Patent Publication Number: US-11662838-B1

Title: Information handling system stylus with power management through acceleration and sound context

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates in general to the field of portable information handling systems, and more particularly to an information handling system stylus with single power management through acceleration and sound context. 
     Description of the Related Art 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Portable information handling systems integrate processing components, a display and a power source in a portable housing to support mobile operations. Portable information handling systems allow end users to carry a system between meetings, during travel, and between home and office locations so that an end user has access to processing capabilities while mobile. Tablet configurations typically expose a touchscreen display on a planar housing that both outputs information as visual images and accepts inputs as touches. Convertible configurations typically include multiple separate housing portions that couple to each other so that the system converts between closed and open positions. For example, a main housing portion integrates processing components and a keyboard and rotationally couples with hinges to a lid housing portion that integrates a display. In a clamshell configuration, the lid housing portion rotates approximately ninety degrees to a raised position above the main housing portion so that an end user can type inputs while viewing the display. After usage, convertible information handling systems rotate the lid housing portion over the main housing portion to protect the keyboard and display, thus reducing the system footprint for improved storage and mobility. Convertible information handling systems can also include a touchscreen display that accepts end user inputs as touches at information presented by the display. 
     One tool used to interact with a touchscreen display is a stylus that writes like a pen by touching a tip at the touchscreen display. An advantage of a stylus, as opposed to a finger, is that a stylus has a more precise input point and mimics conventional pens that write ink to paper. The precision of inputs is provided by a small point of the writing tip and enhanced by transmitting a signal from the writing tip that is detected by the touchscreen display, such as a capacitive sensor that, in essence, detects near field effects. In addition, a stylus can enhance end user inputs through wireless communications with the information handling system, such as with BLUETOOTH. As an example, a stylus typically includes a push button near the tip than an end user can activate to change the writing input accepted by the information handling system, such as commanding a thicker or thinner drawn line or a different color. Other push buttons on the stylus control power and BLUETOOTH connectivity, such as commanding advertising. One difficulty with the inclusion of complex functionality and pressable buttons in a stylus is that the stylus housing should mimic a pen or other writing utility with a small round housing and minimal weight. Robust interactive buttons generally add weight and size to the housing around the button location and at an increased cost. Deploying processing capabilities in a pen-sized housing can prove difficult and expensive. In addition, the processing capability tends to have increased power draw that reduces battery life and can result in selection of larger battery sizes. One way to address this larger power draw is to sleep the stylus when not in use, however, this often introduces confusion and inconvenience to an end user who has to press a button to wake the stylus or experiences a delay in active inking while the stylus wakes. 
     Another difficulty that tends to arise with use of an active stylus is arranging to charge the battery. Including a port to interface with a charging cable tends to increase the housing size and impact the stylus usability. An alternative charging technique is to place the stylus next to a wireless charger and communicate charge wirelessly. For example, the stylus may be placed on a wireless charger pad on a desktop next to an information handling system that also receives a wireless charge. As another example, a magnet in the stylus may be used to attach the stylus to a side of an information handling system that has a wireless charger to communicate charge to the stylus. Since a stylus has a round and small shape that mimics a pen, a stylus can roll off of charging pad or fall from a magnetic attachment and become lost, such as by rolling away from the end user on the floor so that it is difficult to locate. 
     SUMMARY OF THE INVENTION 
     Therefore, a need has arisen for a system and method which supports a stylus having input buttons formed in a housing of contiguous material. 
     A further need exists for a stylus that manages power use with context derived in part by accelerometer and audio information. 
     In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for assembly of a stylus. A housing of contiguous material of a first thickness has inputs defined at portions of a second thickness of a thinner amount of material to flex in response to an end user press. The input buttons couple to a subassembly that slides into an opening of the stylus housing with a spring aligned to the area of reduced material thickness that biases the button outward. A magnet coupled to spring presses inward towards a magnetic sensor that detects increased magnetic flux at an input press. 
     A further improvement to the art is provided by accelerometer and microphone monitoring of stylus context to manage power state and stylus battery discharge. Logic stored in non-transitory memory and executed on a processing resource integrated in the accelerometer monitors for acceleration profiles based upon a static or dynamic environment of the stylus. A microphone monitors for sounds associated with certain contexts, such as rolling or falling stylus, to supplement the context determination. A variety of power consumption states are applied that reduce power draw while offering a rapid response of the stylus for end user inking. 
