereof described herein. 
       FIG. 3   a  is an isometric view of a bar shaped PDT  300  in accordance with an embodiment of the present invention. The view in  FIG. 3   a  illustrates an upperside of the PDT  300 . The PDT  300  generally comprises a lower shell  302 , an upper shell  304  and a battery pack  306 . The battery pack  306  generally comprises a housing (an upper surface of which is visible in  FIG. 3   a ); one or more cells (not illustrated); and circuitry associated with the cells (also not illustrated). The circuitry generally assists with charging and maintenance of the cells. 
     The upper shell  304  is configured to facilitate access to a keypad  322  and a combination touch panel/LCD  320  (hereinafter referred to as touch screen  320 ). Additional keys  326   n  are located on the sides of the PDT  300 . For purposes of clarity, the present description utilizes two major axis: a long axis L extending longitudinally through the PDT  300  (from a top end  301  to a bottom end  303 ) and a short axis S extending perpendicular to the long axis L and generally parallel to a plane formed by the touch screen  320 . 
       FIG. 3   b  is a rear plan view of a PDT  300  in accordance with an embodiment of the present invention. The view in  FIG. 3   b  illustrates the underside of the PDT  300  generally comprising a battery pack  306 , a scanner  310 , and an accessory interface  314  are associated with the lower shell  302 . 
     A finger saddle  303  is formed by the housing of the battery pack  306 , the lower housing  302 , and a raised portion  308  of the lower shell  302 . In particular, the battery pack  306  forms a curved ridge  306   a  defining a first curve of the finger saddle  303 . The curved ridge  306   a  supports a user&#39;s finger in a comfortable position in a relief  312 . The relief  312  forms a channel generally parallel with the short axis S of the lower shell  302  across the lower shell  302  between the curved ridge  306   a  and a ridge  308   a  formed by the raised portion  308 . The finger saddle  303  is also defined by a second curve along the long axis L of the PDT  300  (best seen in  FIG. 3   c ). The second curve is defined by the slopes of the ridges  306  and  308   a  and the relief  312 . The finger saddle  303  also defines a third curve stretching across the short axis S and perpendicular to the first and curved surfaces of the finger groove (this is also best understood with reference to  FIG. 3   c ). The third curve is formed by the surface of recess  312  curving about the longitudinal axis. 
     One of the more useful features of the finger saddle  303  is providing a surface against which the user may exert a force generally pulling the PDT  300  toward the palm of the hand. This provides a feeling of stability while providing a secure comfortable grip on the PDT  300 . While a particular shape and configuration of the finger saddle  303  has been described, it will be recognized that the finger saddle  303 , and in particular the ridge  306   a  may comprise any shape which comfortably receives and supports one or more of an operator&#39;s fingers when the hand of the operator is in its naturally relaxed position. The remaining fingers of a users hand will generally rest on the battery pack  306 . To provide further stability to a user, the battery pack  306  may be provided with one or more finger grooves, such as the grooves  306   b ,  306   c , and  306   d.    
     On the bottom end  303 , a strap retention feature  360  is provided to secure one end of a strap. The strap retention feature  360 , as illustrated, comprises a slot formed in the lower housing  302  through which one end of a strap may be passed. Alternative configurations include the securing of a metal or plastic bar within the housing. 
       FIG. 3   c  is a side view of a PDT in accordance with an embodiment of the present invention. Of note.  FIG. 3   c  illustrates the accessory interface  314  removed from the lower housing  302 . The accessory interface  314  provides a mechanical attachment point and may further provide an electrical interface for power and/or a communication. In the embodiment illustrated in  FIG. 3 , the accessory interface  314  generally comprises a column  330  extending from a base  332  and a disc  334  attached to the column  330  opposite the base  332 , wherein the disc  334  has a larger diameter than a portion of the column  330  next to the disc  334 . The base  332  mates with a reciprocal channel or groove  336  in the lower housing  302 . 
     Referring to  FIG. 3   b , the accessory interface  314  may be secured within the groove  336  using a screw  338 . This arrangement facilitates easy removal and replacement of the accessory interface  314 . Optionally, an electrical connection may be provided on the accessory interface  314 . For example, contact rings  340  and  342  may be provided on the surface of the disc  334 . Alternatively, a barrel connector may be placed inside of the column  330 . In yet another embodiment, connection pads may be located on the column  330  and/or the disc  334 . Electrical connection between the groove  336  and the accessory interface  314  may be made via any number of mechanical interfaces including, for example, pogo pins or pads. 
