PATENT DOCUMENT

Publication Number: US-10496211-B1
Application Number: US-201816145061-A
Country: US
Kind Code: B1

Title: Force sensing using measurements of air pressure and air flow

Abstract:
A mobile communication device includes a housing defining an interior volume and a port connecting the interior volume to an environment exterior to the device. The mobile communication device also includes a display viewable through a surface of the housing, a pressure sensor configured to measure an air pressure within the interior volume, an air flow sensor configured to measure an air flow through the port, and a processor. The processor is configured to determine an amount of force applied to the housing using a measurement of the air pressure by the pressure sensor and a measurement of the air flow by the air flow sensor.

Claims:
What is claimed is: 
     
       1. A device, comprising:
 a housing defining an interior volume and a port connecting the interior volume to an environment exterior to the device; 
 a display viewable through a surface of the housing; 
 a pressure sensor configured to measure an air pressure within the interior volume; 
 an air flow sensor configured to measure an air flow through the port; and 
 a processor configured to determine an amount of force applied to the housing using a measurement of the air pressure by the pressure sensor and a measurement of the air flow by the air flow sensor. 
 
     
     
       2. The device of  claim 1 , further comprising:
 a temperature sensor configured to measure a temperature within the interior volume; wherein: 
 the processor is further configured to determine the amount of force applied to the housing using a measurement of the temperature by the temperature sensor. 
 
     
     
       3. The device of  claim 2 , wherein:
 the temperature is a first temperature, and the temperature sensor is a first temperature sensor; 
 the device further comprises a second temperature sensor configured to measure a second temperature within the interior volume; and 
 the processor is further configured to determine the amount of force applied to the housing using a measurement of the second temperature by the second temperature sensor. 
 
     
     
       4. The device of  claim 1 , further comprising:
 an air permeable and liquid water impermeable membrane covering the port. 
 
     
     
       5. The device of  claim 1 , wherein the air flow sensor comprises a differential pressure sensor. 
     
     
       6. The device of  claim 1 , wherein the air flow sensor comprises a movable member. 
     
     
       7. The device of  claim 1 , further comprising:
 a touch sensor disposed under the surface of the housing through which the display is viewable; wherein: 
 the processor is further configured to determine the amount of force applied to the housing using a location of a touch provided by the touch sensor. 
 
     
     
       8. The device of  claim 7 , wherein:
 the processor is further configured to calibrate the air flow sensor; and 
 the processor performs the calibration when the touch sensor provides an indication of no touch on the surface of the housing through which the display is viewable. 
 
     
     
       9. The device of  claim 7 , wherein:
 the processor is configured to determine the amount of force applied to the housing in response to the touch sensor indicating a touch on the surface of the housing through which the display is viewable. 
 
     
     
       10. The device of  claim 1 , wherein the processor is configured to:
 determine whether a relationship between the measurement of the air pressure and the measurement of the air flow matches an expected air pressure to air flow relationship; and 
 transmit to a user, in response to determining the relationship between the measured air pressure and the measured air flow does not match the expected air pressure to air flow relationship, a notification indicating that the device has a damaged seal. 
 
     
     
       11. The device of  claim 1 , wherein the measurement of the air flow comprises an integration of all air flow through the port over a period of time. 
     
     
       12. A method of determining an amount of force applied to a display surface of a mobile electronic device, comprising:
 measuring an air pressure within an interior volume of the mobile electronic device; 
 measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile electronic device; and 
 determining the amount of force applied to the display surface using the measurement of the air pressure and the measurement of the air flow. 
 
     
     
       13. The method of  claim 12 , further comprising:
 measuring a temperature within the interior volume; wherein: 
 the amount of force applied to the display surface is further determined using the measurement of the temperature. 
 
     
     
       14. The method of  claim 12 , further comprising:
 monitoring the display surface for touches; wherein: 
 the amount of force applied to the display surface is determined in response to detecting a touch on the display surface. 
 
     
     
       15. The method of  claim 14 , further comprising:
 calibrating an air flow sensor, used to measure the air flow through the port, in response to detecting no touch on the display surface. 
 
     
     
       16. The method of  claim 12 , wherein measuring the air flow through the port comprises:
 integrating all air flow through the port over a period of time. 
 
     
     
       17. A method of notifying a user of a mobile communication device that the mobile communication device has a damaged seal, comprising:
 measuring an air pressure within an interior volume of the mobile communication device; 
 measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile communication device; 
 determining whether a relationship between the measured air pressure and the measured air flow matches an expected air pressure to air flow relationship; and 
 transmitting to the user, in response to determining the relationship between the measured air pressure and the measured air flow does not match the expected air pressure to air flow relationship, a notification indicating that the mobile communication device has the damaged seal. 
 
     
     
       18. The method of  claim 17 , wherein measuring the air flow through the port comprises:
 integrating all air flow through the port over a period of time. 
 
     
     
       19. The method of  claim 17 , further comprising:
 detecting a touch on a display surface of the mobile communication device; wherein: 
 the determination of whether the relationship between the measured air pressure and the measured air flow matches the expected air pressure to air flow relationship is made in response to detecting the touch on the display surface. 
 
     
     
       20. The method of  claim 17 , wherein the notification comprises a visual notification displayed on a display of the mobile communication device.

