Patent Abstract:
An electronic device for use in a health care setting has a rigid enclosure assembly formed by a rigid shell and a rigid printed circuit board carrying circuitry for operating the device. A switch dome layer and an overlay are independently attached to the device but not to each other, whereby the overlay may be removed without disturbing the dome layer and a better tactile response is achieved.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is generally directed to an electronic device that is used in a health care setting, such as a hospital, nursing home, clinic, or similar environment. By way of example, the electronic device may be a hand-held pillow speaker kept at a patient&#39;s bedside for remotely controlling a television, room lights, or other electronic items in the room, and for communicating with nursing staff or other personnel. 
       BACKGROUND OF THE INVENTION 
       [0002]    Many electronic control and/or or communication devices, including prior art pillow speakers found in hospital rooms, have a rigid enclosure assembly for physical protection and electrical isolation. For manufacturability, it is commonplace to create the rigid enclosure assembly by providing two complementary rigid shells, and screwing, clipping or gluing the shells together with a printed circuit board (PCB) and any other electronic components inside the rigid enclosure assembly. 
         [0003]    Where the electronic device has user control buttons, these are typically incorporated into the device by a switch membrane mounted on one of the shells. A typical switch membrane either comprises the entire switch assembly and a wire harness to drive the signals to the PCB, or it includes the metal domes within its confines and adheres the domes to the PCB to create a normally open switch. 
         [0004]    Electronic devices used in health care settings are used on a daily basis, and they are cleaned and disinfected often to prevent the spread of germs. They must be reliable for patient safety reasons. Consequently, they require service and repair more frequently than electronic devices used under less demanding circumstances. 
         [0005]    Electronic devices formed according to the prior art are susceptible to damage not only from normal use, but also from liquid cleaning and disinfecting agents. Oftentimes, it is the switch membrane that is damaged, and the entire switch membrane must be removed and replaced, even though an outer graphic overlay of the switch membrane or metal switch domes of the switch membrane may be in perfect condition. 
         [0006]    Switch membranes of the prior art, wherein the switch domes are attached to the overlay material, give the electronic device a tactile performance that is less than ideal due to the resistance to movement introduced by the overlay material. 
         [0007]    What is needed is an improved electronic device assembly that is easier and less expensive to manufacture, allows for more efficient and less wasteful servicing, and responds better from a tactile standpoint to a user&#39;s pushbutton touches. 
       SUMMARY OF THE INVENTION 
       [0008]    In a first aspect of the invention, an electronic device for use in a health care setting generally comprises a rigid shell defining an interior space and an opening communicating with the interior space, and a rigid PCB fixed to the shell to cover the opening. The rigid PCB includes electronic circuitry for operation of the device. The shell and PCB cooperate with one another to form a rigid enclosure assembly for the electronic device, thereby avoiding the need for a two-piece shell to enclose a separate PCB. 
         [0009]    In a second aspect of the invention, an electronic device for use in a health care setting is improved by providing a physically separate dome layer and overlay. The dome layer may be fixed to an outward surface of the PCB and include a nonconductive sheet and a switch dome attached to the nonconductive sheet, wherein the switch dome is operable to close a switch trace on the PCB. The overlay may be arranged adjacent to the dome layer and fixed to a housing shell containing the PCB and/or to the outward surface of the printed circuit board, but the overlay is unattached to the dome layer. The overlay includes a switch graphic at a location corresponding to the switch dome. 
         [0010]    The present invention extends to methods of making and servicing electronic devices embodying one or both of the aspects summarized above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the drawings: 
           [0012]      FIG. 1  is an exploded perspective view of an electronic device formed in accordance with an embodiment of the present invention; 
           [0013]      FIG. 2  is a top plan view showing a printed circuit board, a dome layer, and an overlay of the electronic device in greater detail; 
           [0014]      FIG. 3  is a top plan view of the dome layer adhered to the printed circuit board; 
           [0015]      FIG. 4  is a plan view of an internal surface of overlay; and 
           [0016]      FIG. 5  is a top plan view of the overlay adhered to the printed circuit board overtop the dome layer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  shows, in exploded view, a pillow speaker  10  formed in accordance with an embodiment of the present invention. Pillow speaker  10  is an electronic device for use in a health care setting, such as a hospital, nursing home, clinic, or similar environment. While the present invention is described with respect to a pillow speaker, it will be understood that other types of electronic devices used in health care settings may be constructed as taught herein. Examples of other types of electronic devices to which the present invention may be applied include, without limitation, handheld pendants, bed rails, wall plates, and call cords where a user interface is required. 
