Abstract:
A fluidic capacitive barrier includes at least one resiliently flexible clear membrane that holds a film or thin layer of clear liquid adjacent to a capacitive touchscreen display. The clear liquid has a dielectric constant that is much less than that of water, so the liquid layer provides a capacitive barrier between the touchscreen and a surrounding body of water. Pressing a finger against the flexible membrane locally displaces some of the liquid layer, which allows the touchscreen to sense the manual touch. Thus, the fluidic capacitive barrier makes the touchscreen functional underwater. In some examples, the clear liquid is mineral oil, and the membrane is made of thermoplastic polyurethane. In some examples, the fluidic capacitive barrier is part of a hermetically sealed enclosure in which a touchscreen device can be removably installed for underwater use. In other examples, the fluidic capacitive barrier is part of a touchscreen device itself.

Description:
FIELD OF THE INVENTION 
       [0001]    The subject invention generally pertains to touchscreens and more specifically to means for rendering a touchscreen functional underwater. 
       BACKGROUND 
       [0002]    Various waterproof enclosures have been developed for using digital devices underwater. Such enclosures, however, can limit the functionality of some devices, particularly those with capacitive touchscreen displays. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a cross-sectional side view similar to  FIG. 4  but showing an example digital device installed within an example enclosure. 
           [0004]      FIG. 2  is a cross-sectional side view similar to  FIG. 2  but showing a finger actuating the touchscreen. 
           [0005]      FIG. 3  is a cross-sectional side view taken along line  3 - 3  of  FIG. 4 . 
           [0006]      FIG. 4  is a front view of  FIG. 3 . 
           [0007]      FIG. 5  is a front view showing the digital device being inserted in the enclosure. 
           [0008]      FIG. 6  is a front view similar to  FIG. 4  but showing the digital device inside the enclosure. 
           [0009]      FIG. 7  is an exploded perspective view of example membranes for the fluidic capacitive barrier shown in  FIGS. 1-6 . 
           [0010]      FIG. 8  is a front view of the membranes of  FIG. 7  but showing the membranes joined to each other. 
           [0011]      FIG. 9  is a front view similar to  FIG. 8  but showing the gap between the membranes filled with a fluid. 
           [0012]      FIG. 10  is a cross-sectional side view showing two example membranes being joined. 
           [0013]      FIG. 11  is a cross-sectional side view similar to  FIG. 10  but showing a fluid being injected between the two joined membranes. 
           [0014]      FIG. 12  is a cross-sectional side view similar to  FIG. 11  but showing a needle perforation being sealed. 
           [0015]      FIG. 13  is a cross-sectional side view similar to  FIG. 11  but showing another method for injecting fluid between the two membranes. 
           [0016]      FIG. 14  is a cross-sectional side view similar to  FIG. 13  but showing the two membranes being sealed after removal of a fluid injector&#39;s needle. 
           [0017]      FIG. 15  is a cross-sectional side view similar to  FIG. 1  but showing an example digital device with a touchscreen and an integral fluidic capacitive barrier. 
           [0018]      FIG. 16  is a cross-sectional side view similar to  FIG. 15  but showing a finger actuating the touchscreen. 
           [0019]      FIG. 17  is a cross-sectional side view similar to  FIG. 3  but showing at least one of the membranes with a coating/layer. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]      FIGS. 1-6  illustrate one example of a touchscreen system  10  that includes an example fluidic capacitive barrier  12  that allows an underlying touchscreen display  14  of a digital device  16  to be operated underwater. Digital device  16  is schematically illustrated to represent any piece of electronics. Examples of digital device  16  include, but are not limited to, a telephone, digital music player, camera, computer, tablet computer, computer monitor, personal digital assistant, video game player, PLC (programmable logic controller), GPS unit (global positioning system), IPHONE, IPOD, IPAD, etcetera. The terms, iPhone, iPod and iPad are registered trademarks of Apple, Inc. of Cupertino, Calif. Examples of digital device  16  include both portable and generally immobile devices. Some examples of a “telephone” include, but are not limited to, a cell phone, smartphone, satellite phone, etc. 
         [0021]    The term, “touchscreen” means a visual display that not only displays information (e.g., letters  18 , numbers  20 , symbols  22 , icons, maps, diagrams, photos, images, etc.) at a visual display area but also provides a means for receiving input by the visual display area being in physical contact or sufficient proximity with a manually movable external element (e.g., a human finger, stylus, pointer, wand, pen, and/or pencil, etc.). Some examples of system  10  are particularly useful when touchscreen  14  is a capacitive touchscreen display, wherein such a touchscreen is responsive to changes in capacitance in the vicinity of the touchscreen&#39;s display area. Examples of capacitive touchscreens include those that operate under known principles including, but not limited to, projected capacitance, mutual capacitance, and self-capacitance. 