Description:
FIELD 
     The described embodiments generally relate to a device that can sense force using measurements of air pressure and air flow. More particularly, the described embodiments relate to a device that can determine an amount of force applied to a display surface using a measurement of an air pressure within an interior volume of the device, and a measurement of an air flow between the interior volume and an environment exterior to the device. 
     BACKGROUND 
     A device such as a smartphone, tablet computer, or electronic watch may include a touch sensor that indicates a location of a touch on a display surface of the device, and a force sensor that indicates an amount of force applied to the display surface by the touch. Often, the force sensor is a capacitive force sensor. A capacitive force sensor may include first and second electrodes disposed in first and second flex circuits. The flex circuits may be separated by a compressible element or gap. As the amount of force applied to the display increases, the compressible element or gap is compressed and the electrodes disposed in the flex circuits move closer to one another, thereby decreasing the capacitance between the electrodes. The flex circuits may be coupled to a processor that measures, amplifies, and digitizes the capacitance. 
     SUMMARY 
     Embodiments of the systems, devices, methods, and apparatus described in the present disclosure are directed to determining an amount of force applied to a housing or display surface of a device. The described systems, devices, methods, and apparatus employ at least a pressure sensor and an air flow sensor. The pressure sensor senses an air pressure within an interior volume of the device (e.g., an interior volume disposed under the display surface and/or under a display or a device stack disposed under the housing or display surface. The air flow sensor senses an air flow between the interior volume and an environment exterior to the device. An amount of force applied to the housing or display surface may be determined using measurements of the air pressure and the air flow. 
     In a first aspect, the present disclosure describes a device having a housing, which housing may define an interior volume and a port connecting the interior volume to an environment exterior to the device. The device may also include a display viewable through a surface of the housing, a pressure sensor configured to measure an air pressure within the interior volume, an air flow sensor configured to measure an air flow through the port, and a processor. The processor may be configured to determine an amount of force applied to the housing using a measurement of the air pressure by the pressure sensor and a measurement of the air flow by the air flow sensor. 
     In another aspect, the present disclosure describes a method of determining an amount of force applied to a display surface of a mobile electronic device. The method may include measuring an air pressure within an interior volume of the mobile electronic device; measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile electronic device; and determining the amount of force applied to the display surface using the measurement of the air pressure and the measurement of the air flow. 
     In still another aspect of the disclosure, a method of notifying a user of a mobile communication device that the mobile communication device has a damaged seal is described. The method may include measuring an air pressure within an interior volume of the mobile communication device; measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile communication device; determining whether a relationship between the measured air pressure and the measured air flow matches an expected air pressure to air flow relationship; and transmitting to the user, in response to determining the relationship between the measured air pressure and the measured air flow does not match the expected air pressure to air flow relationship, a notification indicating that the mobile communication device has the damaged seal. 
     In addition to the aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIGS. 1A-1C  show an example of an electronic device; 
         FIG. 2A  shows an example embodiment of an air flow sensor; 
         FIG. 2B  shows an enlarged view of the components positioned in or near the bypass channel of the air flow sensor described with reference to  FIG. 2A , and illustrates how the air flow sensor may detect air flow through the port; 
         FIG. 3  shows another example embodiment of an air flow sensor; 
         FIGS. 4A-4D  show various example states of a sealed but vented device (e.g., the device described with reference to  FIGS. 1A-1C ); 
         FIG. 5  illustrates an example method of determining an amount of force applied to a display surface of a mobile electronic device; 
         FIG. 6  illustrates an example method of notifying a user of a mobile communication device that the mobile communication device has a damaged seal; and 
         FIG. 7  shows a sample electrical block diagram of an electronic device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     When the interior volume of an electronic device is sealed, the air pressure within the interior volume can be used to determine (e.g., estimate) an amount of force applied to a surface of the device by a touch. The touch may be a touch with a user&#39;s finger or stylus, or a touch by other means. The surface of the device may be any surface that flexes into the interior volume, such as a display surface. One drawback to determining an amount of force applied to a surface of a device using pressure sensing alone is that it is typically not possible to completely seal a device. For example, as the air pressure exterior to the device changes due to changes in altitude, the air pressure inside a completely sealed device may cause one or more components or seals defining the interior volume to deform, break, or leak (e.g., a seal that seals the interior volume from the environment exterior to the device may pop if the interior/exterior pressure difference is too great). Most devices therefore have a port (i.e., a vent) that allows air to exit and re-enter the device. However, the rate at which air exits and re-enters the device (i.e., the vent rate) can vary in an unpredictable manor based on the construction of the device, conditions within the interior volume of the device, the environment in which the device is operated, the condition of the port that provides the venting, and/or the condition of a membrane that prevents liquid water or debris from entering the device. This can make it difficult to determine the amount of force applied to a device using nothing but a pressure measurement, and can make it particularly difficult to determine the amount of force applied to the device when the force is applied for more than an insignificant period of time or increases over time. 
     The present disclosure describes the use of an air flow sensor, in combination with a pressure sensor, to determine an amount of force applied to a surface of a device. In some embodiments, a temperature sensor or other sensors may also be used to determine an amount of force applied to a surface of a device. The pressure sensor may be used to obtain a measurement of the air pressure within an interior volume of the device. The air flow sensor may be used to obtain a measurement of the air flow between the interior volume and an environment exterior to the device, and in some cases may integrate all air flow through a port (into and out of the interior volume) over a period of time. Integrating all air flow through the port over a period of time enables a size of the interior volume (or a change of size of the interior volume), as affected by an applied force, to be determined. The temperature sensor may be used to obtain a measurement of the temperature within the interior volume. In some embodiments, a spring constant for the surface to which the force is applied (e.g., a display surface of the device) may be obtained based on a location of a touch on the surface. The location of a touch may be determined from an output of a touch sensor of the device. 
