Patent Publication Number: US-8120625-B2

Title: Method and apparatus using multiple sensors in a device with a display

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a Continuation-In-Part application of U.S. patent application Ser. No. 09/875,477, filed Jun. 6, 2001 now U.S. Pat. No. 7,289,102, which claims priority from a U.S. Provisional application having Ser. No. 60/218,748, filed on Jul. 17, 2000 and entitled “METHOD AND APPARATUS USING MULTIPLE SENSORS IN A MOBILE DEVICE” and is a Continuation-In-Part of U.S. patent application Ser. No. 10/162,487, filed Jun. 3, 2002 now U.S. Pat. No. 7,302,280, which was a Continuation-In-Part of U.S. patent application Ser. No. 09/875,477 filed Jun. 6, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to devices with displays. In particular, the present invention relates to computing and mobile devices. 
     Mobile devices, such as personal information managers (PIMs), tablet PCs, cellular telephones, pagers, watches, and wearable computers typically include one or more buttons or touch screens through which the mobile device receives explicit instructions from the user. For example, the user can press buttons to explicitly instruct the device to enter a full-power mode, activate an application, or change the orientation of a display. 
     Although the devices are responsive to information provided through such explicit instructions, they are generally not responsive to information that is present in the manner in which the device is being handled by the user. For example, the devices do not automatically enter a full-power mode, even when the user is holding the device in a manner that is consistent with wanting to use the device. 
     Because prior art devices are generally not responsive to the manner in which the user is holding the devices, the user is forced to enter explicit instructions into the device to achieve various functions. In light of this, mobile devices are needed that can sense how they are being handled in order to perform certain background functions that expand the functionality of the mobile device without requiring the user to perform any additional actions. 
     SUMMARY OF THE INVENTION 
     In a device having a display, a change in focus for an application is used with a requested usage of a context attribute to change the amount of information regarding the context attribute that is sent to another application. A method of changing the orientation of images on a device&#39;s display detects movement followed by an end of movement of the device. The orientation of the device is then determined and is used to set the orientation of images on the display. A method of setting the orientation of a display also includes storing information regarding an item displayed in a first orientation before changing the orientation. When the orientation is returned to the first orientation, the stored information is retrieved and is used to display the item in the first orientation. The stored information can include whether the item is to appear in the particular orientation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of the components of a mobile device under one embodiment of the present invention. 
         FIG. 2  is a bottom view of a mobile device of one embodiment of the present invention. 
         FIG. 3  is a front view of the mobile device of  FIG. 2 . 
         FIG. 4  is a back view of the mobile device of  FIG. 2 . 
         FIG. 5  is a left side view of the mobile device of  FIG. 2 . 
         FIG. 6  is a right side view of the mobile device of  FIG. 2 . 
         FIG. 7  is a front view of a second embodiment of a mobile device. 
         FIG. 8  is a back view of the mobile device of  FIG. 7 . 
         FIG. 9  is a graph of distance between a user and a mobile device as a function of proximity sensor levels. 
         FIG. 10  is a block diagram of components used to practice several embodiments of the present invention. 
         FIG. 11  is a front view of a mobile device in a portrait orientation. 
         FIG. 12  is a front view of a mobile device in a landscape orientation. 
         FIG. 13  is a chart showing the display orientations for various combinations of forward/back tilt and left/right tilt. 
         FIGS. 14 and 15  show a mobile device in two different orientations. 
         FIG. 16  shows a front view of a mobile device with an orientation feedback icon displayed. 
         FIG. 17  shows a mobile device in a landscape orientation with a word-processing application. 
         FIG. 18  shows a mobile device in a portrait orientation with an e-mail application. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a block diagram of a mobile device  200 , which is an exemplary environment for embodiments of the present invention. Mobile device  200  includes a microprocessor  202 , memory  204 , input/output (I/O) components  206 , and a communication interface  208  for communicating with remote computers or other mobile devices. In one embodiment, the afore-mentioned components are coupled for communication with one another over a suitable bus  210 . 
     Memory  204  is a computer readable media, which can be any available media that can be accessed by processor  202  and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and nonremovable 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, TOM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by processor  202 . Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above should also be included within the scope of computer readable media. 
     The particular computer readable medium used in a mobile device is a function of the size of the device and the power capacity of the device. For example, a tablet PC will typically include one or more disk drives where as a PIM will typically only include a random access memory (RAM) with a battery back-up module (not shown) such that information stored in memory  204  is not lost when the general power to mobile device  200  is shut down. 
     A portion of memory  204  is preferably allocated as addressable memory for program execution, while another portion of memory  204  is preferably used for storage. 
     Memory  204  includes an operating system  212 , application programs  214 , and an object store  216 . During operation, operating system  212  is preferably executed by processor  202  from memory  204 . Operating system  212 , in one preferred embodiment, is a WINDOWS® CE brand operating system commercially available from Microsoft Corporation. In Tablet PC embodiments, Windows® XP brand operating system available from Microsoft Corporation is utilized. Operating system  212  is preferably designed for mobile devices, and implements database features that can be utilized by applications  214  through a set of exposed application programming interfaces and methods. The objects in object store  216  are maintained by applications  214  and operating system  212  at least partially in response to calls to the exposed application programming interfaces and methods. 
     Communication interface  208  represents numerous devices and technologies that allow mobile device  200  to send and receive information. The devices include wired and wireless modems, satellite receivers and broadcast tuners to name a few. Mobile device  200  can also be directly connected to a computer to exchange data therewith. In such cases, communication interface  208  can be an infrared transceiver or a serial, parallel, USB, or Firewire communication connection, all of which are capable of transmitting streaming information. 
     Input/output components  206  include a variety of input devices that have previously been found on mobile devices such as a touch-sensitive screen or transparent tablet overlay sensitive to properties of a special stylus including position, proximity to the screen, pressure, azimuth, elevation, which end of the stylus is being used (e.g. writing tip on one end, eraser on the other end) and possibly a unique ID encoded in the stylus, buttons, rollers, and a microphone as well as a variety of output devices including an audio generator, a vibrating device, and a display. The devices listed above are by way of example and need not all be present on mobile device  200 . 