         [0022]    In some examples, submerging or exposing touchscreen  14  to water adversely affects the operation of touchscreen  14  by dramatically changing the capacitance in the area where touchscreen  14  is meant to be touched for input. To overcome this problem, some examples of system  10  include various examples of a fluidic capacitive barrier overlying a touchscreen.  FIGS. 1-6  illustrate fluidic capacitive barrier  12 ,  FIGS. 15 and 16  illustrate another example fluidic capacitive barrier  12 ′, and  FIGS. 7-14  illustrate some example methods of making such fluidic capacitive barriers. 
         [0023]    In the example shown in  FIGS. 1-9 , system  10  is shown housing digital device  16  within an enclosure  24  that includes fluidic capacitive barrier  12 . Various examples of enclosure  4  are made of various example materials including, but not limited to, rigid plastic, rigid metal, pliable plastic (e.g., a bag, pouch, sack, etc.), transparent plastic, translucent plastic, opaque plastic, and various combinations thereof. Although the actual design of enclosure  24  may vary, in some examples, enclosure  24  comprises a main body  26 , a back plate  28  and a hatch  30 . Enclosure  24  defines a window area  32  ( FIG. 3 ) for functional access to touchscreen  14  of digital device  16 . 
         [0024]    Enclosure  24 , in this example, also includes various openings and/or “cutouts” to accommodate various functional elements of device  16 . For example, a hole  34  in enclosure  24  can be used for an electrical element  36  (e.g., speaker, receiver, and/or a camera) of the illustrated device  16 , a cutout  38  (e.g., a notch extending from window area  32 ) can be used for a microphone  40  and/or a pushbutton  42  (e.g., a “home button,” a rocker arm switch emulating a joystick, or a switch emulating a mouse click), and a fixed aperture  44  can be used for a camera  46  that employs one or more signals  48  and  50  (e.g., an image, a light sensing signal, range sensing signal, etc.). 
         [0025]    For the illustrated example, enclosure  24  includes a hermetically sealed electrical connection  48  for connecting a headset jack  50  of device  24  to external headphones  52 . Enclosure  24  also includes a hermetically sealed actuator  54  for actuating an on/off switch  56  of device  24 . 
         [0026]    In this example, main body  26  and back plate  28  begin as separate pieces to facilitate the manufacture of enclosure  24  by conventional plastic injection molding; however, main body  26  and back plate  28  are subsequently joined hermetically. A clear lens  58  (e.g., flat or curved, rigid or flexible) hermetically closes aperture  44 , and generally peripheral portions of fluidic capacitive barrier  12  hermetically close off window area  32 , hole  34 , and cutout  38 . In some examples, enclosure  24  is transparent and lens  58  is an integrally formed feature thereof. 
         [0027]    Hatch  30  for installing and removing device  16  from within an internal space  60  of enclosure  24  is shown in  FIGS. 5 and 6 . Hatch  30  includes a seal  62  (e.g., gasket, O-ring, press-fit, etc.) for hermetically sealing an access opening  64  ( FIG. 4 ) of enclosure  24 . When hatch  30  is closed, as shown in  FIGS. 1-4  and  6 , internal space  60  is hermetically sealed from the exterior of enclosure  24 . The term, “hermetically” means that liquid water is substantially blocked against appreciable leakage when subjected to a pressure differential of about 0.01 kg/cm. 
         [0028]    It may be worth noting that device  16  includes some appropriate conventional powered electrical circuit  66  (e.g., a microprocessor, an IC integrated circuit, circuit board, etc.) that coordinates, controls, and/or powers the operation of touchscreen  14  and the various other electrical elements of device  16 . When device  16  is disposed within internal space  60  of enclosure  24 , the device&#39;s touchscreen display  14  is generally aligned with and adjacent to window area  32  such that fluidic capacitive barrier  12  is adjacent to touchscreen  14 . 