     More specifically, a portable information handling system processes information with processing components disposed in a planar housing, such as a central processing unit that executes instructions to process information and a random access memory that stores the instructions and information. A touchscreen display disposed on one side of the planar housing presents the information as visual images and accepts touches as inputs. A stylus having a writing tip exposed at one end of a cylindrical housing provides touch inputs at the touchscreen display in a manner that mimics a pen and with an active tip that enhances capacitive touch detection. The stylus has a single shot plastic housing formed as a cylinder with a writing tip opening at a first end and an end cap opening at an opposing second end. A subassembly with a circuit board, a writing tip and an end cap slides into the housing at the second end to expose the writing tip at the first end and enclose the circuit board with the end cap at the second end. The circuit board includes first and second input buttons that align with portions of the housing having a reduced thickness with a leaf spring of each input button pressing outward at the area of reduced thickness so that an input press flexes the housing material inward to push the leaf spring towards the circuit board. A magnet coupled to the leaf spring has closer proximity to a magnetic sensor, such as magnetometer or Hall sensor, when a press is made at the input button so that an input is detected at the circuit board. The circuit board has a main processing resource, such as an MCU, an accelerometer and an audio processor interfaced with a microphone. The accelerometer applies acceleration profiles using an integrated processing resource to manage power, such as waking and sleeping the main processing resource and radio based upon detected accelerations and other context monitored with the accelerometer processing resource while the main processing resource and the radio sleep. Similarly, the microphone applies audible profiles, such as the sound of a rolling stylus or a stylus to ground impact, to monitor a context of the stylus. Wake times for the main processing resource and wake events may be managed by GPIO commands from the accelerometer and/or microphone so that the main processing resource can analyze context when awake and reset the acceleration and sound profiles used by the accelerometer processing resource when the main processing resource sleeps. 
     The present invention provides a number of important technical advantages. One example of an important technical advantage is that an information handling system stylus assembles a subassembly into a housing with a simple sliding motion to have input buttons of the subassembly aligned with thin material portions of the housing. The thin material flexes slightly to provide an input signal by pressing a magnet towards a magnetic sensor with minimal wear on the housing material over time, thus providing a simple, reliable and robust input button. The stylus manages power draw in an efficient manner by reference to acceleration and audio profiles associated with contexts having predictable behaviors. For example, a static environment with fewer accelerations might minimize power draw in an idle state by relying only on logic executing in a processing resource of an accelerometer while a dynamic environment might use more frequent wakes to analyze context and reset the acceleration and audio profiles. This provides minimal battery draw yet offers rapid response in the event of an end user initiating use of the stylus to ink on a touchscreen display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element. 
         FIG.  1    depicts an exploded perspective view of a portable information handling system and stylus; 
         FIG.  2    depicts a front perspective view of the stylus; 
         FIGS.  2 A and  2 B  depict side cutaway views of the stylus configured to accept inputs at an input button; 
         FIG.  3    depicts an exploded view of the stylus and a subassembly configured to slide into the stylus; 
         FIG.  4    depicts a flow diagram of a process to manage an input press at the stylus button; 
         FIG.  5    depicts a flow diagram of a process to manage release of an input button at the stylus; 
         FIG.  6    depicts a variety of acceleration profiles associated with stylus movement and detected by an accelerometer in conjunction with other context; 
         FIG.  7    depicts a flow diagram of a process for managing stylus power based upon acceleration profiles and context; 
         FIGS.  8 A and  8 B  depict examples of sound monitoring with a stylus microphone to detect stylus context; and 
         FIG.  9    depicts a flow diagram of a process for managing stylus power and position reporting based upon microphone and acceleration detection of various contexts. 
     
    
    
     DETAILED DESCRIPTION 
     A portable information handling system stylus has a durable structure with integral input buttons coupled to a subassembly and interacting through a thin housing portion, along with battery power management through acceleration and sound context. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. 