     Mobile device  200  also includes additional input devices under the present invention. Under one embodiment, these input devices are connected to the mobile device through a separate serial port  250  and a peripheral interface controller (PIC) microprocessor  252 . In other embodiments, these additional devices are connected to processor  202  through communication interface  208  and PIC microprocessor  252  or through PIC microprocessor  252  directly. Under one embodiment, a microchip 16C73A peripheral interface controller is used as the PIC microprocessor. In still further embodiments, PIC microprocessor  252  is not present and the input devices are connected to processor  202  through various ports such as serial port  250  or through communication interface  208 , or through memory-mapped I/O or direct connection to the system processor(s). 
     Under the embodiment of  FIG. 1 , The additional input devices include a set of touch sensors such as touch sensors  254  and  256 . Touch sensors  254  and  256  are provided to a separate peripheral interface controller microprocessor  276  which converts the touch signals into digital values and provides the digital values to PIC microprocessor  252 . In other embodiments, touch sensors  254  and  256  are connected directly to analog or digital inputs in PIC microprocessor  252  instead of being connected to PIC  276  or are connected to processor  202 . 
     The input devices also include a dual axis linear accelerometer tilt sensor  258  capable of detecting forward/back tilt, left/right tilt, and linear accelerations such as those resulting from vibrations or movement. 
     The input devices also include a light sensor  260 , a proximity sensor  262  consisting of an infrared transmitter  264  and an infrared receiver  266 , a digital compass (e.g. a single or multiple axis magnetometer)  284 , and a gravity switch  282 . The sensing signals from the infrared receiver  266 , linear accelerator  258 , light sensor  260 , digital compass  284 , and gravity switch  282  may be provided through respective amplifiers  270 ,  272 ,  274 ,  285  and  287  to analog inputs of PIC microprocessor  252 . These analog inputs are connected to analog-to-digital converters within PIC microprocessor  252 . In other embodiments, the sensors provide a digital output and thus are connected to digital inputs on the microprocessor. In further embodiments, the input devices also include a temperature sensor. 
     PIC microprocessor  252  also includes a connection to the power bus of mobile device  200 , which is shown as connection  278  in  FIG. 1 . PIC microprocessor  252  also includes a connection to a power switch  280 , which enables PIC microprocessor  252  to turn mobile device  200  on and off. Note that PIC microprocessor  252  always receives power and, under one embodiment, is able to control which of the sensors receives power at any one time. This allows PIC microprocessor  252  to manage power consumption by only sending power to those sensors that it anticipates will need to be active. 
     Under one embodiment, PIC microprocessor  252  continuously samples the sensors and transmits packets representing the state of these sensors at a rate of approximately 400 samples per second through serial port  250 . In some embodiments, samples are reported at lower speeds to conserve power and processing resources. Some sensors may be reported at different sampling rates than others (e.g. tilt may be updated more frequently than touch). 
     Under one embodiment, the touch sensors are capacitive touch sensors that are divided into two regions. In other embodiments, these sensors are implemented as a single detector pad. Under one embodiment, the touch sensors are spread across the back and sides of mobile device  200 . This is shown in more detail in  FIGS. 4-6  which show a back, left side view and right side view of the outside of mobile device  200 . In  FIGS. 4 ,  5 , and  6 , touch sensor  254  is shown as two regions  300  and  302 . Region  300  extends from the left side to the back of mobile device  200  and region  302  extends from the right side to the back of mobile device  200 . When a user touches either section  300  or  302 , the capacitance associated with the touched section changes indicating that the user has touched the device. Note that although the touch sensors are shown on the exterior of the device in the embodiment of  FIGS. 4-6 , in other embodiments, the touch sensor is located beneath an outer covering of the device. 
     Touch sensor  256  is shown in  FIG. 3 , which is a front view of mobile device  200 . In the embodiment of  FIG. 3 , touch sensor  256  is located on the left bezel of display screen  304 . In other embodiments, touch sensor  256  is located on the outer casing on the front portion of mobile device  200 , but not necessarily on bezel  306  of mobile device  200 . 
     In some embodiments, the touch sensors described above are realized using a plurality of independent touch sensors that each provides a separate touch signal. In other embodiments, the touch sensors are replaced with position sensors that indicate the location where the user is touching the device. Those skilled in the art will recognize that additional touch sensors may be added to the mobile device within the scope of the present invention. 
       FIGS. 7 and 8  indicate locations for touch sensors under one embodiment of a tablet PC. In  FIG. 7 , touch sensors  700 ,  702 ,  704 , and  706  are located at various locations around the perimeter of a display  708  on the front of tablet PC  701 . Sensors associated with display  708  are able to detect the location of a stylus  710  when it is near display  708  using inductive coupling between display  708  and conductors in stylus  710 . Under some embodiments, the sensors associated with display  708  are able to detect the proximity of stylus  710  as well as the azimuth of the stylus. 
       FIG. 8  provides a back view of tablet PC  701  and shows a touch sensor  712  located on the back surface of the tablet PC. 
     Tablet PC  701  can be of a slate form, in which the tablet PC only includes the display for input and does not include a keyboard. The slate forms of the tablet PC can be used with a docking station to provide a connection to other input devices and memory devices. 
     In other embodiments, the tablet PC is a convertible device with a keyboard. Under one convertible embodiment, the keyboard is attached to the display through a pivoting connection that allows the tablet PC to be in either a closed state or an open state. In such embodiments, the display is embedded in a top portion of the tablet PC and the keyboard is embedded in a bottom portion of the tablet PC. In the closed state, the top and bottom portions of the tablet PC are brought together so that the keyboard is hidden between the top and bottom portions while the display is visible on the exterior of the top portion. In the open state, the display pivots so that it faces the keyboard. 
     In another convertible embodiment, the display portion of the tablet PC is detachable from a keyboard and extended device portion, which can contain various disk drives and additional memory. In such embodiments, the back touch sensor  712  can be located on the back of the display portion or on the back of the keyboard portion. 
     Tilt sensor  258  is shown as a single dotted element  308  in  FIG. 3  and element  714  in  FIG. 7 . The tilt sensor is embedded within the casing of mobile device  200  and  701  and in one embodiment is located at a point about which users typically pivot mobile device  200  and  701  when tilting the device. Note that the tilt sensor&#39;s position within the mobile device is unimportant as it senses only the angle of its physical attitude with respect to gravity. The sensor&#39;s angular position within the device is important. 
     Under one embodiment, an Analog Devices ADXL202 two-axis linear accelerometer is used for tilt sensor  258 . Such a sensor detects forward/backward tilt, shown by arrows  310  of  FIG. 5 , and left/right tilt, shown in the bottom view of  FIG. 2  as arrows  312 . The sensor also responds to linear accelerations, such as those resulting from shaking the device. Typically, the tilt sensor has a response curve both in the forward/back direction and left/right direction with the form: 
                     Angle     =       sin     -   1       ⁡     (       T   -     T   c       k     )               EQ.  1               
where T is the tilt sensor value, T c  is the sensor value at 0° tilt, and k is a gain parameter. In embodiments where the sensor cannot detect the sign of the gravity vector, it is unable to determine if the user is holding the device with the display facing up or down. Gravity switch  282  of  FIG. 1  is thus provided in some embodiments to indicate whether the display is facing the ground. In other embodiments, a three-axis accelerometer is used to provide the sign of the gravity vector.
 