         [0029]    In some examples, fluidic capacitive barrier  12  comprises an outer membrane  68 , an inner membrane  70  and a gap  72  therebetween. When touchscreen system  10  is immersed in water (e.g., salt water, fresh water, chlorinated water, lake, swimming pool, ocean, etc.), a fluid  74  hermetically sealed within gap  72  is such that barrier  12  reduces a detrimental capacitive effect that the surrounding water touching barrier  12  would otherwise have on the function of touchscreen  14 . Given water with a dielectric constant of about 30 to 80 (depending on its temperature and mixture with other elements), it has been discovered that examples of fluid  74  having a dielectric constant significantly less than 15 allows system  10  to function underwater in that touchscreen  14  can generally identify, for example, where a person&#39;s finger  76  is touching barrier  12  with sufficient force to bring membranes  68  and  70  in localized contact at finger  76 , as shown in  FIG. 2 . In some examples, outer membrane  68  is resiliently flexible such that after being deflected, as shown in  FIG. 2 , outer membrane  68  resiliently returns to its unstressed state shown in  FIG. 1 . In some examples, fluid  74  is hermetically sealed within gap  72 , and gap  72  is of a substantially fixed volume regardless of whether manual finger pressure is exerted against outer member  68 . In such examples, fluid  74  is completely encapsulated between membranes  68  and  70  with no need for a pump to convey fluid  74  in or out from within gap  72 . 
         [0030]    In some examples, fluid  74  includes a liquid (or some other generally incompressible fluid) so that surrounding water pressure from within a swimming pool, for example, will not likely compress fluid  74  to the extent that the water pressure alone pushes membrane  68  against membrane  70 . In some examples, fluid  74  is part of a paste or gel (e.g., a silicone gel) interposed between membranes  68  and  70 . In some examples, fluid  74  includes a mineral oil to provide fluid  74  with a dielectric constant of about 2.5 (actual value may vary depending on the concentration of mineral oil, e.g., pure mineral oil or a significant percentage of mineral oil). The term, “dielectric constant” as used in this patent refers to a material or fluid&#39;s static relative permittivity (frequency of zero). Unless otherwise specifically stated, values of dielectric constants of various fluid  74  examples mentioned herein will be with reference to the example fluid  74  being at 25 degrees Celsius. In some examples, fluid  74  includes a silicone oil to provide fluid  74  with a dielectric constant of about 2.7 (actual value may vary depending on the concentration of silicone, e.g., pure silicone or a significant percentage of silicone). In some examples, fluid  74  is a non-crystalline liquid, i.e., not a liquid crystal. 
         [0031]    In some examples, fluid  74 , inner membrane  70  and outer membrane  68  are substantially transparent. The term, “substantially transparent’ means that one can see through at some of it to view at least some of touchscreen  14 . Some examples of substantially transparent liquid and substantially transparent membranes are tinted. Some examples of substantially transparent membranes are polarized. Some examples of substantially transparent membranes include opaque areas (e.g., areas with some printing or decals thereon). 
         [0032]    In some examples, membranes  68  and  70  and/or fluid  74  are translucent or opaque. In such examples, an image is printed or projected on outer membrane  68 , wherein the printed or projected image generally coincides with and/or represents the underlying image displayed on touchscreen  14 . 
         [0033]    Although membranes  68  and  70  can be made of various materials, making membranes  68  and  70  of thermoplastic polyurethane works particularly well. Variations in membrane material thicknesses (dimensions  78  and  80 ) and variations in gap dimension  82  are possible; however, it has been discovered that a generally good design is when gap  72  (gap dimension  82 ) is greater than 0.8 mm, and membranes  68  and  70  each have a material thickness of less than 0.8 mm. In some examples, gap dimension  82  is about 2 mm, material thickness  78  of outer membrane  68  is about 0.25 to 0.41 mm, and material thickness  80  of inner membrane  70  is about 0.25 to 0.41 mm. 
         [0034]      FIGS. 7-14  show examples of various construction and assembly details. Referring to  FIGS. 7-9 , in some examples, outer membrane  68  is vacuum formed (or otherwise molded or formed) so as to create gap  72  when a peripheral flange  84  of outer membrane  68  is subsequently bonded to inner membrane  70 , wherein inner membrane  70  is relatively flat. Examples of bonding the outer membrane&#39;s flange  84  to inner membrane  70  include, but are not limited to, ultrasonic welding, heating, gluing, and/or combinations thereof. Items  86  of  FIGS. 10 and 14  schematically illustrate the methods of ultrasonic welding and heating. 
         [0035]    After membranes  68  and  70  are joined, as shown in  FIG. 8 , gap  72  is filled with fluid  74 , thereby creating fluidic capacitive barrier  12 , as shown in  FIG. 9 . One example method of filling gap  72  is shown in  FIGS. 11 and 12 .  FIG. 11  shows a pressurized fluid injector  88  with a needle nozzle  90  piercing outer membrane  68  to inject fluid  74  in gap  72 . After gap  72  is substantially filled with fluid  74  and needle  90  is removed from within gap  72 , any resulting needle perforation is sealed by heat and/or a sealant, both of which are schematically illustrated by item  92  of  FIG. 12 . 