       FIG. 3   d  is an isometric view of a PDT with a battery removed. This figure illustrates the battery well  370  and the electrical contacts  372 . 
       FIG. 4   a  is an isometric view of a PDT  300  and hand strap  400 . The hand strap  400  includes a first end  402  provided with VELCRO and a second end  404  provided with a loop  406 . The loop  406  may be made of elastic material so as to require stretching to slip over the disk  334 . The hand strap  400  would, when secured to the strap retention feature  360  and looped around the column  330  (secured by the disc  334 ) of the accessory interface  314 , function to secure the PDT  300  to the hand of a user—when the hand is inserted between the hand strap  400  and the PDT  300 . 
     An alternative hand strap  401  is also illustrated. The alternative hand strap  401  simply comprises a band of stretchable material such as elastic, rubber or some other polymer. For example, a small diameter bungee cord may be used. The hand strap  401  would, when secured to the strap retention feature  360  and looped around the column  330  (secured by the disc  334 ) of the accessory interface  314 , function to secure the PDT  300  to the hand of a user—when the hand is inserted between the hand strap  401  and the PDT  300 . By simply pulling the hand strap off the accessory interface  314 , it becomes a loop through which a user may insert his or her hand. 
       FIG. 4   b  is an isometric view of a belt clip  410 . The belt clip  410  generally comprises a housing  412  that forms a slot  414  for receiving and securing the disk  334 . Spring biased jaws (not shown) may be provided to secure the column  330  within the slot. The jaws may be separated by a button  416  to facilitate insertion and removal of the PDT  300 . The belt clip  410  includes a spring loaded clip  416  for attaching to a users belt. 
       FIG. 4   c  is an isometric view of an accessory bracket  420 . The accessory bracket  420  may be affixed to (or integrally molded with) an accessory and functions to mechanically secure and electrically connect the accessory to the accessory interface  314  (and hence the PDT  302 ). The accessory bracket  420  generally comprises a housing  422  that forms a slot  424  for receiving and securing the disk  334 . The housing  422  also comprises contoured ribs  426   a  and  426   b  that match the contour of the lower housing  302  and provide support for the accessory bracket  420  and any associated accessory (not illustrated). The housing  422  supports one or more electrical contacts  426  for the transmission of power and/or data to and from any accessory associated with the bracket  420 . Associated accessories may include batteries, automated data collection devices, hand grips, storage devices (such as FLASH memory and optical disks), and a variety of input/output devices (e.g. display screens, keyboards, headsets, microphones, and speakers). The accessory bracket  420  may be directly connected to a housing associated with the accessories or may be remotely connected a cable. 
       FIG. 4   d  is an isometric view of an alternative accessory interface  450  as installed in a PDT  300 .  FIG. 4   e  is a front view of the alternative accessory interface  450 . The accessory interface  450  is similar to the accessory interface  314  in that it generally comprises a body  452  connected to a disc  454  via a column  456 . The accessory interface  450  also incorporates a platform  458  through which openings  460   a  and  460   b  are formed. The openings  460   a  and  460   b  are sized to permit the passage of, for example, the loop  406  of the hand strap  400 . It is to be noted that the platform  458  facilitates the uses of a belt clip  410  or an accessory bracket  420  while the hand strap  400  or  401  is installed. 
     The body  452  of the accessory interface  450  is curved to match the housing  302  and the groove  336 . The body  452   i  defines a space  462  which, when the accessory interface is secured in the groove  336 , will create a gap accommodating the loop  406 . To secure the accessory interface  450 , two columns  464   a  and  464   b  are provided. Two reciprocal indentations may be provided in the groove  336  for mating with the columns  464   a  and  464   b . A column  466  extends from the center of the body  452  into the space  462 . The column  466  accommodates a screw  468  which secures the accessory interface  450  into the groove  336 . The column  466  also secures the end of the hand strap. 
       FIGS. 5   a  through  5   f  are side views of battery housings in accordance with embodiments of the present invention. These views illustrate a variety of features that may be incorporated into battery housings in accordance with the present invention. These views also illustrate the concept that a surface of the battery housing contributes to the ergonomics of the PDT and by swapping batteries, different ergonomic configurations may be provided. 