     In addition, the tilt sensor does not respond to rotation about an axis running from the front to the back of the mobile device. Thus, the tilt sensor is unable to sense the spinning of the mobile device on its back when laid on a flat table. Digital magnetic compass  284  of  FIG. 1  is thus provided in some embodiments to indicate this type of rotation. In other embodiments, solid state gyros are used instead of the compass. In further embodiments, a multiple axis magnetometer may be used in lieu of the digital compass, and combined with the tilt sensor values, to improve the robustness of the sensed compass direction. 
     When present, gravity switch  282  and digital compass  284  are also internal to mobile devices  200  and  701 . They are not shown in  FIGS. 3 and 7  to reduce the complexity of  FIGS. 3 and 7 . 
     Note that the additional input devices of  FIG. 1  do not all have to be present under the present invention. Different embodiments of the invention will use different numbers of and different combinations of these additional sensors. Further, additional sensors may be added without affecting the functions of the sensors discussed in the present application. 
     Transmitter  264  and receiver  266  of proximity sensor  262  are shown in  FIGS. 3 and 7 . In the embodiment of  FIG. 3 , transmitter  264  is shown below and to the right of receiver  266 , and both the transmitter and receiver are located at the top front of mobile device  200 . 
     Under one embodiment, a timer  265  drives transmitter  264  at 40 kilohertz and transmitter  264  is an infrared light emitting diode with a 60° beam angle. Under such embodiments, receiver  266  is also an infrared receiver that is capable of operating at the same frequency as transmitter  264 . The light produced by transmitter  264  bounces off objects that are near mobile device  200  and the reflected light is received by receiver  266 . Receiver  266  typically has an automatic gain control such that the strength of the received signal is proportional to the distance to the object. In a further embodiment, multiple light emitting diodes with different beam angles may be combined to improve sensor response to both distant objects (using a narrow collimated beam angle, e.g. 5°) as well as objects that are not directly in front of the sensor (using a wide beam angle). 
       FIG. 9  shows a response curve for one embodiment of the proximity sensor. In  FIG. 9 , the sensor value is shown along horizontal axis  902  and the actual distance to the object is shown along vertical axis  904 . The graph of  FIG. 9  is divided into three ranges. Range  906  extends from a distance of approximately 27 centimeters to infinity and indicates that no objects are within range of mobile device  200 . Range  908  extends from approximately 7 centimeters to 27 centimeters and indicates that at least one object is within range of mobile device  200 . Readings in third range  910 , which extends from 7 centimeters to 0 centimeters, are considered to be close to mobile device  200 . The response curve of  FIG. 9  is described by the following equation: 
                     Z   cm     =     k       (       p     p   max       -   c     )     α               EQ.  2               
where z cm  is the distance in centimeters to the object, p is the raw proximity reading, p max  is the maximum sensor reading, c is a constant, α is a nonlinear parameter (0.77 in one embodiment), and k is a gain factor.
 