         [0036]    One alternative to piercing outer membrane  68  is to ultrasonically weld the outer membrane&#39;s flange  84  to inner membrane  70  while needle  90  is between flange  84  and inner membrane  70 , as shown in  FIG. 13 . After injector  88  fills gap  72  with fluid  74 , needle  90  is extracted, and the area where the needle was situated is subsequently sealed, as indicated by item  86  of  FIG. 14 . In the fluid filling examples of  FIGS. 11 and 13 , gap  72  is vented in some convenient manner to allow air displaced by fluid  74  to escape from within gap  72 . Examples of such venting include, but are not limited to, needle  90  having one or more external longitudinal flutes for conveying air, having the needle perforation be larger than the outside diameter of needle  90 , and one of membranes  68  or  70  having a vent hole that is subsequently sealed shut. 
         [0037]    In another assembly method example, membranes  68  and  70  lie horizontally while being joined, wherein outer membrane  68  is underneath inner membrane  70 . Such an arrangement allows outer membrane  68  to be filled with a pool of fluid  74  prior to joining inner membrane  70  to the outer membrane&#39;s flange  84 . 
         [0038]    Once membranes  68  and  70  are joined and gap  72  is filled with fluid  74 , the resulting fluidic capacitive barrier  12  of  FIG. 9  is bonded or otherwise attached to enclosure  24 , as shown in  FIGS. 3 and 4 , whereby membranes  68  and  70  become supported by enclosure  24 . Upon attaching fluidic capacitive barrier  12  to enclosure  24 , tabs  70   a  and  70   b  of inner membrane  70  provide a beneficially thin covering for hole  34  and cutout  38 . The material thinness of tabs  70   a  and  70   b  (e.g., tabs  70   a  and  70   b  being about 0.25 to 0.41 mm thick) provide minimal interference (e.g., minimal optical interference, minimal mechanical interference, and/or minimal audio interference) with adjacent operating elements of digital device  16 , yet tabs  70   a  and  70   b  are still able to hermetically seal those areas of enclosure  24 . 
         [0039]    In some examples, a touchscreen system  94  comprises a digital device  16 ′ that includes an integral fluidic capacitive barrier  12 ′, as shown in  FIGS. 15 and 16 . In this example, touchscreen system  94  comprises digital device  16 ′ with a capacitive touchscreen display  14 ′ borne by digital device  16 ′. Barrier  12 ′ includes an outer membrane  68 ′ in proximity with the capacitive touchscreen display  14 ′. Outer membrane  68 ′ creates a gap  96  somewhere between outer membrane  68 ′ and capacitive touchscreen display  14 ′. A non-crystalline liquid (e.g., liquid  74 ) is disposed within gap  96  somewhere between outer membrane  68 ′ and capacitive touchscreen display  14 ′. The non-crystalline liquid (e.g., liquid  74 ) has a dielectric constant (i.e., relative static permittivity) of less than 15 at 25 degrees Celsius. 
         [0040]    Some examples of system  94  further include an inner membrane  70 ′ interposed between outer membrane  68 ′ and capacitive touchscreen display  14 ′, wherein gap  96  and the non-crystalline liquid (e.g., liquid  74 ) is interposed between membranes  68 ′ and  70 ′. Alternatively and/or in addition to this example, touchscreen display  14 ′ comprises a liquid crystal element  98  disposed outside of gap  96 , as shown in  FIGS. 15 and 16 . 
         [0041]    In the example shown in  FIG. 17 , at least one membrane  68  and/or  70  includes a coating or layer of material, such as layer  68   c  or  70   c  respectively. Such layers can provide one or more benefits, examples of which include, but are not limited to, reduced friction, reduced glare, improved wear resistance, scratch resistance, etc. Reduced friction, for example, may occur between layer  70   c  and a front display face  14   a  ( FIG. 1 ) of touchscreen  14 , as touchscreen  14  is inserted or removed from within enclosure  24 . Reduced friction might also occur between layer  68   c  and finger  76  sliding therealong. Example materials of layers  68   c  and/or  70   c  include, but are not limited to, polypropylene, polycarbonate, polyester, oil, silicone, powder, etc. In some examples, layers  68   c  and/or  70   c  are attached or applied to the base material of membranes  68  and  70  by various means, examples of which include, but are not limited to, co-extrusion, adhesive bonding, ultrasonic welding, spraying, dipping, etc. In some examples, layers  68   c  and/or  70   c  are simply laid against their respective membrane  68  or  70  without being positively bonded or joined thereto. 
         [0042]    Although the invention is described with respect to a preferred embodiment, modifications thereto will be apparent to those of ordinary skill in the art. The scope of the invention, therefore, is to be determined by reference to the following claims: