Abstract:
Ultrasound is used to detect the proximity of an object and whether the object touches a body of an electronic device. A transducer may produce ultrasonic waves to air and to the device body simultaneously. The transducer is connected to the body, allowing a vibration of the ultrasonic waves to travel in the body. The vibration characteristics, for example the decay, change in the body when the body is touched. The decay may be analyzed to detect the touch. The transducer produces the ultrasonic waves to the airspace in proximity to the electronic device. Waves returning from the airspace, for example, after reflecting back from a proximate object, are analyzed and proximity or a gesture of the object may be detected.

Description:
BACKGROUND 
       [0001]    Hand-held devices, such as mobile phones, use capacitive sensors to detect physical phenomena such as the proximity, touch or touch gesture of the user, where the sensors can detect when the user is either holding or close to the device. Capacitive sensors are effective with insulant device body or device housing materials such as plastic. However, many hand-held devices use conductive material such as metals for the body or housing material, which can block the capacitance and specific arrangements that may be needed to enable the use of capacitive sensors. 
       SUMMARY 
       [0002]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
         [0003]    Ultrasound is used to detect the proximity of an object and whether the object touches a body of an electronic device. A transducer may produce ultrasonic waves to air and to the device body simultaneously. The transducer is connected to the body, allowing the ultrasonic waves to produce a vibration in the body. The vibration characteristics, for example the decay, change when the body is touched. The decay may be analyzed to detect the touch. The transducer produces ultrasonic waves to the airspace in proximity to the electronic device. The ultrasonic waves returning from the airspace, for example, after reflecting back from a proximate object, are analyzed and the proximity or a gesture of the object may be detected. 
         [0004]    Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings. The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known hand-held devices. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0005]    The present description will be better understood from the following detailed description read in light of the accompanying drawings, wherein: 
           [0006]      FIG. 1  is a schematic diagram of one example of an electronic device with touch and proximity sensing elements; 
           [0007]      FIG. 2  is a schematic cross-section of one example of an electronic device with an ultrasonic transducer, wherein a transducer is positioned inside a housing or body; 
           [0008]      FIG. 3  is a schematic cross-section of one example of an electronic device with an ultrasonic transducer, wherein a transducer is positioned outside a housing or body; 
           [0009]      FIG. 4  is an example of the electronic device, wherein the electronic device comprises multiple touch sensitive areas; 
           [0010]      FIG. 5  is an example of a graph illustrating the sound wave energy from a receiving transducer as a function of time; 
           [0011]      FIG. 6  is an example of the electronic device comprising multiple receiving transducers; and 
           [0012]      FIG. 7  is an example of a graph illustrating the received signal amplitude from a receiving transducer as a function of time. 
       
    
    
       [0013]    Like reference numerals are used to designate like parts in the accompanying drawings. 
       DETAILED DESCRIPTION 
       [0014]    The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. However, the same or equivalent functions and sequences may be accomplished by different examples. 
         [0015]    Although the present examples are described and illustrated herein as being implemented in a mobile phone, the device described is provided as an example and not a limitation. As those skilled in the art will appreciate, the present examples are suitable for application in a variety of different types of mobile and/or hand-held apparatuses, e.g. in tablets, laptops or gaming consoles. 
         [0016]      FIG. 1  shows one example of an electronic device with touch and proximity sensing elements, wherein one embodiment of the electronic device is a mobile phone. The electronic device comprises a body  100 , wherein a portion of the body is covered with a housing. The electronic device also comprises a display  110 , a speaker  121 , a microphone  130  and keys  140 . The speaker  121  is inside the electronic device and the housing comprises an opening  120 , wherein the speaker sound exits the electronic device. An ultrasound wave may also exit from the same opening  120  as the speaker sound. The electronic device may also comprise other features such as a camera  150 . The electronic device may comprise a second set of keys  161 ,  162 ,  163 ,  164 ,  165  configured around the body  100 , wherein the keys  140  comprise push buttons and the second set of keys  161 ,  162 ,  163 ,  164 ,  165  comprise a touch sensing function. The electronic device may comprise other key and/or button configurations with different functions for detecting touching or pushing. The placement of key and button configuration is presented as an example, wherein the number of buttons and keys may vary. Key and/or button configuration may comprise mechanical buttons, buttons with capacitive sensing or buttons configured to the display with sensing function. 