     Referring now to  FIG.  1   , an exploded perspective view depicts a portable information handling system  10  and a stylus  28 . Portable information handling system  10  is built in a planar housing  12  having a touchscreen display  14  coupled on one side and exposed to accept touch inputs by an end user. A motherboard  16  couples within housing  12  to interface processing components that cooperate to process information. For instance, in the example embodiment, a central processing unit (CPU)  18  executes instructions to process information in cooperation with a random access memory (RAM)  20  that stores the information and instructions. A solid state drive (SSD)  22  has non-transitory memory that stores the information and instructions during power down, such as an operating system that is retrieved to RAM  20  at system boot. An embedded controller  24  manages physical interactions between components, such as with application of power and management of thermal constraints. Embedded controller  24  supports interactions by CPU  18  with input/output (I/O) devices, such a keyboard, mouse and the touch controller of touchscreen display  14  that reports touch inputs. A wireless network interface controller (WNIC)  26  provides wireless signal communication with external devices, such as through WiFi and Bluetooth protocols. 
     Stylus  28  has a writing tip  30  extending from one end of a cylindrical housing that mimics a pen. Writing tip  30  provides a more precise point of contact at touchscreen display  14  than is available by a finger touch so that end user inputs can include writing and drawing as if on a piece of paper. In the example embodiment, writing tip  30  has enhanced touch input accuracy by outputting a signal generated from internal components that improve capacitance touch detection. The signal from writing tip  30  is generated with a battery included in stylus  28  that is periodically charged and managed by touch buttons on stylus  28  that exchange wireless commands with information handling system  10 . For example, stylus  28  has a power button that also commands Bluetooth functions, such as pairing, and an inking button that allows an end user to control line width, as an example, with touch inputs at stylus  28  that are communicated to information handling system  10 . In the example embodiment, stylus  28  has a magnetic “garage” located at one side of housing  12  so that magnetic attraction holds stylus  28  in place when not in use. A wireless charger near the garage provides a wireless power charge to stylus  28  to charge its internal battery when garaged. In this manner, stylus  28  is ready for an end user to grasp and use as desired with a full charge available to perform active capacitive writes from writing tip  30 . 
     Referring now to  FIG.  2   , a front perspective view depicts the stylus  28 . Stylus  28  is built in a cylindrical housing having a writing tip opening at one end through which writing tip  30  extends and an end cap opening at an opposing end that is covered by an end cap, as described in greater detail below. A first input button  32  is located proximate writing tip  30 , and a second input button  34  is located at the end opposite writing tip  30 . In various embodiments, each input button may have different controls for stylus  28 , such as adjusting inking width and/or color, turning power on and off, and managing Bluetooth advertising and pairing. In the example embodiment, stylus  28  has a cylindrical shape that includes a partially flat surface that rests against the information handling system housing when garaged. Alternative embodiments may include additional input buttons and alterations to the shape, although generally a cylindrical shape that mimics a pen, as depicted, tends to meet end user expectations for writing at a touchscreen display. In the example embodiment, input buttons  32  and  34  are manufactured contiguous with the rest of the stylus housing as a thinner material, such as with a single shot injection mold of plastic that defines a first material thickness for the housing and a second material thickness for the input buttons that is less than the first material thickness. The thinner material thickness at input buttons  32  and  34  flexes in response to a press to pass an end user input to an input button assembly within the stylus housing, such as is described below in greater depth. 
     Referring now to  FIGS.  2 A and  2 B , side cutaway views depict the stylus configured to accept inputs at an input button as indicated by the cross-sectional lines of  FIG.  2   .  FIG.  2 A  depicts a cross-sectional view of input button  34  having a thin-walled section  36  at which an end user press flexes the housing material inward and against a leaf spring  38  biasing device. Leaf spring  38  couples to a circuit board  44  under thin-walled section  36  to press upward against thin-walled section  36  for support to a neutral position when not pressed by an end user. This upward bias of leaf spring  38  helps to reduce risk of damage at the thin-walled material due to extraneous contact during normal use. A magnet  40  couples to a bottom surface of leaf spring  38  aligned vertically over a magnetometer integrated circuit  42  that measures magnetic flux, which varies based upon the vertical position of magnet  40 . Magnetometer integrated circuit  42  may include a variety of sensors that detect magnetic fields and flux, such as Hall switch or compass.  FIG.  2 B  depicts a similar arrangement for input button  32  with a leaf spring  54  biasing upwards against a thin-walled section of the housing and having a magnet  56  coupled to a lower side over a magnetometer  58  coupled to a circuit board  60 . In each case, the leaf spring is a thin metal material, such as stainless steel, assembled to the circuit board always have some upward bias working against the thin-walled housing section so that no air gap exists between the metal material and housing at the upper arc of the leaf spring. In one example embodiment, a magnetometer magnetic sensor detects movements of 0.2 mm with a resolution of 0.01 mm so that relatively small movements flexing the housing thin-walled section inward can be sensed as an input. 