     In some embodiments, a measurement of air pressure, a measurement of air flow, or a relationship between measurements of air pressure and air flow, may be used to determine whether a device has a damaged seal, enabling the device to notify a user of the device that the device has a damaged seal (or take other actions). 
     Force sensing using an air pressure sensor and an air flow sensor may provide force sensing at a lower cost compared to force sensing solutions that rely on capacitive or resistive force sensors. 
     These and other embodiments are described with reference to  FIGS. 1A-7 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
     Directional terminology, such as “top”, “bottom”, “upper”, “lower”, “front”, “back”, “over”, “under”, “above”, “below”, “left”, “right”, etc. is used with reference to the orientation of some of the components in some of the figures described below. Because components in various embodiments can be positioned in a number of different orientations, directional terminology is used for purposes of illustration only and is in no way limiting. The directional terminology is intended to be construed broadly, and therefore should not be interpreted to preclude components being oriented in different ways. The use of alternative terminology, such as “or”, is intended to indicate different combinations of the alternative elements. For example, A or B is intended to include, A, or B, or A and B. 
       FIGS. 1A-1C  show an example of an electronic device or simply “device”  100 . The device&#39;s dimensions and form factor, including the ratio of the length of its long sides to the length of its short sides, suggest that the device  100  is a mobile phone (e.g., a smartphone). However, the device&#39;s dimensions and form factor are arbitrarily chosen, and the device  100  could alternatively be any portable electronic device including, for example, a mobile phone, tablet computer, portable computer, portable music player, health monitoring device, portable terminal, or other portable or mobile device.  FIG. 1A  shows a front isometric view of the device  100 ;  FIG. 1B  shows a rear isometric view of the device  100 ; and  FIG. 1C  shows a cross-section of the device  100 . The device  100  may include a housing  102  that at least partially surrounds a display  104 . The housing  102  may include or support a front cover  106  or a rear cover  108 . The front cover  106  may be positioned over the display  104 , and may provide a window through which the display  104  may be viewed. In some embodiments, the display  104  may be attached to (or abut) the housing  102  and/or the front cover  106 . 
     As shown in  FIGS. 1A &amp; 1B , the device  100  may include various other components. For example, the front of the device  100  may include one or more front-facing cameras  110 , speakers  112 , microphones, or other components  114  (e.g., audio, imaging, or sensing components) that are configured to transmit or receive signals to/from the device  100 . In some cases, a front-facing camera  110 , alone or in combination with other sensors, may be configured to operate as a bio-authentication or facial recognition sensor. The device  100  may also include various input devices, including a mechanical or virtual button  116 , which may be accessible from the front surface (or display surface) of the device  100 . The device  100  may also include buttons or other input devices positioned along a sidewall  118  of the housing  102  and/or on a rear surface of the device  100 . For example, a volume button or multipurpose button  120  may be positioned along the sidewall  118 , and in some cases may extend through an aperture in the sidewall  118 . By way of example, the rear surface of the device  100  is shown to include a rear-facing camera  122  or other optical sensor (see,  FIG. 1B ). A flash or light source may also be positioned along the rear of the device  100  (e.g., near the camera  122 ). In some cases, the rear surface of the device  100  may include multiple rear-facing cameras. 
     The display  104  may include one or more display elements including, for example, a light-emitting display (LED), organic light-emitting display (OLED), liquid crystal display (LCD), electroluminescent display (EL), or other type of display element. The display  104  may also include, or be associated with, one or more touch and/or force sensors that are configured to detect a touch and/or a force applied to a surface of the front cover  106 . 
     The various components of the housing  102  may be formed from the same or different materials. For example, the sidewall  118  may be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastics), ceramics, or composites (e.g., carbon fiber). In some cases, the sidewall  118  may be a multi-segment sidewall including a set of antennas. The antennas may form structural components of the sidewall  118 . The antennas may be structurally coupled (to one another or to other components) and electrically isolated (from each other or from other components) by one or more non-conductive segments of the sidewall  118 . The front cover  106  may be formed, for example, using one or more of a glass, a crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that enables a user to view the display  104  through the front cover  106 . In some cases, a portion of the front cover  106  (e.g., a perimeter portion of the front cover) may be coated with an opaque ink to obscure components included within the housing  102 . The rear cover  108  may be formed using the same material(s) that are used to form the sidewall  118  or the front cover  106 . In some cases, the rear cover  108  may be part of a monolithic element that also forms the sidewall  118  (or in cases where the sidewall  118  is a multi-segment sidewall, those portions of the sidewall  118  that are non-conductive). in still other embodiments, all of the exterior components of the housing  102  may all be formed from a transparent material, and components within the device  100  may or may not be obscured by an opaque ink or opaque structure within the housing  102 . 
       FIG. 1C  depicts a cross-section of the device  100  shown in  FIGS. 1A and 1B . As shown in  FIG. 1C , the rear cover  108  may be a discrete or separate component that is attached to the sidewall  118 . In other cases, the rear cover  108  may be integrally formed with part or all of the sidewall  118 . 
     The front cover  106  may be mounted to the sidewall  118  to cover an opening defined by the sidewall  118  (i.e., an opening into an interior volume  124  in which various electronic components of the device  100 , including the display  104 , may be positioned). The front cover  106  may be mounted to the sidewall  118  using fasteners, adhesives, seals, or other components. By way of example, the front cover  106  is shown to be mounted to the sidewall  118  by a gasket  126  that separates the front cover  106  from the sidewall  118 . A first adhesive may be disposed between the gasket  126  and the sidewall  118 , and a second adhesive (which may have the same or different composition as the first adhesive) may be disposed between the front cover  106  and the gasket  126 . The front cover  106  may be at least partially surrounded by the sidewall  118 , as shown, or attached to an upper surface of the sidewall  118  such that the front cover  106  sits above the sidewall  118 . 