     Under one embodiment, the power consumed by proximity sensor  262  is limited by pulsing transmitter  264  a few times a second when the user is out of range, or by reducing the duty cycle of timer  265 . 
     In other embodiments, IR receiver  266  generates a digital signal instead of the analog signal shown in  FIG. 1 . The digital signal provides a representation of the transmitted signal. However, as the distance between the device and the user increases, the number of errors in the digital signal increases. By counting these errors, PIC  252  is able to determine the distance between the user and the device. 
       FIG. 10  provides a block diagram of the software components of one embodiment of the present invention. In  FIG. 10 , a context information server  1000  receives the sensor data from serial port  250  of  FIG. 1 . 
     Context information server  1000  acts as a broker between the sensor values received by the microprocessor  252  and a set of applications  1002  operating on mobile device  1000 . Context information server  1000  continuously receives sensor data packets from PIC  252 , converts the raw data into a logical form, and derives additional information from the sensor data. 
     Applications  1002  can access the logical form of information generated by registering with context information server  1000  to receive messages when a particular context attribute is updated. This logical form is referred to as a context attribute. Such context attributes can be based on the state of one or more sensors as well as past states of the sensors, or even anticipated (predicted) future states. Tables 1, 2, 3 and 4 below provide lists of the context attributes that an application can register to receive. In the description column of each table, specific values for the variables are shown in italics. For example, the DISPLAYORIENTATION variable can have values of flat, portrait, landscape left, landscape right, or portrait upside down. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Group 
                 Context Variable 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 Touch 
                 HoldingLeft 
                 Binary 
               
               
                   
                   
                 HoldingRight 
                 indication of 
               
               
                   
                   
                 Holdingback 
                 contact with 
               
               
                   
                   
                   
                 touch sensor 
               
               
                   
                   
                 LeftTouchState 
                 Degree of 
               
               
                   
                   
                 RightTouchState 
                 touching: 
               
               
                   
                   
                 BackTouchState 
                 OutOfRange, 
               
               
                   
                   
                   
                 Inrange, Close 
               
               
                   
                   
                 Holding&amp;Duration 
                 Whether or not 
               
               
                   
                   
                   
                 the user is 
               
               
                   
                   
                   
                 holding the 
               
               
                   
                   
                   
                 device and for 
               
               
                   
                   
                   
                 how long 
               
               
                   
                   
                 TouchingBezel&amp; 
                 Whether user is 
               
               
                   
                   
                 Duration 
                 touching screen 
               
               
                   
                   
                   
                 bezel and for 
               
               
                   
                   
                   
                 how long 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Group 
                 Context Variable 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 Tilt/ 
                 TiltAngleLR, 
                 Left/Right and 
               
               
                   
                 Accelerometer 
                 TiltAngleFB 
                 Forward/Back 
               
               
                   
                   
                   
                 tilt angles in 
               
               
                   
                   
                   
                 degrees relative 
               
               
                   
                   
                   
                 to screen 
               
               
                   
                   
                   
                 orientation 
               
               
                   
                   
                 TiltGravityFb 
                 Absolute linear 
               
               
                   
                   
                 TiltGravityLr 
                 acceleration 
               
               
                   
                   
                 TiltAbsAngleFb 
                 Absolute tilt 
               
               
                   
                   
                 TiltAbsAngleLr 
                 angle 
               
               
                   
                   
                 GravityDir 
                 Facing up or 
               
               
                   
                   
                   
                 down 
               
               
                   
                   
                 DisplayOrientation, 
                 Flat, Portrait, 
               
               
                   
                   
                 Refresh 
                 LandscapeLeft, 
               
               
                   
                   
                   
                 LandscapeRight, 
               
               
                   
                   
                   
                 or Portrait- 
               
               
                   
                   
                   
                 UpsideDown. A 
               
               
                   
                   
                   
                 Refresh event is 
               
               
                   
                   
                   
                 posted if apps 
               
               
                   
                   
                   
                 need to update 
               
               
                   
                   
                   
                 orientation 
               
               
                   
                   
                 HzLR, MagnitudeLR, 
                 Dominant 
               
               
                   
                   
                 HzFB, MagnitudeFB 
                 frequency and 
               
               
                   
                   
                   
                 magnitude from 
               
               
                   
                   
                   
                 FFT of tilt 
               
               
                   
                   
                   
                 angles over the 
               
               
                   
                   
                   
                 last few seconds 
               
               
                   
                   
                 LookingAt, 
                 If user is 
               
               
                   
                   
                 Duration 
                 looking at 
               
               
                   
                   
                   
                 display 
               
               
                   
                   
                 Moving &amp; Duration 
                 If device is 
               
               
                   
                   
                   
                 moving in any 
               
               
                   
                   
                   
                 way. 
               