     When an end user presses on input button  32  or  34  to flex the thin-walled material inward, a magnetic sensor, such as a magnetometer, detects the change in magnetic flux due to the change in distance between the magnetic sensor and magnet, which sends an input signal trigger to the circuit board. When the end user releases the input button, the leaf spring and magnet return to the biased outward neutral position so that the magnetic sensor detects reduced magnetic flux and ceases the trigger signal to the circuit board. The thin-walled material at each input button flexes a small but perceptible amount of movement in response to an end user push. The movement is reinforced by the outward biasing of the leaf spring to provide an end user with additional feedback that an input has been completed. In  FIG.  2 A , an LED  52  is illuminated to indicate an input as further feedback to the end user. LED  52  is located below thin-walled material  36  where it extends over end cap  50  coupled at the end of the stylus housing. In the example embodiment, end cap  50  has an opening that allows external sounds to reach a microphone integrated circuit  48 , such as a MEMS type microphone, that provides detected sounds to an audio integrated circuit  46 , as is described in greater detail below. 
     Referring now to  FIG.  3   , an exploded view depicts the stylus  28  and a subassembly  64  configured to slide into the stylus housing  62 . Subassembly  64  is a structure that holds one or more circuit boards  44  ready to assemble into housing  62 . Housing  62  is a body of contiguous material manufactured with a single shot of plastic material having thinner material at input buttons  32  and  34 . In the example embodiment, the location of input buttons  32  and  34  are highlighted with a slight indent in the exterior surface to help an end user see and feel the location of the input buttons. Input button  34  extends past the end of housing  62  at the end cap opening to overlap end cap  50  when subassembly  64  inserts into housing  62  with writing tip  30  in the end cap opening, as depicted. Subassembly  64  includes leaf springs  38  and  54  built in locations to align with the thinner material of housing  62  at inputs buttons  34  and  32  respectively. A processing resource  66  coupled to circuit board  44  provides processing functions, such as execution of instructions to control stylus functions and radio communications, such as with a radio system on chip (SOC) solution. An accelerometer  68  senses accelerations, such with a three axis gyroscope configuration. When subassembly  64  fully inserts into housing  62 , end cap  50  engages with the inner circumference of housing  62  to hold subassembly  64  in position so that writing tip  30  extends out the writing tip opening in positions to support stylus writing. In one example embodiment, end cap  50  may be held in place with additional coupling devices, such as screw or adhesive. 
     Referring now to  FIG.  4   , a flow diagram depicts a process to manage an input press at the stylus. The process starts at step  70  with a finger or thumb press at an input button defined by an area of reduced material thickness in a contiguous material housing body. At step  72  the thin-walled portion of the housing flexes inward in response to the end user press. At step  74 , the metal spring biasing outward at the inner side of the thin-walled housing portion is overcome to move inward. Although the example embodiment depicts a leaf spring, other types of springs or biasing devices may be used to bias outward at the thin-walled portion and change the position of the magnet in response to an end user press. At step  76 , the magnet mounted on the leaf spring moves inward with the leaf spring and towards the magnetometer integrated circuit to increase the magnetic flux in proximity to the magnetometer. At step  78 , the magnetometer integrated circuit detects the increased magnetic flux strength when the magnet moves in closer proximity. As is described above, other types of magnetic sensors may be used such as a Hall sensor. At step  80 , when the detected magnet flux exceeds a defined limit an input trigger command is provided to the stylus circuit board and processing resource, such as to start a debounce timer that validates the input. 