         [0017]      FIG. 2  shows a cross-section of one example of an electronic device with an ultrasonic transducer. The illustration is only exemplary, wherein the proportions of the drawing are not essential for fully executing the functionality of the device. A body  200  is made of a material that allows ultrasonic waves and other sound waves to travel through the body  200 . The material may be for example glass, plastic or metal, such as stainless steel or aluminum. The body may be partially covered with a housing  201 , for example the middle of the electronic device comprises the body  200  that has a housing  201  surrounding the edges and backside of the electronic device. The housing  201  may be integrated into the body  200  and it may be made of the same material as the body  200 . 
         [0018]    A first transducer  210  is connected to the body  200 , in this example inside the housing  201 . The first transducer  210  is configured to produce a first ultrasonic wave  220  into a volume of airspace in proximity to the electronic device. The first transducer  210  is for example a piezoelectric transducer. A transducer is a device that converts a signal in one form of energy to another form of energy or, as in this example, the first transducer  210  converts an electric signal into vibrations. The housing  201  comprises a first opening  202  to allow the first wave  220  to travel out from the housing and into the airspace. The body  200  and the housing  201  form a space  203  around the first transducer  210  that improves the production of the first wave, wherein the space  203  forms a resonant cavity for the acoustic wave. In an embodiment, the electronic device comprises a housing  201  forming a cavity  203  over the body  201 , wherein the first transducer  210  is positioned inside the cavity  203 , and the housing  201  comprises a first opening  202  configured to deliver the first wave  220  from the cavity  203  into a volume of airspace in proximity to the electronic device. 
         [0019]    In an embodiment, the electronic device comprises a speaker  204 , wherein the first opening  202  is configured to deliver sound waves from the speaker  204  into a volume of airspace in proximity to the electronic device. The opening  202  may be used for the speaker sound as well as the ultrasonic waves. The speaker  204  and the first transducer  210  may send sound waves at the same time or the speaker  204  may be silenced in order to send the ultrasonic waves from the first transducer  210 . In an embodiment, the speaker  204  is used to produce the first wave  220 . The first wave  220  diffracts from the opening  202  according to the Huygens-Fresnel principle, wherein the opening  202  may be used as a starting point of the first wave  220  in the volume of airspace in proximity to the electronic device. 
         [0020]    In an embodiment, the first wave  220  is an ultrasonic wave. The first wave  220  is transmitted as an oscillating sound pressure wave, wherein the frequency is over the audible range of the human ear, for example more than 20 kHz. The first wave may be transmitted as a burst, wherein the first wave  220  is followed by a pause. One burst may comprise a single sound wave. The first wave  200  exits from the opening  202  radially to the surrounding airspace. In this example, the first wave  220  hits an object  221  in proximity to the electronic device and reflects back to a first receiving transducer  222 . The object  221  may be a finger or hand of the user. The first receiving transducer  222  is configured to receive the first wave; the receiving transducer may be a microphone suitable for receiving ultrasonic waves, or a piezoelectric microphone. The first receiving transducer may receive the first wave from two sources: directly from the opening  202  and as a reflection from the object  221 . 