               
                   
                   
                 Shaking 
                 If device is 
               
               
                   
                   
                   
                 being shaken 
               
               
                   
                   
                 Walking, 
                 If user is 
               
               
                   
                   
                 Duration 
                 walking 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Group 
                 Context Variable 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 Proximity 
                 Proximity 
                 Estimated 
               
               
                   
                   
                   
                 distance in cm 
               
               
                   
                   
                   
                 to proximal 
               
               
                   
                   
                   
                 object 
               
               
                   
                   
                 ProximityState, 
                 Close, InRange, 
               
               
                   
                   
                 Duration 
                 OutOfRange, 
               
               
                   
                   
                   
                 AmbientLight 
               
               
                   
                   
                   
                 (when out-of- 
               
               
                   
                   
                   
                 range and bright 
               
               
                   
                   
                   
                 ambient light is 
               
               
                   
                   
                   
                 present) 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Group 
                 Context Variable 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 Other 
                 ScreenOrientation 
                 Current display 
               
               
                   
                   
                   
                 format 
               
               
                   
                   
                 VibrateOut 
                 vibrator 
               
               
                   
                   
                   
                 intensity 
               
               
                   
                   
                 Light 
                 light sensor 
               
               
                   
                   
                   
                 value 
               
               
                   
                   
                 Temperature 
                 temperature 
               
               
                   
                   
                   
                 sensor value 
               
               
                   
                   
               
            
           
         
       
     
     The context attributes of Table 1 are generated based on signals from the touch sensors, those in Table 2 are generated based on tilt sensors and the gravity switch, those in Table 3 are generated based on the proximity sensors, and those in Table 4 are posted by applications other various sensors. 
     Each context attribute is defined in a table entry that includes the following fields:
         1. A locally unique and/or globally unique identifier (GUID) for the attribute;   2. The value of the attribute;   3. The type of data that the attribute represents (e.g. integer, Boolean, etc.)   4. A read/write/read-write permission flag   5. Input, Output, or Input+Output attribute   6. Context class of attribute   7. “Dirty” data bit   8. Human-readable name and description       

     To receive messages when a context attribute is updated, a client first generates a context client. Under one embodiment, this is done using a method CreateContextClient(myHwnd) as in:
 
client=CreateContextClient(myHwnd)
 
where client is the resulting context client object and myHwnd is the window that will handle notification messages.
 
     After the context client is defined, context attributes to be provided to the client are requested using a call such as:
 
init_value=RequestNotification(client, context, usage)
 
where client is the client object created above, context is the name of the context attribute that the client wants to be updated on, and usage describes how the sensor will be used. The RequestNotification method returns the current value of the requested context attribute, which is assigned to init_value.
 
     The usage parameter can have one of four values:
         FgService: the application is using the attribute to provide a foreground service in which the user is manipulating the device to provide direct input to the device.   BgService: The application is using the sensor to provide a background service. This means the application is monitoring a signal to see if it meets criteria consistent with an anticipated pattern of user activity in which the user is not trying to provide input through their usage.   BgMonitor: The application is monitoring the context attribute to keep a record or log but is not directly providing a service based on the attribute.   StopUsing: The application is not currently using the attribute.       

     The distinction between foreground service and background service is that with a foreground service, the application is attempting to satisfy a desire that the user is explicitly requesting while with a background service, the application is attempting to perform a function that the user may or may not be aware of. For example, a user may request a foreground service of scrolling a document when a user tilts the mobile device. Thus, the user handles the mobile device in such a way as to purposefully cause scrolling. A background service may be invoked to automatically change the orientation of a display based on the readings of the tilt sensors. Thus, the user does not have to apply any attention to the device to obtain the proper orientation of the display. 
     When the server identifies a change in a context attribute, it sends a WM_COPYDDATA windows message to every window that requested notification for the context attribute. The windows message includes a parameter list lparam. The client can then retrieve the type of notification using GetNotifyType(lparam) and the value of the attribute using GetNotification(lparam, client, context). 
     When the client no longer wants notifications for an attribute, it can call a CancelNotification(client,context) method and can remove the context client from memory using DeleteContextClient(client). In addition, applications may explicitly request a change to their desired usage level(s), using a call such as:
         RequestUsageChange(client, context, usage)
 
with parameters identical to RequestNotification.
       

     By combining the requests for notification from applications with other user activity, such as switching between different applications on the mobile device, the context server can direct or withhold context notification messages from applications to simplify the sharing of sensors. 
     Under one embodiment, when context server  1000  determines that an application should not be using a context attribute due to a conflict with another application, context server  1000  will issue a UsageChange message that indicates that the application must change its usage of the context attribute to StopUsing. After the context server determines that an application may resume its use of the context attribute, it will issue a UsageChange message that indicates that the application may return to using the attribute at its requested usage level. 
     For example, if the user switches to an application that supports tilt-to-scroll and presses a button to begin scrolling, that application requests a FgService usage of the tilt attribute in a RequestNotification when the button is pressed. When this occurs, the context manager sends a UsageChange message to all other applications that have requested usage of the tilt attribute either as FgService usage or BgService usage to indicate that each of these applications are now on a StopUsing usage of the attribute. When the user indicates that scrolling is complete, the tilt-to-scroll application posts a RequestUsageChange with a usage of StopUsing. In response, context server  1000  issues a UsageChange to each of the other applications to indicate that their usage has returned to its previous value. 
     In particular, the context server sends a UsageChange message to an application telling it to StopUsing a sensor when the following criteria are met:
         1. The application is providing a BgService using a context attribute for which the active application activates a FgService;   2. The application is providing a FgService and it becomes inactive (e.g. the user switches to another application).       