         [0018]    Pillow speaker  10  generally comprises a rigid shell  12 , a rigid PCB  14 , a dome layer  16 , and an overlay  18 . Shell  12  defines an interior space  15  and an opening  30  communicating with the interior space. Shell  12  may include a plurality of fastener receptacles  20 , a cord passageway  26  through which wires may pass to reach interior space  15 , a speaker mount  28  for receiving an audio speaker (not shown), a support surface  32  for supporting PCB  14 , an inner surface  33  generally orthogonal to support surface  32  in the region of the support surface, and a rim surface  34  around opening  30 . Shell  12  may also include a retainer tab  35  protruding from rim surface  34  overtop support surface  32 . 
         [0019]    In the embodiment shown in  FIG. 1 , shell  12  is manufactured from a first shell portion  12 A and a second shell portion  12 B. The first and second shell portions  12 A,  12 B may each be molded of plastic, and then attached to one another to form rigid shell  12 . It is advantageous that the shell be free of small openings through which moisture may penetrate. Shell portions  12 A and  12 B may be ultrasonically welded together, as evidenced by weld seam  13 , to form rigid shell  12 . Alternatively, a moisture sealing adhesive may be used to bond the shell portions together. Rigid shell  12  may also be formed in unitary fashion as a single piece of molded plastic. 
         [0020]    Rigid PCB  14  is fixed to shell  12  by fasteners  24  extending through respective fastener holes  22  through PCB  14  and engaging fastener receptacles  20 . Fasteners  24  may be threaded fasteners, and fastener receptacles  20  may be internally threaded to mate with a corresponding fastener  24 . PCB  14  covers opening  30  and includes electronic circuitry (not shown) for operation of pillow speaker  10 . In accordance with a first aspect of the present invention, shell  12  and PCB  14  cooperate with one another to form a rigid enclosure assembly for pillow speaker  10 . 
         [0021]    PCB  14  includes an inward surface  38  contacting support surface  32  of shell  12 . As shown in Fig. I, support surface  32  may be recessed relative to rim surface  34 , such that a peripheral edge  40  of PCB  14  opposes inner surface  33  of the shell  12 . In this arrangement, PCB acts as a rigid member providing structural integrity to the rigid enclosure assembly. For example, if pillow speaker  10  is subjected to an impact force as may happen if pillow speaker  10  is dropped to the floor, inwardly directed force applied to the outside of shell  12  may be opposed by rigid PCB  14 . Applicants have found that a PCB thickness of 3.5 mm or greater will provide the rigid enclosure assembly with suitable structural integrity to withstand forces commonly encountered during normal use of the pillow speaker device. However, it will be understood that thickness is but one dimension of PCB  14 , and PCB&#39;s that are less than 3.5 mm in thickness may be suitable for some applications. The word “rigid,” as used herein to modify PCB, is intended to distinguish from flexible PCBs now on the market, and does not imply a minimum thickness requirement. 
         [0022]    In the embodiment of  FIG. 1 , retainer tab  35  is arranged to engage a recessed portion  37  of an outward surface  36  of PCB  14 . Retainer tab  35  and recessed portion  37  may be at corresponding longitudinal ends of shell  12  and PCB  14 , respectively, whereby the retainer tab pushes down on the end of the circuit board such that an axial tension force is created in fasteners  24  when the fasteners are tightened. 
         [0023]    Referring also now to  FIGS. 2 and 3 , it will be seen that outward surface  36  of PCB  14  may include one or more switch traces  54  associated with pushbutton control switches enabling a user to enter commands to the device. Dome layer  16  is arranged adjacent outward surface  36  of PCB  14 . Dome layer  16  includes a nonconductive sheet  42  and at least one conductive switch dome  56  attached to the sheet. Sheet  42  may be a thin polyester layer with adhesive only on its inward surface  44  ( FIG. 1 ) to adhere the sheet to outward surface  36  of PCB  14  as shown in  FIG. 3 . Each switch dome  56  is applied to adhesive surface  44  of sheet  42  and positioned to register with a corresponding switch trace  54  on the PCB, wherein the switch dome is operable to close the switch trace by applying pressure to the switch dome. 
         [0024]    Overlay  18  is arranged adjacent dome layer  16  and covers the dome layer to provide switch button embossing, switch graphics, and electrical isolation. Overlay  18  may be a polyester layer having an external surface  48  and an internal surface  50  ( FIG. 1 ). Overlay  18  may have an electrical insulation voltage rating greater than 25 kV, however this property is subject to design choice depending upon the specific application. Overlay  18  includes a switch graphic  58  on external surface  48  at a location corresponding to an associated switch dome  56  of the dome layer. The switch graphic  58  may indicate a function of the switch button to the user, and may include alphanumeric characters or a word. In a commercial embodiment of the invention, the overlay  18  is embossed in the region of each switch graphic  58  and switch dome  56  to provide a more user-friendly tactile push button. The embossing may include Braille characters to assist blind patients. 