         [0021]    A proximity sensing element  230  is configured to detect proximity of an object from an echoed or reflected first wave  220 . The information of the first ultrasonic wave  220  travelled directly from the opening  202  may be used to analyze the proximity of the object  221  together with the echoed or reflected first wave  220 . The object proximity may be calculated in relation to the opening  202  and the reflected first wave  220  received by the first receiving transducer  222 . The electronic device may comprise multiple first receiving transducers; for example in  FIG. 2  another first receiving transducer  223  is illustrated. The difference between the reflected ultrasonic waves received by multiple first receiving transducers  222 ,  223  may be used to detect movement of the object  221 , direction of the movement or shape of the object  221 . The proximity sensing element  230  is electrically connected to the first transducer  210  and at least to the first receiving transducer  222 . The proximity sensing element  230  comprises a processor and a memory storing instructions that, when executed, control the operation of the proximity sensing element  230 . The proximity sensing element  230  may be a discrete element in the electronic device, or the functionalities may be integrated to other processor elements of the electronic device. 
         [0022]    The first transducer  210  is configured to produce a second ultrasonic wave  240  to the body  200 . A connection between the first transducer  210  and the body  200  is configured to deliver the second wave  240  to the body  200 . The connection may be a direct mounting to the body  200 ; the transducer  210  may be glued or screwed to the body  200 . As illustrated in  FIG. 3 , the first transducer  210  may be configured to a portion of the housing  201 , wherein the connection  241  between the housing  201  and the body is configured to pass the second wave  240  to the body  200 . The first transducer  210  may be positioned inside the body  200 , inside the housing  201  or on top of the housing  201  or body  200 . 
         [0023]    Referring to  FIG. 2 , a second receiving transducer  241  is configured to receive the second wave  240  from the body  200 . In an embodiment, the first transducer  210  is configured to produce the first wave  220  and the second wave  240  simultaneously. The vibration produced by the first transducer  210  travels in bursts through the body  200  and the airspace simultaneously. A touch sensing element  250  is configured to detect a touch by analyzing the second wave  240  received by the second receiving transducer  241 . The touch sensing element  250  is electrically connected to the first transducer  210  and at least to the second receiving transducer  241 . The touch sensing element  250  comprises a processor and a memory storing instructions that, when executed, control the operation of the touch sensing element  250 . The touch sensing element  250  may be a discrete element in the electronic device, integrated to the proximity sensing element  230 , or the functionalities may be integrated to other processor elements of the electronic device. 
         [0024]      FIG. 4  shows an embodiment, wherein the electronic device comprises multiple touch sensitive areas  401 ,  402 ,  403  that are connected to at least one second receiving transducer, such as the second receiving transducer  241  of  FIG. 2 . The electronic device may comprise more touch sensitive areas or second receiving transducers on other sides of the electronic device. The second receiving transducers are connected to the body  200 , for example to a portion of the body  200 , wherein the shape of the body  200  is at least partially isolated from other second receiving transducers. The isolation may be for example a protrusion formed to the body  200  that protrudes through the housing  201 , allowing the user to touch it. In this example the protrusion formed to the body  200  is illustrated as touch sensitive areas  401 ,  402 ,  403 . The shape may be a groove around the second receiving transducer that isolates the ultrasonic characteristics to be mixed when touching other portions of the body  200 . The shape may be configured inside the housing, wherein it is not visible to the user. The second receiving transducer  241  and the touch sensing element  250  are configured to sense the touch by analyzing the decay or the change in the vibration characteristics of the second wave  240  received from the body  240 . 
         [0025]      FIG. 5  shows an example of a graph illustrating the ultrasonic wave energy from the second receiving transducer as a function of time. When the user touches the body of the electronic device, the decay of the ultrasonic wave changes. As in a musical instrument, for example in a guitar string, the string vibrates freely unless the player dampens the string. When the user touches the body in an area near the second receiving transducer, the vibration dampens faster. Graph  501  illustrates the decay of the second wave when the user is not touching the body and graph  502  illustrates the decay of the second wave when the user touches the body. The difference  510  highlights the change in the decay, allowing the touch sensing element to detect that a portion of the body is touched. 