     Conversely, the context server sends a UsageChange message to an application telling it to resume using an attribute at its previously requested usage level under the following conditions:
         1. The application requested a FgService usage and it becomes the active application (e.g. through explicit user activation of a new program).   2. The application requested BgService usage and an active application with FgService usage on the same attribute becomes inactive.   3. The application requested BgService usage and the active application explicitly relinquishes FgService usage on an attribute by dropping to the BgService, BgMonitor, or StopUsing usage levels.       

     Under one embodiment of the invention, even if an application ignores the UsageChange message telling it to StopUsing a context attribute, that application will stop receiving messages from the context server for that attribute. Hence, UsageChange messages provide an opportunity for application to interact smoothly with other applications, but no further explicit programmatic action is required. 
     The sensors described in  FIG. 1  have many novel uses under the present invention. Each of these uses is described below. 
     Switching Orientation Using Tilt and Movement 
     In some embodiments of the present invention, the tilt sensor is used to detect the orientation of the mobile device so that the image on the display of the mobile device may be matched to the mobile device orientation. 
       FIG. 11  provides an example of a mobile device  1100  in an upright orientation. In  FIG. 11 , the present invention displays an image  1102  of a set of text in a portrait orientation to match the orientation of mobile device  1100 .  FIG. 12  shows the same mobile device rotated counterclockwise 90°. Under the present invention, this rotation is sensed by the tilt sensors and in response, a new image  1104  of the set of text is displayed. In particular, image  1104  shows the text in a landscape view to match the new orientation of mobile device  1100 . 
     Under the present invention, the displayed image may be matched to the orientation of the device through a simple rotation of the display image or through a redrawing of the display image based on the orientation of the device and the relative dimensions of the display in that orientation. 
     A simple rotation is typically performed by using the center of the screen as the center of rotation. For such rotations, a transform of points x,y in the document to a point x′,y′ on the screen is given by equation 3:
 
 m=T·R·T   −1   EQ. 3
 
where T is a translation and R is the 2D rotation matrix for 0°, 90°, 180°, or 270°.
 
     A redrawing of the image that takes the dimensions of the display into consideration allows applications to change the contents of the image before redrawing the image. For instance, a word processing application can recalculate word wrapping based on the dimensions of the display in its new orientation. Thus, the number of words per line will change when the image is drawn in its new orientation. An example of this effect can be seen by comparing the text in image  1102  to the text in image  1104 . 
     Context information server  1000  causes the image to be refreshed by sending an appropriate notification to applications  1002 . These applications then generate a new image for the display. 
     To determine the orientation of the mobile device, most embodiments of the present invention examine both the left/right tilt of the mobile device and the front/back tilt.  FIG. 13  provides a graph showing the orientations determined by context information server  1000  for various combinations of left/right and forward/back tilt. In  FIG. 13 , left/right tilt is shown along horizontal axis  1300  and forward/back tilt is shown along vertical axis  1302 . In  FIG. 13 , there are four orientation regions  1304 ,  1306 ,  1308 , and  1310 , which are separated by deadbands  1312 ,  1313 ,  1314  and  1315 .  FIG. 13  also includes a flat area  1316  that corresponds to the mobile device being laid flat. 
     Orientation area  1304  is related to an upright portrait orientation for a mobile device such as mobile device  1100  of  FIG. 11 . This is the typical or natural way for a user to hold the mobile device. Orientation areas  1308  and  1310  are associated with a rotation of the mobile device counterclockwise and clockwise 90°, respectively. Orientation area  1306  is associated with the mobile device being rotated 180° so that is upside down. 
     Transitions between these areas nominally occur when the left/right tilt equals the forward/back tilt. As shown by deadbands  1312 ,  1313 ,  1314  and  1315 , the display does not switch immediately at these angles. Instead, there is a plus or minus 5° deadband to prevent jitter. Thus, the device must tilt through the entire deadband zone before context information server  1000  of  FIG. 10  will issue a new orientation value. In some embodiments, there is a further 0.5 second time-out. The orientation of the device must remain at the new orientation for 0.5 full seconds before the display format changes. 
     Under some embodiments of the present invention, the mobile device&#39;s touch sensor attributes are also remapped to match the orientation of the mobile device. For example,  FIGS. 14 and 15  show a tablet PC in two different orientations that are 180 degrees apart. In the orientation of  FIG. 14 , contact with touch sensor  1400  is mapped as a contact with a left touch sensor and contact with touch sensor  1402  is mapped as contact with a right sensor. In the orientation of  FIG. 15 , contact with touch sensor  1400  is mapped as contact with a right touch sensor and contact with touch sensor  1402  is mapped as contact with a left touch sensor. 
     Under one embodiment of the present invention, the orientation of the display is stabilized to avoid undesired switching of the displayed orientation. This is achieved by monitoring the degree to which the mobile device is being moved. In particular, the mobile device should experience a relatively fast motion followed by a relative stop in the motion as the tilt angle moves from one tilt orientation to another in order to change the display orientation. In one embodiment, this movement is measured as:
 
 Δx= tilt x −prevTilt x   EQ. 4
 
 Δy= tilt y −prevTilt y   EQ. 5
 
sampleEnergy=√{square root over (Δ x   2   +Δy   2 )}  EQ. 6
 
signalEnergy=signalEnergy*(1−α)+sampleEnergy  EQ. 7
 
where tiltx and tilty are current tilt values in the forward/back and left/right directions, respectively, prevTiltx and prevTilty are tilt values from the preceding sampling time, α is a decay rate which in one embodiment is 0.25 and signalEnergy is initialized to a value of 1.0.
 