       FIG. 5   a  is a side view of the battery pack  306 , partially illustrated in  FIGS. 3   a  through  3   c . In addition to the features discussed herein above, the illustrated configuration has one or more protrusions  520  which, when inserted, engage reciprocal reliefs in the housing  302  (not illustrated). The illustrated configuration also includes an integrally molded locking tab  522  with one or more protrusions  504  that when inserted, are biased toward and engage reciprocal reliefs (also not illustrated) in the housing  302 . 
       FIG. 5   b  is a side view of a high capacity battery pack  506 . As with the battery pack  306 , a finger saddle is formed by the battery pack  506  when inserted into the lower housing  302 . In particular, the battery pack  506  forms a curved ridge  506   a  defining a first curved shape of the finger saddle. The curved ridge  506   a  supports a user&#39;s finger in a comfortable position. The remaining fingers of a users hand will generally rest on the battery pack  506  engaging with one or more finger grooves, such as the grooves  506   b ,  506   c , and  506   d . The illustrated configuration also includes an integrally molded locking tab  522  with one or more protrusions  504  that, when inserted, are biased toward and engage reciprocal reliefs (also not illustrated) in the housing  302 . 
     Batteries such as batteries  500  and  306  may differ in shape and volume. The batteries  306  and  506  may be though of as having two portions: a mating portion  530  that is inserted into and secured by the housing  302  and a surface portion  532  that forms a gripping surface for the PDT. The mating portion  530  will remain somewhat dimensionally stable (within manufacturing tolerances) across multiple batteries (at least for any given housing). The surface portion  532  may be dimensionally modified to provide a variety of ergonomic configurations. While the illustrated examples both have been shaped to blend with the edges of the housing  302 , the surface portions of any given battery need not blend with the housing  302 . 
     In the batteries illustrated in  FIGS. 5   a  and  5   b , the upper surface of the battery pack  306  slopes from forward to back, while the upper surface of the battery pack  506  either lacks such a slope or has a differently shaped slope (in the illustrated example, the overall shape is a somewhat level convex shape. While providing different ergonomic experiences, the battery pack  506  also offers an increased internal volume facilitating the provision of larger (e.g. longer lasting) cells. 
     It is to be understood that batteries may be designed that differ in height, shape, and/or scale. In general the shape of the upper surface  520   n  may take on any desired form—examples of which are illustrated hereinafter. It is also to be understood that while the batteries  306  and  506 , as illustrated, are of a size corresponding to the battery well in the lower housing  302 , that any particular battery need not be so limited. It is further possible to use the accessory interface  314 , the accessory interface  450  or the groove  314  to assist with securing a battery having a housing that exceeds the foot print of the battery well. 
       FIGS. 5   c  through  5   g  present examples of possible alternative embodiments in which the shape of the battery housing is adjusted to satisfy different needs of different users. To achieve varying ergonomics and/or functions a user simply swaps battery packs.  FIG. 5   c  illustrates a battery housing  540  forming an opening into which a user&#39;s finger is inserted. This embodiment may prove useful in harsher environments to shield a user&#39;s finger and provide increased holdability.  FIG. 5   d  illustrates a battery housing  542  forming a pronounced finger ridge. This embodiment may be further enhanced by the addition of an optional trigger with in the ridge (please note that the trigger may be added to any disclosed embodiment).  FIG. 5   e  illustrates a battery housing  544  forming a low profile finger ridge. This embodiment may prove useful where increased holdability is desired, but size is a concern.  FIG. 5   f  illustrates a battery housing  546  that utilizes a reverse curve on the ridge that forms the finger saddle.  FIG. 5   g  illustrates a battery housing  548  forming a vertical grip. In this case a trigger  548   a  may be integrated to provide an activation signal to the attached PDT. This configuration also illustrates a battery housing exceeding the foot print of the battery well. 
       FIGS. 6   a  and  6   b  are plan views of battery packs in accordance with embodiments of the present invention.  FIG. 6   a  illustrates a battery pack  602  with a finger groove having an asymmetrical shape (in the plan view) that may prove useful for left-handed users. The standard symmetrical profile is illustrated in a dashed line to facilitate comparison. A similar, but flipped, asymmetrical profile may be useful for right handed users.  FIG. 6   b  illustrates a battery pack  604  that includes a finger dent  604   a  for receiving finger tips (those not placed within the finger saddle) of a user. 
     Although some embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.