     The interior volume  124  may be further defined by the rear cover  108 , or by a support plate or other housing component positioned between the front cover  106  and the rear cover  108 . In some embodiments, a support plate may be coupled to the sidewall  118 , or to components thereof, between the front cover  106  and the rear cover  108 . 
     In some embodiments, a display stack or device stack (hereafter referred to as a “stack”  138 ) including the display  104  may be attached to an interior surface of the front cover  106  and extend into the interior volume  124 . In some cases, the stack  138  may include a touch sensor (e.g., a grid of capacitive touch sensing elements formed at the intersections of different electrodes in orthogonal sets of electrodes), or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensor (or part of a touch sensing system) may be configured to detect a touch applied to an outer surface of the front cover  106  (e.g., to a display surface of the device  100 ). In some cases, a force sensor (or part of a force sensing system) may be positioned within the interior volume  124  below and/or to the side of the display  104 . A portion of the force sensor (e.g., a pressure sensor  128 ) may be positioned within the interior volume  124  and configured to measure an air pressure within the interior volume  124 , and another portion of the force sensor (e.g., an air flow sensor  130 ) may be positioned within the interior volume  124 , adjacent a port  132  (or vent) within the housing  102 ), and configured to measure an air flow  134  through the port  132  (e.g., an integration of all air flow through the port  132  (into and out of the interior volume  124 ) over a period of time). The port  132  may be a single aperture or multiple aperture port. By way of example,  FIG. 1C  shows a port  132  within the sidewall  118 . The port  132  may allow air trapped within the interior volume  124  to escape and return (exit and re-enter) the interior volume  124 . Air may escape, for example, when a user presses on the front cover  106  or elsewhere on the device  100 , or when the device  100  is transported to an environment having an air pressure that differs from the air pressure within the interior volume  124 . In some embodiments, the air flow sensor  130  may be positioned fully or partially within the port  132 . In some embodiments, the force sensor may include only the pressure sensor  128  or only the air flow sensor  130 . 
     The touch sensor may include an array of electrodes that are configured to detect a location of a touch on the front cover  106  using a capacitive, resistive, strain-based, or other sensing configuration. The touch sensor may include, for example, a set of capacitive touch sensing elements, a set of resistive touch sensing elements, or a set of ultrasonic touch sensing elements. When a user of the device touches the front cover  106 , the touch sensor (or touch sensing system) may detect one or more touches on the front cover  106  and determine locations of the touches on the front cover  106 . The touches may include, for example, touches by a user&#39;s finger or stylus. When a user of the device  100  touches or presses on the front cover  106  (e.g., touches or applies a force to the front cover  106 ), the force sensor may determine an amount of force applied to the front cover  106  by the user. In some embodiments, a force determination operation of the force sensor (or force sensing system) may be triggered in response to the touch sensor detecting a touch on the front cover  106  (or a location of a touch or touch centroid on the front cover  106 ). 
     The pressure sensor  128  may include a single pressure sensor, or a set of multiple pressure sensors providing measurements of air pressure from which an air pressure of the interior volume  124  may be determined. The pressure sensor(s)  128  may be opportunistically positioned within the interior volume  124  or positioned within portions of the interior volume  124  where air pressure is expected to change most significantly in response to a force applied to the front cover  106 . In some cases, the pressure sensor  128  may include a thin film which forms part of a capacitive sensor or a resistive sensor (e.g., a strain gauge). In some embodiments, the force sensor may include, or receive measurements from, one or more temperature sensors  136  that are configured to measure a temperature within the interior volume  124 . Similarly to the pressure sensor(s), the temperature sensor(s)  136  may be opportunistically or purposefully positioned within the interior volume  124 . In some cases, a temperature measurement acquired from a single temperature sensor  136  may adequately reflect the temperature within the interior volume  124 . In other cases, temperature measurements from a set of multiple temperature sensors  136  may be combined to form an average (or mean) temperature, or a weighted average temperature (e.g., a temperature in which the temperature measurements made by one or more temperature sensors  136  are weighted more heavily than the temperature measurements made by one or more other temperature sensors  136 ). In some embodiments, the force sensor may use the measurement(s) of temperature made by the temperature sensor(s)  136 , in combination with the measurements made by the pressure sensor(s)  128  and the air flow sensor  130 , to determine the amount of force applied to the housing  102 . The temperature sensor(s) may be positioned to generally measure the temperature within the interior volume  124 , or to measure the temperature of heat sources (e.g., a processor) that affect the temperature within the interior volume  124 . 
     A processor may be disposed within the interior volume  124 , and in some cases may be part of (or coupled to) the stack  138 . The processor may be configured to operate the touch sensor and/or force sensor. For example, the processor may be configured to receive, evaluate, propagate, or respond to signals obtained from the touch sensor or force sensor. The processor may also be configured to operate other components of the device  100 , such as the display  104 . The processor may include, for example, a single discrete processor, a distributed processor having multiple discrete components, or a set of processors, controllers, and/or other circuits that perform one or more processing functions. 
     The force sensor described with reference to  FIGS. 1A-1C  may determine an amount of force applied to the front cover  106  using a measurement of air pressure made by the pressure sensor  128  and a measurement of air flow made by the air flow sensor  130 . In some cases, the amount of force applied to the front cover  106  may be further determined using a measurement of temperature made by the temperature sensor(s)  136 . The amount of force applied to the front cover  106  may also be determined using a spring constant of the front cover  106 . The spring constant may depend on the degree to which the front cover  106  flexes (which may be based on the material and/or dimensions of the front cover  106 , as well as the items that are attached to the front cover  106 ), and the manner of attachment of the front cover  106  to the sidewall  118 . In some cases, the spring constant may be a single value. In other cases, the spring constant may be determined based on a location or centroid of a touch detected on the front cover  106 . For example, different touch locations or touch zones may be mapped to different spring constants, which different spring constants may reflect different behaviors of the front cover  106  under forces applied at different locations on the front cover  106  (e.g., the front cover  106  may behave differently when pressed near its center instead of near its perimeter). 
     In some embodiments, the amount of force applied to the front cover  106  or (display surface) at time t (i.e., F(t)) may be determined using the equation:
 
 F ( t )=( P   inside ( t )− P   outside ) A+C   1 ( V   0   −V ( t ))
 
which represents the sum of vertical forces on the front cover  106  from mechanical bending (linearized) and the resultant change in pressure within the interior volume  124 . In the above equation, P inside  (t) is a measurement of the air pressure within the interior volume  124 , by the pressure sensor  128 ; P outside  is a measurement of the air pressure external to the device  100  (e.g., the air pressure of the environment exterior to the device  100 ); A is the effective piston area of the front cover  106 ; C 1  is the afore-mentioned spring constant of the front cover  106 ; V 0  is the size of the interior volume  124  when no force is applied to the front cover  106 ; and V(t) is the size of the interior volume (which instantaneous volume may decrease in size as an amount of force applied to the front cover  106  increases). The value of P outside  may be estimated for a particular altitude, obtained from weather information, or measured by a pressure sensor (e.g., a barometric pressure sensor) positioned in or adjacent a second port of the device  100 .
 
     The ideal gas equation states that:
 
 P ( t ) V ( t )=( t ) RT ( t )
 
     where P(t) is the pressure within the interior volume  124 ; V(t) is the size of the interior volume  124 ; N(t) is a number of moles of gas (e.g., air) within the interior volume  124 ; R is a gas constant; and T(t) is a measurement of the temperature within the interior volume  124 , as obtained by the temperature sensor(s)  136 . Solving for volume yields the equation: 
     
       
         
           
             
               V 
               ⁡ 
               
                 ( 
                 t 
                 ) 
               
             
             = 
             
               
                 
                   N 
                   ⁡ 
                   
                     ( 
                     t 
                     ) 
                   
                 
                 ⁢ 
                 R 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   T 
                   ⁡ 
                   
                     ( 
                     t 
                     ) 
                   
                 
               
               
                 P 
                 ⁡ 
                 
                   ( 
                   t 
                   ) 
                 
               
             
           
         
       
     
     The number of moles of gas inside the interior volume  124  can be determined as a starting number of moles minus a number of moles measured by the air flow sensor  130 : 
               N   ⁡     (   t   )       =       N   0     -     (       C   2     ⁢     ∫       M   ⁡     (   t   )       ⁢   d   ⁢           ⁢   t         )             
where N 0  is the starting number of moles; C 2  is a constant that converts the output of the air flow sensor  130  to moles; and M(t) is a measurement of air flow  134  by the air flow sensor  130  (e.g., an integration of all air flow through the port  132  (into and out of the interior volume  124 ) over a period of time).
 
     Substituting the equation for N(t) into the equation for V(t), and substituting the equation for V(t) into the equation for F(t), yields the equation: 
     
       
         
           
             
               F 
               ⁡ 
               
                 ( 
                 t 
                 ) 
               
             
             = 
             
               
                 
                   ( 
                   
                     
                       
                         P 
                         inside 
                       
                       ⁡ 
                       
                         ( 
                         t 
                         ) 
                       
                     
                     - 
                     
                       P 
                       outside 
                     
                   
                   ) 
                 
                 ⁢ 
                 A 
               
               + 
               
                 
                   C 
                   1 
                 
                 ⁢ 
                 
                   { 
                   
                     
                       V 
                       0 
                     
                     - 
                     
                       
                         
                           R 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           
                             T 
                             ⁡ 
                             
                               ( 
                               t 
                               ) 
                             
                           
                         
                         
                           
                             P 
                             inside 
                           
                           ⁡ 
                           
                             ( 
                             t 
                             ) 
                           
                         
                       
                       ⁢ 
                       
                         ( 
                         
                           
                             N 
                             0 
                           
                           - 
                           
                             
                               C 
                               2 
                             
                             ⁢ 
                             
                               ∫ 
                               
                                 
                                   M 
                                   ⁡ 
                                   
                                     ( 
                                     t 
                                     ) 
                                   
                                 
                                 ⁢ 
                                 d 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 t 
                               
                             
                           
                         
                         ) 
                       
                     
                   
                   } 
                 
               
             
           
         
       
     
     In embodiments of the device  100  that do not include the temperature sensor(s)  136 , the temperature of the interior volume  124  may be estimated based on one or more parameters, such as the number or type of components of the device  100  that are powered, the time that the components have been powered, the ambient temperature of the device  100  (i.e., the temperature of the environment exterior to the device  100 ), and/or the number of moles of air that have been recently expunged from and/or taken into the device  100  through the port  132 . 
     Turning now to  FIG. 2A , there is shown an example embodiment of an air flow sensor  200 , which in some cases may be the air flow sensor  130  described with reference to  FIG. 1C . In this example, the air flow sensor  200  is positioned adjacent an end of the port  132  described with reference to  FIG. 1C  (although the air flow sensor  200  could alternatively be positioned partially or wholly within the port  132 ). The air flow sensor  200  may include a main channel  202  and a bypass channel  204 . A heater  206  may be positioned in or near the bypass channel  204 , to heat air flowing through the bypass channel  204 . A first temperature sensor  208  may be positioned in or near the bypass channel  204 , closer to the interior volume  124 , and a second temperature sensor  210  may be positioned in or near the bypass channel  204 , closer to an environment exterior to the device  100 . 
     An air permeable and liquid water impermeable membrane  212  may cover the port  132 , and in some cases may be mounted adjacent an innermost end of the port  132 . Alternatively, the membrane  212  may be positioned within the port  132 , or adjacent an outermost end of the port  132 . In some embodiments, the membrane  212  may be a hydrophobic membrane with small pores that allow air molecules, but not liquid water molecules, to pass. 
       FIG. 2B  shows an enlarged view of the components positioned in or near the bypass channel  204  of the air flow sensor  200  described with reference to  FIG. 2A , and illustrates how the air flow sensor  200  may detect air flow  134  through the port  132  shown in  FIG. 2A . As shown, the heater  206  (e.g., a resistive filament that generates heat in response to a current applied to the filament) may heat at least a portion  214  of the air in the bypass channel  204 , between the first and second temperature sensors  208 ,  210 . When air exits the interior volume  124 , in the direction shown, the air  214  heated by the heater  206  moves toward the second temperature sensor  210  and increases the temperature registered by the second temperature sensor  219  with respect to the temperature registered by the first temperature sensor  208 . When air re-enters the interior volume  124 , opposite the direction shown, the air heated by the heater  206  moves toward the first temperature sensor  208  and increases the temperature registered by the first temperature sensor  208  with respect to the temperature registered by the second temperature sensor  210 . The amount and sign of the difference between the temperatures measured by the first and second temperature sensors  208 ,  210  can be used to determine a direction of air flow  134  and amount of air flow  134 . The air flow sensor  200  can be considered a type of differential pressure sensor. 
     The air flow sensor  200  described with reference to  FIGS. 2A &amp; 2B , or a processor or other circuit connected to the air flow sensor  200 , may integrate all air flow through the port  132  over a period of time, thereby enabling a determination of the number of moles of air that are within the interior volume  124  at any given point in time. 
     In some embodiments, a touch sensor (e.g., the touch sensor described with reference to  FIG. 1C ) may trigger a processor (e.g., the processor described with reference to  FIG. 1C ) to determine an amount of force applied to a surface of a housing through which a display is viewable (e.g., a surface of the front cover  106 ). For example, the processor may determine the amount of force in response to receiving, from the touch sensor, an indication of a touch on the surface. In some embodiments, the processor may determine the amount of force in response to receiving, from the touch sensor, an indication of a touch location (i.e., a location of a touch) or a touch centroid. The touch location may not only trigger a determination of the amount of force, but may also be used to identify a spring constant (e.g., the afore-mentioned constant C 1 ) that is to be used when determining the amount of force applied by a touch at the touch location. 
     In some embodiments, a processor may calibrate a force sensor that includes a pressure sensor and an air flow sensor. The calibration may be performed at a time when a touch sensor provides an indication of “no touch” on a surface of a housing through which a display is viewable. For example, the processor may calibrate values of V 0  and ∫M(t)dt when the touch sensor indicates a no touch condition. 
       FIG. 3  shows another example embodiment of an air flow sensor  300 , which in some cases may be the air flow sensor  130  described with reference to  FIG. 1C . In this example, the air flow sensor  300  is positioned partially or wholly within the port  132  (although the air flow sensor  300  may be alternatively positioned adjacent an end of the port  132 ). The air flow sensor  300  may include a movable member  302  (e.g., a flap connected to a pivot) that moves one way or another, and to a greater or lesser extent, in response to a direction and quantity of air flow  134  through the port  132 . 
       FIGS. 4A-4D  show various example states of a sealed but vented device (e.g., the device  100  described with reference to  FIGS. 1A-1C ). The sealed but vented device  100  allows air within the interior volume  124  to escape and re-enter the device  100  through the port  132 , but restricts the flow of air through the port  132  such that the air within the interior volume  124  acts as an air spring or piston that initially opposes a force applied to a display surface or front cover  106  of the device  100 .  FIG. 4A  shows the device  100  in a steady state when a user is not touching the display surface or front cover  106 .  FIG. 4B  shows the device  100  after a user has touched and begins to press on the display surface with a force F(t). As shown in  FIG. 4B , the air within the interior volume  124  initially acts as an air spring that opposes the force F(t), but begins to exit the interior volume  124  through the port  132  (e.g., as air flow  134 ).  FIG. 4C  shows the device after the force F(t) has reached an arbitrary maximum and the air pressure within the interior volume  124  has reached a steady state (e.g., as a result of the force applied to the display surface being balanced by the increased air pressure within the interior volume  124  and the spring force of the front cover  106 ). In the state shown in  FIG. 4C , air may cease to flow through the port  132 .  FIG. 4D  shows the device  100  after the user has ceased applying the force F(t). As the device  100  returns to a steady state with no force being applied to the display surface, air may re-enter the interior volume  124  through the port  132  (e.g., as air flow  134 ). 
     Various operations may be performed, and determinations made, in the various states of the device  100  shown in  FIGS. 4A-4D . For example, in the state shown in  FIG. 4A , various aspects of the device&#39;s force sensor may be calibrated. In some cases, the calibrations may be performed in response to a touch sensor of the device  100  providing an indication of no touch on the display surface or front cover  106 . In some cases, the calibrations may be performed in response to the air flow sensor  130  indicating no air flow for a period of time (or an integrated air flow of zero), and the pressure sensor  128  indicating a pressure that is equal to (or about equal to) an expected rest pressure within the interior volume  124 . The calibrations may include, for example, setting the air flow integrated by the air flow sensor  130  to zero or setting an air pressure measured by the pressure sensor  128  to a resting air pressure of the interior volume  124 . A determined force F(t) at the resting air pressure may also be set to zero. 
     In the state shown in  FIG. 4B , the pressure sensor  128  may be used to obtain one or more measurements of air pressure within the interior volume  124 , and the air flow sensor  130  may be used to obtain one or more instantaneous air flow measurements or determine an integration of all air flow through the port  132  up to the time the air pressure measurement is obtained. A processor of the device  100  may determine whether a relationship between a measurement (or measurements) of the air pressure and a measurement (or measurements) of the air flow matches an expected air pressure to air flow relationship. When the relationship between the measurement(s) of the air pressure and the measurement(s) of the air flow do not match the expected air pressure to air flow relationship (e.g., when there is an air flow but no air pressure), the processor may determine that the device  100  has a damaged seal (e.g., a damaged gasket  126  or cracked front cover  106 ) and perform one or more operations, such as transmitting a notification to a user of the device  100 . In some cases, the notification may include a warning that the interior volume  124  is no longer sealed. The warning may be viewable through the display surface. In some cases, the notification may include a sound, a voice alert, or a haptic output. 
     In the case of a severely damaged seal, the air pressure within the interior volume  124  may not change (or minimally change) in response to a force applied to the display surface. Similarly, the air flow sensor  130  may not register an air flow (or register a minimal air flow). Thus, in the case of a severely damaged seal, a measurement (or measurements) obtained from just the pressure sensor  128  or just the air flow sensor  130  when a user is determined to be touching the display surface (e.g., because of a touch indication provided by a touch sensor) may be sufficient for a processor to determine that the device  100  has a damaged seal. 
       FIG. 5  illustrates an example method  500  of determining an amount of force applied to a display surface of a mobile electronic device. The method  500  may be performed by, or using, any of the force sensors and/or processors described herein. The method  500  may also be performed by, or using, other force sensors or processors. 
     At block  502 , the method  500  may include measuring an air pressure within an interior volume of the mobile electronic device. The operation(s) at block  502  may be performed by one or more of the pressure sensors described herein. 
     At block  504 , the method  500  may optionally include measuring a temperature within the interior volume. The operation(s) at block  504  may be performed by one or more of the temperature sensors described herein. 
     At block  506 , the method  500  may include measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile electronic device. In some embodiments, measuring the air flow through the port may include integrating all air flow through the port over a period of time. The operation(s) at block  506  may be performed by one or more of the air flow sensors described herein. 
     At block  508 , the method  500  may include determining the amount of force applied to the display surface using the measurement of the air pressure and the measurement of the air flow, and optionally the measurement of the temperature. The operation(s) at block  508  may be performed by one or more of the processors described herein. 
     In some embodiments, the method  500  may include monitoring the display surface for touches (e.g., using a touch sensor of the mobile electronic device), and determining the amount of force applied to the display surface in response to detecting a touch on the display surface. In some embodiments, the operations at block  502 ,  504 , and/or  506  may also be performed in response to detecting the touch on the display surface. 
     In some embodiments, the method  500  may include calibrating an air flow sensor that is used to measure the air flow through the port. The calibration may be performed in response to detecting no touch on the display surface. 
       FIG. 6  illustrates an example method  600  of notifying a user of a mobile communication device that the mobile communication device has a damaged seal. The method  600  may be performed by, or using, any of the force sensors and/or processors described herein. The method  600  may also be performed by, or using, other force sensors or processors. 
     At block  602 , the method  600  may include measuring an air pressure within an interior volume of the mobile communication device. The operation(s) at block  602  may be performed by one or more of the pressure sensors described herein. 
     At block  604 , the method  600  may include measuring an air flow through a port connecting the interior volume to an environment exterior to the mobile communication device. In some embodiments, measuring the air flow through the port may include integrating all air flow through the port over a period of time. The operation(s) at block  604  may be performed by one or more of the air flow sensors described herein. 
     At block  606 , the method  600  may include determining whether a relationship between the measured air pressure and the measured air flow matches an expected air pressure to air flow relationship. The operation(s) at block  606  may be performed by one or more of the processors described herein. 
     At block  608 , the method  600  may include transmitting to the user, in response to determining the relationship between the measured air pressure and the measured air flow does not match the expected air pressure to air flow relationship, a notification indicating that the mobile communication device has the damaged seal. In some embodiments, the notification may include a visual notification displayed on a display of the mobile communication device. In some cases, the notification may include a sound, a voice alert, or a haptic output. The operation(s) at block  608  may be performed by one or more of the processors described herein. 
     In some embodiments, the method  600  may include detecting a touch on a display surface of the mobile communication device (e.g., using a touch sensor of the mobile electronic device), and determining whether the relationship between the measured air pressure and the measured air flow matches the expected air pressure to air flow relationship in response to detecting the touch on the display surface. In some embodiments, the operations at block  602  and/or  604  may also be performed in response to detecting the touch on the display surface. 
       FIG. 7  shows a sample electrical block diagram of an electronic device  700 , which may be the electronic device described with reference to  FIGS. 1A-1C . The electronic device  700  may include a display  702  (e.g., a light-emitting display), a processor  704 , a power source  706 , a memory  708  or storage device, a sensor system  710 , and an input/output (I/O) mechanism  712  (e.g., an input/output device and/or input/output port). The processor  704  may control some or all of the operations of the electronic device  700 . The processor  704  may communicate, either directly or indirectly, with substantially all of the components of the electronic device  700 . For example, a system bus or other communication mechanism  714  may provide communication between the processor  704 , the power source  706 , the memory  708 , the sensor system  710 , and/or the input/output mechanism  712 . 
     The processor  704  may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor  704  may be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. In some embodiments, the processor  704  may include or be an example of the processor described with reference to  FIG. 1C . 
     In some embodiments, the components of the electronic device  700  may be controlled by multiple processors. For example, select components of the electronic device  700  may be controlled by a first processor and other components of the electronic device  700  may be controlled by a second processor, where the first and second processors may or may not be in communication with each other. 
     The power source  706  may be implemented with any device capable of providing energy to the electronic device  700 . For example, the power source  706  may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power source  706  may be a power connector or power cord that connects the electronic device  700  to another power source, such as a wall outlet. 
     The memory  708  may store electronic data that may be used by the electronic device  700 . For example, the memory  708  may store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, or focus settings. The memory  708  may be configured as any type of memory. By way of example only, the memory  708  may be implemented as random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such devices. 
     The electronic device  700  may also include one or more sensors defining the sensor system  710 . The sensors may be positioned substantially anywhere on the electronic device  700 . The sensor(s) may be configured to sense substantially any type of characteristic, such as but not limited to, touch, force, pressure, air flow, temperature, light, heat, movement, relative motion, biometric data, and so on. For example, the sensor system  710  may include a touch sensor, a force sensor, a temperature sensor, a position sensor, a light or optical sensor, an accelerometer, a pressure sensor (e.g., a pressure transducer), an air flow sensor, a gyroscope, a magnetometer, a health monitoring sensor, and so on. Additionally, the one or more sensors may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasound, piezoelectric, and thermal sensing technology. In some embodiments, the sensor(s) may include the touch sensors, pressure sensors, air flow sensors, temperature sensors, and other sensors described herein. 
     The I/O mechanism  712  may transmit and/or receive data from a user or another electronic device. An I/O device may include a display, a touch sensing input surface such as a track pad, one or more buttons (e.g., a graphical user interface “home” button, or one of the buttons described herein), one or more cameras, one or more microphones or speakers, one or more ports such as a microphone port, and/or a keyboard. Additionally or alternatively, an I/O device or port may transmit electronic signals via a communications network, such as a wireless and/or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet connections. The I/O mechanism  712  may also provide feedback (e.g., a haptic output) to a user, and may include the haptic engine of any of the modules or button assemblies described herein. 
     The foregoing description, for purposes of explanation, uses specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art, after reading this description, that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art, after reading this description, that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20180927
Publication Date: 20191203
Grant Date: 20191203
Priority Date: 20180927
Inventors: SMITH, JOHN STEPHEN
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1643", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01L1/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01L1/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01L1/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01L1/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04105", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01M3/3272", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01M3/3254", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01L1/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01L1/142", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01L1/005", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 68695974