         [0026]    The vibration characteristics may also change as a response to touch. For example the characteristic frequency of the vibration relating at least to a portion of the body  200  may change, resembling the effect of a musical instrument. The body  200  may be shaped to comprise different portions that have different resonant frequencies, thereby allowing the separation of the touch for different portions of the body. This enables multiple touch sensitive areas that may be assigned to different functions as illustrated in  FIG. 4 . The first transducer  210  may transmit different frequencies to enable the detection of touch from second receiving transducers for different portions of the body  200 . 
         [0027]      FIG. 7  shows an example of the received signal amplitude from the receiving transducer as a function of time. Graph  702  illustrates the amplitude when the touch sensitive area of the electronic device is not touched. Graph  701  illustrates the amplitude response of the electronic device when a first touch sensitive area of the body is touched. The amplitude curve remains at a higher level for a longer period, but soon drops below the compared graph  702 . Graph  703  illustrates the amplitude response of the electronic device, when a second touch sensitive area of the body is touched. The amplitude initially dampens faster, but remains at a higher level for a longer period than graph  701  or graph  702 . Different protrusions or shapes at the body may result in different amplitude responses. 
         [0028]      FIG. 6  shows an embodiment of the electronic device comprising multiple first receiving transducers  621 ,  622 ,  623 ,  624 ,  625 . The first transducer  610  is in this example positioned on top of the body and housing  600 . The first receiving transducers  621 ,  622 ,  623 ,  624 ,  625  may be positioned over or inside the housing  600 , wherein the ultrasonic waves travel to the receiving transducers through an opening. Multiple first receiving transducers  621 ,  622 ,  623 ,  624 ,  625  configured on different sides of the housing  600  allow more accurate positioning of the object in the airspace around the electronic device. The increasing number of first receiving transducers  621 ,  622 ,  623 ,  624 ,  625  may allow detecting different reflections of the ultrasonic wave, thereby increasing the resolution of detecting the object, the gesture of the object or the shape of the object. Multiple first receiving transducers  621 ,  622 ,  623 ,  624 ,  625  allow receiving the reflections from different sides of the electronic device. 
         [0029]    An embodiment discloses an electronic device, comprising: a body; a first transducer connected to the body and configured to produce a first wave into a volume of airspace in proximity to the electronic device; a first receiving transducer configured to receive the first wave; a proximity sensing element configured to detect proximity of an object from an echoed first wave; the first transducer configured to produce a second wave, wherein a connection between the first transducer and the body is configured to deliver the second wave to the body; a second receiving transducer configured to receive the second wave from the body; and a touch sensing element configured to detect a touch by analyzing the second wave received by the second receiving transducer. In an embodiment of the electronic device, the first transducer is configured to produce the first wave and the second wave simultaneously. An embodiment discloses an electronic device, comprising: a body; a first transducer connected to the body and configured to produce a first wave into a volume of airspace in proximity to the electronic device; means for receiving the first wave; means for detecting proximity of an object from an echoed first wave; the first transducer configured to produce a second wave, wherein a connection between the first transducer and the body is configured to deliver the second wave to the body; means for receiving the second wave from the body; and means for detecting a touch by analyzing the second wave received by the second receiving transducer. In an embodiment of the electronic device, the first transducer is configured to produce the first wave and the second wave simultaneously. In an embodiment of the electronic device, the first transducer is a piezoelectric transducer. In an embodiment of the electronic device, the first wave is an ultrasonic wave. In an embodiment, the electronic device comprises at least two second receiving transducers configured to receive the second wave from the body. In an embodiment of the electronic device, the touch sensing element is configured to sense the touch by analyzing the decay of the second wave received from the body. In an embodiment, the electronic device comprises a housing forming a cavity over the body, wherein the first transducer is positioned inside the cavity, and the housing comprises a first opening configured to deliver the first wave from the cavity into the volume of airspace in proximity to the electronic device. In an embodiment, the electronic device comprises a speaker, wherein the first opening is configured to deliver sound waves from the speaker into the volume of airspace in proximity to the electronic device. 