         [0025]    As seen in  FIG. 4 , the internal surface  50  of overlay  18  may include an adhesive portion  50 A and a non-adhesive portion  50 B. Adhesive portion  50 A adheres to shell  12  and/or PCB  14 , but does not adhere to dome layer  16 . Dome layer  16  is covered by non-adhesive portion  50 B, such that overlay  18  and dome layer  16  remain unattached to one another. Accordingly, overlay  18  may be fixed to the outward surface  36  of PCB  14  by adhesive at a portion of outward surface  36  not covered by dome layer  16 . As represented in  FIG. 5 , adhesive portion  50 A may extend beyond a peripheral region of PCB  14  so that it adheres to both the peripheral region of the PCB and to the rim surface  34  of shell  12 . 
         [0026]    The present invention extends to a method of making electronic device  10 . The method generally comprises the steps of providing rigid shell  12  defining interior space  15  and opening  30  communicating with the interior space; providing rigid PCB  14  including electronic circuitry for operation of the device; and fixing the PCB to the shell such that the PCB covers the shell opening, wherein the shell and the PCB cooperate with one another to form a rigid enclosure assembly for the electronic device. A peripheral edge of the PCB may be arranged to oppose an inner surface of the shell. 
         [0027]    According to another aspect of the inventive method, PCB  14  includes outward surface  36  having switch trace  54  thereon, and the inventive method further comprises the steps of providing dome layer  16  including nonconductive sheet  42  and switch at least one dome  56  attached to the sheet; fixing dome layer  16  to outward surface  36  of PCB  14  such that the switch dome is operable to close the switch trace; providing overlay  18  overlay including at least one switch graphic  58 ; and fixing overlay  18  to at least one of the shell  12  and the outward surface  36  of PCB  14  such that the switch graphic  58  is at a location corresponding to the switch dome  56 , wherein the overlay  18  is unattached to dome layer  16 . The dome layer  16  and the overlay  18  may be fixed to the outward surface  36  of PCB  14  by adhesive at different portions of the outward surface  36 . Overlay  18  may also be fixed to shell  12  by adhesive. The steps mentioned in this paragraph also represent an improved method of making electronic device  10  for a health care setting, independently of the steps for constructing the rigid enclosure assembly described in the immediately preceding paragraph. 
         [0028]    The present invention eliminates the need for a second rigid piece to form an enclosure assembly by using the PCB for structural function in addition to electronic function. 
         [0029]    Moreover, the use of a dome layer and an overlay that are unattached to one another reduces cost, improves tactile feel of the buttons, and facilitates servicing of the device. Cost is reduced due to the fact that the dome layer  16  carries only the metal switch domes  56 , whereby the dome layer may be configured for use with a large number of corresponding overlays  18 . This reduces the number of different part numbers for manufacturing specifications. Tactile feel is improved because the user feels the entire tactile feel of the metal dome  56  itself, which was not the case with prior art switch membranes where the overlay and switch dome were physically coupled to one another. Serviceability is improved because only the overlay  18  needs to be discarded and replaced when the device is opened up, and the dome layer  16  including costly metal domes  56  can remain and be reused. 
         [0030]    With regard to serviceability, the present invention is further embodied by an improved method for servicing an electronic device of a type comprising a PCB including a switch trace, a switch dome operable to close the switch trace, and an overlay including a switch graphic at a location corresponding to the switch dome. The servicing method of the present invention comprises the steps of removing the overlay  18  from the device  10  without removing the switch dome  56  from the device  10 ; performing a service operation; and fixing a replacement overlay different from the removed overlay on the device overtop the original switch dome  56 . 
         [0031]    Modifications and other embodiments of the inventions set forth herein will be apparent to one skilled in the art to which these inventions pertain in light of teachings presented in the present specification. Therefore, the inventions are not to be limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. 
       PARTS LIST 
       [0000]    
       
           10  Electronic device (pillow speaker) 
           12  Shell 
           12 A First shell portion 
           12 B Second shell portion 
           13  Ultrasonic weld seam 
           14  Printed circuit board (PCB) 
           15  Interior space of shell 
           16  Dome layer 
           18  Overlay 
           20  Fastener receptacles 
           22  Fastener holes through PCB 
           24  Fasteners 
           26  Cord passageway 
           28  Speaker mount 
           30  Shell opening 
           32  Support surface for PCB 
           33  Inner surface of shell 
           34  Rim surface of shell 
           35  Retainer tab 
           36  Outward surface of PCB 
           36 A Portion of outward surface of PCB not covered by dome layer 
           38  Inward surface of PCB 
           40  Peripheral edge of PCB 
           42  Nonconductive sheet of dome layer 
           44  Adhesive surface of nonconductive sheet 
           46  Cut-out regions of nonconductive sheet 
           48  External surface of overlay 
           50  Internal surface of overlay 
           50 A Adhesive portion of internal surface of overlay 
           50 B Non-adhesive portion of internal surface of overlay 
           54  Switch traces on outward surface of PCB 
           56  Switch domes of dome layer 
           58  Switch graphics of overlay

Technology Classification (CPC): 8