     The value of the signalEnergy indicates the amount of movement that the mobile device is experiencing. Under one embodiment, the mobile device is considered to be moving when the signalEnergy exceeds an onset threshold for more than a set period of time. Under one embodiment, the onset threshold is 12.0 and the period of time is 0.2 seconds. The cessation of movement is detected when the signalEnergy drops below a cessation threshold for the same amount of time. Under one embodiment, the cessation threshold is 8.0. 
     Under this embodiment of the invention, the context server detects movement followed by cessation of movement. If the orientation of the displayed image on the screen does not match the instantaneous screen orientation (the orientation of the device), a 1 second time-out begins. After the time-out, the context server generates a message to switch the orientation of the displayed image to match the instantaneous screen orientation. Note that although a 1 second time-out was used in this embodiment, shorter or longer time-outs may be used. 
     If movement begins again during the time-out, the time-out is cancelled. If the orientation of the device changes during the time-out, the time-out, is restarted at its full duration. 
     By combining the detection of tilt with the detection of movement, the present invention reduces the probability of switching the display format by accident, or of switching the display format multiple times during a single movement. 
     To determine whether the displayed image can be oriented to match the orientation of the device, Windows XP provides a method for enumerating the available display formats that is called EnumDisplaySettingsEx. Under one embodiment, the resolution or color depth of the image can be dropped to a lower level if it is necessary for the graphics hardware to display the screen at the orientation dictated by the device. A ChangeDisplaySettingsEx method allows the context server to change the orientation of the displayed image to match the orientation of the device. 
     Orientation Preview Feedback 
     In mobile devices with larger displays, such as a tablet PC, changing the orientation of the display takes time, uses valuable computing resources, and can include a period of time when the display goes blank. Thus, it is desirable to give users feedback so that they can prevent a switch in the orientation display before it takes affect. 
     Under one embodiment of the present invention, this feedback is presented in the form of an icon that indicates the orientation of the displayed images that will be triggered if the device is kept in its current orientation.  FIG. 16  provides an example of an icon  1600  that provides this feedback. Although shown as obscuring the images below icon  1600  in  FIG. 16 , in other embodiments, icon  1600  is semi-transparent allowing everything outside of the diamond to be activated by mouse or pen input. The feedback icon may further contain links or zones that the user can click on with a mouse, stylus, or touchscreen to customize or disable the feature if desired. 
     Note that the position of the icon  1600  is defined within the previous orientation. Thus, in  FIG. 16 , the position of icon  1600  is defined by a pair of screen coordinates for a landscape orientation of the tablet PC. In addition, since icon  1600  is defined relative to the landscape orientation, it is actually rotated to match the orientation to which the displayed images will be switched. 
     The feedback icon is automatically dismissed (either immediately, or following a time-out of a few seconds) if any of the following circumstances occur:
         The user switches to another application that uses the tilt attributes.   The user sets the Tablet PC down flat.   The Tablet PC senses that it is no longer moving and the orientation of the device matches the current display orientation.   The orientation of the displayed image is switched. (Note that in one embodiment, the icon remains on the display after the switch in the orientation of the display image for some period of time, such as 3 seconds. This gives the user feedback as to why the orientation switched.)       

     When the orientation of the displayed image switches, the icon must be redefined in order for it to appear properly on the display. In particular, the location of the icon must be redefined in terms of the coordinates that are appropriate for the new display orientation. In addition, the icon no longer needs to be rotated so the non-rotated version of the icon is displayed. 
     Orientation-Specific Applications 
     Under one embodiment of the present invention, windows that are opened in a particular orientation are hidden when the orientation changes. For example, if the user opened a word processing document while the mobile device is in a landscape orientation, the document would disappear as the user rotated the device to a portrait orientation. When the device was returned to its landscape orientation, the document would reappear. 
     This technique allows users to keep more windows open on the mobile device while not cluttering the display in any one orientation. Thus, for a rectangular display, there can be four different orientations resulting in four different work spaces. In each of these work spaces, the user can have different windows open. By simply rotating the mobile device, the user can access the different work spaces and the different windows open in those work spaces, without having to click on minimized windows or icons in the display. 
       FIGS. 17 and 18  show examples of orientation-specific applications. In  FIG. 17  a word processing window  1700  is open while the device is in a landscape orientation. When the orientation is switched to a portrait orientation, the word processing window  1700  is hidden and an e-mail window  1800  is displayed. 
     Under one embodiment, the windows are hidden using the ShowWindow(SW_HIDE) Windows API call. In other embodiments, the windows are hidden by terminating the application or placing the application in hibernation. 
     In further embodiments, a single application can appear in more than one orientation work space. In such embodiments, the same window may appear in multiple work spaces or different windows, representing separate instances of the application, will be found in the displays for the various orientations. Thus, one orientation may show a first document in a word processing window while a second orientation may show a second document in the word processing window. 
     Under one embodiment, before changing the orientation of the displayed image, the windows that will be hidden when the orientation changes are removed from the display so that the user can see which windows will be lost due the change in orientation. 
     The idea of orientation-specific applications can be extended to orientation-specific tasks, which represent a collection of windows, data and applications that have been grouped together by the user. Thus, each orientation can display a separate set of selectable tasks to the user, thereby allowing the user to group the tasks and to find the tasks without increasing the amount of clutter on the display. An example of a task would be a combination of a word processing window and a billing window. 
     Although windows have been described above, any displayed item may be treated in the same way. As such, icons, menus, and backgrounds can all be orientation specific such that they only exist in selected orientations. 
     Saving Window Placements 
     When application windows are redisplayed in a new orientation, the present invention records the size and placement of the window in the previous orientation. This allows the windows to be replaced in the same position and the same size when the mobile device is returned to this position. If the position and size information were not recorded, the window may shift or change sizes due to the differences in the dimension of the display at various orientations. For example, a window that is shown in the right side of a landscape orientation may be shifted to the center and made smaller in a portrait orientation. If the position and size were not recorded as is done in the present invention, the window would be shifted to the center and appear smaller when the orientation returned to the landscape view. 
     This same technique can be applied to other items shown on the display such as icons and menus. 
     Display Contrast Adjustment 
     One problem encountered when using a tilted liquid crystal display is that as the display is tilted away from the user, the contrast of the displayed image is lessened. The present invention improves the displayed image by increasing the contrast of the display as the user tilts the display away from them. Note that this aspect of the present invention is not limited to personal information managers and may be used with any LCD device such as a pager, watch, laptop computer, tablet PC, cell phone, or stand alone LCD display. Under one embodiment, the contrast is set according to the following equation:
 