         [0030]    An embodiment discloses a system, comprising: a body; a first transducer connected to the body and configured to produce a first wave into a volume of airspace in proximity to the body; a first receiving transducer configured to receive the first wave; a proximity sensing element configured to detect proximity of an object from an echoed first wave; the first transducer configured to produce a second wave, wherein a connection between the first transducer and the body is configured to deliver the second wave to the body; a second receiving transducer configured to receive the second wave from the body; and a touch sensing element configured to detect a touch by analyzing the second wave received by the second receiving transducer. An embodiment discloses a system, comprising: a body; a first transducer connected to the body and configured to produce a first wave into a volume of airspace in proximity to the electronic device; means for receiving the first wave; means for detecting proximity of an object from an echoed first wave; the first transducer configured to produce a second wave, wherein a connection between the first transducer and the body is configured to deliver the second wave to the body; means for receiving the second wave from the body; and means for detecting a touch by analyzing the second wave received by the second receiving transducer. In an embodiment of the system, the first transducer is configured to produce the first wave and the second wave simultaneously. In an embodiment of the system, the first transducer is a piezoelectric transducer. In an embodiment of the system, the first wave is an ultrasonic wave. In an embodiment, the system comprises at least two second receiving transducers configured to receive the second wave from the body. In an embodiment of the system, the touch sensing element is configured to sense the touch by analyzing the decay of the second wave received from the body. In an embodiment, the system comprises a housing forming a cavity over the body, wherein the first transducer is positioned inside the cavity, and the housing comprises a first opening configured to deliver the first wave from the cavity into the volume of airspace in proximity to the body. In an embodiment, the system comprises a speaker, wherein the first opening is configured to deliver sound waves from the speaker into the volume of airspace in proximity to the electronic device. 
         [0031]    An embodiment discloses a method of providing user inputs to an electronic device, the method comprising: producing a first wave into a volume of airspace in proximity to the electronic device by a first transducer connected to a body of the electronic device; receiving the first wave by a first receiving transducer; detecting proximity of an object from an echoed first wave by a proximity sensing element; producing a second wave by the first transducer and delivering the second wave to the body through a connection between the first transducer and the body; receiving the second wave from the body by a second receiving transducer configured for: detecting a touch by analyzing the second wave received by the second receiving transducer on a touch sensing element. An embodiment discloses a method of providing user inputs to an electronic device, the method comprising: producing a first wave into a volume of airspace in proximity to the electronic device by a first transducer connected to a body of the electronic device; receiving the first wave by a first receiving means; detecting proximity of an object from an echoed first wave; producing a second wave by the first transducer and delivering the second wave to the body through a connection between the first transducer and the body; and receiving the second wave from the body by a second receiving means. In an embodiment, the method comprises producing the first wave and the second wave simultaneously. In an embodiment, the method comprises analyzing the decay of the second wave received from the body to detect the touch. In an embodiment, the first wave is an ultrasonic wave. 
         [0032]    An embodiment discloses an electronic device, comprising a body; a first transducer connected to the body and configured to produce a wave into a volume of airspace in proximity to the electronic device and into the body; a first receiving transducer configured to receive an echoed wave based on the wave into the volume of airspace; a proximity sensing element configured to detect proximity of an object by analyzing the echoed wave received by the first receiving transducer; a second receiving transducer configured to receive the wave into the body; and a touch sensing element configured to detect a touch by analyzing the wave received by the second receiving transducer. 
         [0033]    The first transducer may be used to transmit ultrasonic waves to air and to the body, thereby reducing the number of components to transmit the waves. As the components are shared, a more cost efficient implementation is achieved. Proximity sensors may be used with the ultrasonic proximity sensors and capacitive touch sensing technologies may be used with the ultrasonic touch sensing as the ultrasound may not limit the use of other sensing functions. Gestures may be used to control functions of the electronic device. When the electronic device detects that the user is touching the device, the proximity detection or proximity detection may be turned off to save power. 