     Referring now to  FIG.  5   , a flow diagram depicts a process to manage release of an input button at the stylus. At step  82  the end user finger or thumb releases pressure at the input button thin-walled section. At step  84 , the leaf spring biases the thin-walled portion outward to the neutral position. At step  86  the leaf spring returns to the neutral position, raising the magnet at the bottom side of the leaf spring away from the magnetometer. At step  88  the magnet mounted on the bottom side of the leaf spring is raised and moved out of proximity to the magnetometer to reduce the magnetic flux below the strength associated with detection of the input. At step  90 , the magnetometer detects reduction of the magnetic flux strength when the magnet moves a predetermined distance from the magnetometer. At step  92 , the magnetometer integrated circuit responds to the reduced magnetic flux by sending a command to the circuit board and processing resource, such as a GPIO debounce signal that completes a timer detecting whether the input button press was sufficient to command an input. In one example embodiment, completion of an input may command illumination of an LED, such as the LED located at the end cap. 
     Referring now to  FIG.  6   , a variety of acceleration profiles are depicted that are associated with stylus movement and detected by an accelerometer in conjunction with other context. The stylus stores acceleration profiles associated with the different contexts in non-transitory memory, such as flash memory integrated in an accelerometer, and compares the sensed accelerations against the acceleration profiles, as shown by the example sensed acceleration axes  108 , to manage a power consumption state of the stylus so that stylus battery life is enhanced. As an example, stylus power is consumed in an active state by writing tip active inking at approximately 100 to 150 microamps, by a Bluetooth processing resource, such as a SOC, in an idle mode at approximately 10 to 20 microamps and by an accelerometer at 8 to 9 microamps. In the example embodiment, a processing resource and non-transitory memory of the accelerometer execute logic that monitors the acceleration profiles so that the main processing resource and inking resources can sleep or even have power cutoff to avoid all power dissipation when the stylus is not in use. For instance, the stylus accelerations are tracked in x, y and z axes and compared against the acceleration profiles to determine when and how the main processing resource and inking are powered. In the static pen test  100 , a lack of accelerations confirms the sleep state so that only accelerometer power is applied and the accelerometer logic may monitor for movement at increased time intervals. In the pen attached to stylus state  102 , a confirmation of the stylus in a garaged position is an indication of a context associated with non-use of the stylus. The garaged state may be confirmed by detection of a charge applied to the stylus, such as with wireless charging, or a proximity detected with a magnet in the information handling system in proximity to a Hall sensor of the stylus. Alternatively, a physical switch or physical coupling of the stylus to the information handling system may indicate the garage state. In addition, the garage state may include a coupling to a different physical device rather than just an information handling system, such as a pocket protector or carrying case. A pen in a bag acceleration profile  104  may include acceleration patterns that mimic a person walking or that match the acceleration of an information handling system in the bag even though the stylus is not garaged. The fiddling with the pen profile  106  has random accelerations that are small time intervals associated with end user touches at the stylus. During such active profiles, the stylus main processing resource may be commanded active to monitor stylus power consumption and more rapidly respond to end user stylus interactions, such as by commanding inking to be activated when writing. 
     As an example, use of acceleration profiles, management of stylus power states is shifted between logic executing on the accelerometer processing resource and the main processing resource based upon sensed accelerations and other context. When a stylus rests without any movement for an extend time period, such as on a desktop for greater than a minute, power to all components other than the accelerometer may be cut off completely, such as with a hard off switch managed by the accelerometer, so that only the accelerometer consumes power. In this acceleration profile, logic stored in a non-transitory memory of the accelerometer executes on a processing resource integrated in the accelerometer to monitor for stylus movement and, in the meanwhile, manage a minimum power consumption. When movement is detected, the stylus may wake to a standby power state that provides main processing resource functions to perform a greater analysis of context or the accelerometer processing resource may be used until an end user active state is deemed appropriate. In some situations, a lack of movement for an extended time period may result in the accelerometer commanding a hard off by cutting off power draw from the battery, although this power state will generally need recovery by an end user input, such as pressing a power button. 
     Once the accelerometer detects motion to wake the stylus from the sleep state, the context is determined and applied to manage power at the stylus. In one example embodiment, the context is broken into a static environment and a dynamic environment. In a static environment, such as when the stylus rests on a desktop surface, the stylus sleeps with accelerator-only monitoring until motion is detected. When motion is detected, the stylus comes to a full active state with the main processor and inking active, and monitors for normal use for a one minute period, such as touches at the writing tip and accelerations associated with end user writing with or handling of the stylus. The stylus remains awake until the context indicates a static environment and no accelerations are detected for one minute, after which the stylus sleeps again in an accelerometer-only monitoring mode. In a dynamic environment, accelerations are detected without actual use of the stylus in an active write mode, such as detection of inking by the writing tip. As an example, an end user fiddling with the stylus or packing the stylus in a backpack where it bounces around will create a good number of accelerations not associated with normal use. In such a dynamic situation, extending battery life of the stylus relies upon discernment of situations that will result in active stylus inking. Further, anticipating active stylus inking provides a rapid response so that the stylus is prepared to write when the end user desires to write. In a dynamic environment with accelerator-only monitoring, at initial detection of an acceleration the stylus is woke to a standby state as above and a check is made to determine if the stylus is garaged, such as by checking to determine if a wireless charger is present. When the stylus is garaged, dynamic accelerations that match a walking profile may indicate that the stylus is in a backpack so that the stylus may wake less frequently to check for use, thus reducing power consumption and allowing logic of the accelerometer integrated processing resource to manage power. Although the example embodiment wakes to a full standby state to use the main processing resource to determine if the stylus is garaged, in an alternative embodiment a GPIO from a charger or a Hall sensor directly to the accelerometer may be used so that the accelerometer logic can determine whether the stylus is garaged without waking the main processing resource. 
     In a dynamic environment, when a garaged status is not detected, the stylus applies logic in an accelerometer only mode that helps to maintain reduced power consumption where the stylus is not in active use yet remain available to quickly respond when an end user initiates inking. If the stylus is not garaged, an initial standby state is commanded with the main processing resource active to analyze motion, such as identifying an acceleration profile associated with walking or fidgeting. If any context indicates active use of the stylus by an end user, such as pressure on the writing tip or button presses, the stylus remains in the standby state ready to initiate inking. In the dynamic environment with a context of active use, the stylus may apply more frequent checks in the standby state to detect active use before commanding a sleep state after a predetermined time. If a predetermined time passes without context indicating inking by an end user, the stylus sets a “shaking” bit of the accelerometer to indicate a dynamic environment and then commands a standby mode with accelerometer only monitoring. When the shaking bit is set, a variety of wake logics may be applied based upon the context at the time that the shaking bit is set, such as a walking profile or a fiddling profile. In one example embodiment, a wake interval of three seconds is set in the dynamic environment to check for active use and then monitoring with accelerometer only is commanded. Other intervals and types of monitoring may be used, such as by setting the dynamic environment acceleration profile in the accelerometer and monitoring with the accelerometer only unless a change in the acceleration profile is detected, such as walking changing to rest. At the detection of a change of the acceleration profile by the accelerometer logic, a wake of the stylus main resource may be performed to determine the context and reset the type of acceleration profile monitored by the accelerometer only logic. In this way, monitoring by the accelerometer detects changes to the acceleration profile with a low power consumption and wakes the main processing resource to reprogram the accelerometer for the next acceleration profile to monitor so that power consumption is reduced while stylus context is monitored with greater accuracy. 
     Referring now to  FIG.  7   , a flow diagram depicts a process for managing stylus power based upon acceleration profiles and context. The process starts at step  110  with the stylus in a shut down state except for monitoring by logic executing on a processing resource integrated in the accelerometer. At step  112  a determination is made of whether the stylus is shaking and, if no accelerations of at least a predetermined minimum are detected, the process returns to step  110  to continue in the shut down state. If accelerations are detected at step  112 , the process continues to step  114  to wake pen functions all on in a sleep state, for example by waking the main processor while sleeping the ink function, and to step  116  to determine if the stylus is attached to a tablet information handling system or otherwise garaged. When the stylus is garaged, the logic assumes a static environment of nonuse and, at step  118  monitors the context to confirm the nonuse. At step  120  after nonuse, the stylus enters the shut down state with monitoring performed by logic executed on the accelerometer processing resource with logic stored in non-transitory memory accessible by the accelerometer processing resource. During the ten seconds of monitoring, the stylus main processing resource may program the context and monitoring logic applicable to the accelerometer processing resource. For instance, the wake interval for a garaged stylus may be increased so that power consumption is reduced and the logic may simply check to confirm a garage status at each wake so that a minimal power consumption is used until the stylus leaves the garaged status, at which time accelerations may be monitored or a wake to reprogram the context may be performed. 