contrast= m·dA   fb   +b   EQ. 5
 
where m is a constant equal to −0.135, b is a constant equal to 5.25, dA fb  is the change from the ideal viewing angle as measured by a tilt sensor in the display, and “contrast” is the change in the contrast setting. Note that these values correspond to the software contrast settings of 1-10 available on the Cassiopeia E105 device. To prevent hysteresis, a tilt angle change of more than 3° is typically required before the contrast is adjusted.
 
     In further embodiments, the light level detected by the light sensor is also used to set the contrast and brightness such that the brightness increases as the ambient light increases and decreases as the ambient light decreases. 
     Power Management 
     Under one embodiment of the present invention, a mobile device, such as a tablet PC, places itself in a full-power mode based on how the device is being handled. In one particular embodiment, the invention uses a combination of sensors to determine whether the user wants the device to be in full-power mode. In particular, the system uses a touch sensor to determine whether the user is holding the device and a tilt sensor to determine whether the user has properly oriented the device so that it is likely they are looking at it. By using both a touch sensor and an orientation sensor, the present invention avoids placing the device in full-power mode when it is in a briefcase. 
     In one particular embodiment, the orientation for full-power mode is a left/right tilt of between plus or minus 15°, a forward/back tilt of greater than −5°, and an upright portrait orientation. If the user maintains this orientation for at least 0.5 seconds, PIC microprocessor  252  of  FIG. 1  places the device in full-power mode using power switch  280 . The required time interval can be set as desired but is used to prevent powering up due to transient signals. 
     In other embodiments, the present invention prevents a mobile device from entering an idle mode if the user is handling the device or gesturing toward the device. In idle mode, the mobile device reduces the power consumption of the device by turning off the display and/or other system components. Typically, a mobile device will enter idle mode if the user has not pressed a button or touched the screen for some period of time. Under certain types of usage, users find that the system powers down when they would rather have it remain active. For instance, this often happens when the user is reading a large amount of text or is trying to interact with someone else while periodically relating to the text. 
     Under one embodiment of the invention, the device is prevented from entering an idle mode when context information server  1000  determines that the user is holding the input device or when it determines that there is motion near the device. Such motion can be detected by changes in the output of the proximity sensor and is indicative of a user gesturing toward the device. 
     Note that this embodiment relies on motion and not just proximity. This is done to allow the device to enter idle mode when it is placed near a fixed object while it is not being used. For example, under the present invention, the device will still enter idle mode if a stack of paper is placed on top of the device. 
     Enlarge Double-Click Size 
     When the sensors detect that the user is Walking or that the Tablet is moving, the double-click thresholds are enlarged under one embodiment of the present invention to make it easier to select an object on the display. The double-click thresholds define the area on a display where a user must click twice to activate an icon or link. By increasing this area when the user is moving, the present invention makes it easier for users to successfully activate an icon or link. Similarly, system thresholds exist for distinguishing a click from a dragging (drag-and-drop) behavior, and can be enlarged with motion. 
     “Throw” to Dismiss 
     Under one embodiment of the present invention, a flinging gesture to the left or right, as if throwing the mobile device, can be sensed by the tilt sensors and can be used by an application to represent a desire by the user to dismiss a window or dialogue box, to move back to a previous page or forward to a next page, or to switch applications. 
     Tilt-a-Sketch 
     The tilt sensors in a mobile device can be used to draw on a screen. When a user tilts the mobile device, a line is drawn in the direction of the tilting. Lines can be erased by turning the mobile device upside down and shaking the device. The fact that the mobile device is upside down is detected by the gravity switch and the shaking is detected by the linear accelerometers. The tilt drawing is briefly suspended after a shake to erase so that the mobile device can be returned to its upright orientation without drawing on the screen. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.