         [0034]    Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware components or hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program-specific Integrated Circuits (ASICs), Program-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs). For example, some or all of the touch sensing element functionality or proximity sensing element functionality may be performed by one or more hardware logic components. 
         [0035]    An example of the apparatus or a system described hereinbefore is a computing-based device comprising one or more processors which may be microprocessors, controllers or any other suitable type of processors for processing computer executable instructions to control the operation of the device in order to control one or more sensors, receive sensor data and use the sensor data. Platform software comprising an operating system or any other suitable platform software may be provided at the computing-based device to enable application software to be executed on the device. 
         [0036]    The computer executable instructions may be provided using any computer-readable media that is accessible by computing based device. Computer-readable media may include, for example, computer storage media such as memory and communications media. Computer storage media, such as memory, includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device. In contrast, communication media may embody computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanism. As defined herein, computer storage media does not include communication media. Therefore, a computer storage medium should not be interpreted to be a propagating signal per se. Propagated signals may be present in a computer storage media, but propagated signals per se are not examples of computer storage media. Although the computer storage media is shown within the computing-based device, it will be appreciated that the storage may be distributed or located remotely and accessed via a network or other communication link, for example by using a communication interface. 
         [0037]    The computing-based device may comprise an input/output controller arranged to output display information to a display device which may be separate from or integral to the computing-based device. The display information may provide a graphical user interface, for example, to display hand gestures tracked by the device using the sensor input or for other display purposes. The input/output controller is also arranged to receive and process input from one or more devices, such as a user input device (e.g. a mouse, keyboard, camera, microphone or other sensor). In some examples the user input device may detect voice input, user gestures or other user actions and may provide a natural user interface (NUI). This user input may be used to configure the device for a particular user such as by receiving information about bone lengths of the user. In an embodiment, the display device may also act as the user input device if it is a touch sensitive display device. The input/output controller may also output data to devices other than the display device, e.g. a locally connected printing device. 
         [0038]    The term “computer” or “computing-based device” is used herein to refer to any device with such processing capability that it can execute instructions. Those skilled in the art will realize that such processing capabilities are incorporated into many different devices and therefore the terms “computer” and “computing-based device” each include PCs, servers, mobile telephones (including smart phones), tablet computers, set-top boxes, media players, games consoles, personal digital assistants and many other devices. 
         [0039]    The methods described herein may be performed by software in machine readable form on a tangible storage medium, e.g. in the form of a computer program comprising computer program code means adapted to perform all the steps of any of the methods described herein when the program is run on a computer and where the computer program may be embodied on a computer readable medium. Examples of tangible storage media include computer storage devices comprising computer-readable media such as disks, thumb drives, memory etc. and do not only include propagated signals. Propagated signals may be present in a tangible storage media, but propagated signals per se are not examples of tangible storage media. The software can be suitable for execution on a parallel processor or a serial processor such that the method steps may be carried out in any suitable order, or simultaneously. 
         [0040]    This acknowledges that software can be a valuable, separately tradable commodity. It is intended to encompass software, which runs on or controls “dumb” or standard hardware, to carry out the desired functions. It is also intended to encompass software which “describes” or defines the configuration of hardware, such as HDL (hardware description language) software, as is used for designing silicon chips, or for configuring universal programmable chips, to carry out desired functions. 
         [0041]    Those skilled in the art will realize that storage devices utilized to store program instructions can be distributed across a network. For example, a remote computer may store an example of the process described as software. A local or terminal computer may access the remote computer and download a part or all of the software to run the program. Alternatively, the local computer may download pieces of the software as needed, or execute some software instructions at the local terminal and some at the remote computer (or computer network). Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc. 
         [0042]    Any range or device value given herein may be extended or altered without losing the effect sought. 
         [0043]    Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims. 
         [0044]    It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to “an” item refers to one or more of those items. 
         [0045]    The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought. 
         [0046]    The term “comprising” is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements. 
         [0047]    It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this specification.