     If at step  116  the stylus is not garaged, such as with attachment to the tablet information handling system, the process continues to step  122  to wake the stylus functions in a sleep state. For example, the stylus main processing resource and radio wake to check the stylus context, such as the presence of a tablet information handling system radio or a press by the writing tip on a touchscreen display. At step  124 , if the stylus does not have a context of active use, such as inking, the process continues to step  126  to determine if a “shaking” bit of the stylus is set to zero. The shaking bit indicates whether the stylus has been in a sleep mode with a static or dynamic environment. If the shaking bit is set to one, the process continues to step  128  to power down the stylus for three seconds and then return to step  110  to continue monitoring for active use. The wake interval of three seconds with monitoring only by the accelerometer provides a minimal drain on battery charge and sufficient monitoring that will capture a change in context to an active user state so that the stylus is prepared for use when an end user starts inking. If at step  126  the shaking bit is set to zero, the process continues to step  142  to sleep the stylus for three seconds to ensure the dynamic environment nonuse state, and then the shaking bit is set to one at step  144 . At step  146  the stylus is placed in the shut down state so that monitoring continues at step  110  with the shaking bit set at one. 
     If at step  124  the stylus wakes to detect a context of end user engagement with inking functions, the process continues to step  130  in a full wake state to support active use and continues monitoring active use at step  124  until stylus activity has ended. When at step  130  the stylus context indicates that stylus use is complete, such as completion of inking and a predetermined amount of time without accelerations or detection of a garaged status, the process continues to step  132  to first confirm completion of functional use with five seconds of no accelerations and then to step  134  to sleep the stylus with the accelerometer monitoring for accelerations. At step  136  the stylus is monitored for acceleration for thirty seconds, returning to step  124  until the timer indicates completion of the monitoring. If steps  124  through  134  complete for thirty seconds without further functional use of the stylus, then at step  136  the process continues to step  138  with the stylus transition to a shut down state and step  140  with the accelerometer shake bit set to zero, indicating a static environment in the shutdown state. 
     Referring now to  FIGS.  8 A and  8 B , examples depict sound monitoring with a stylus microphone to detect stylus context. The microphone in stylus provides additional information regarding context to help manage power consumption and to track stylus position and availability to an end user.  FIG.  8 A  depicts an example pen drop acceleration profile  150  in which a stylus drops and impacts a floor creating an impact noise. The pen drop profile is detectable both by a freefall detection of the accelerometer and the impact acceleration. The accelerometer may wake the stylus main processing resource through a GPIO input at detection of freefall or impact accelerations. In addition, the accelerometer may wake the microphone so that the sound of the impact is detected and an indication of the impact is radio communicated back to the tablet information handling system, thus allowing the system to track the location at which the impact occurred. In addition, orientation determined by the accelerometer may be captured at the impact to determine if the stylus writing tip sustained the force of the impact, such as when the writing tip is oriented downward at the time of the impact.  FIG.  8 B  depicts an example pen rolling off acceleration profile  152  in which a stylus rolls on a desktop surface to generate a rolling sound picked up by the microphone. In both the impact and the rolling scenarios, the microphone may be used to detect the context with or without the accelerometer. For instance, the microphone may monitor sounds in a low power mode with an integrated processing resource that wakes the rest of the stylus if a detected sound matches an impact or rolling sound pattern. Alternatively, the accelerometer may wake the microphone when a freefall or a rolling acceleration profile is detected to help confirm the context of the stylus. In alternative embodiments, other types of sounds may be monitored by the microphone to determine the stylus context, such as the sound of typing as an indication of end user engagement with an information handling system, the sound of multiple voices to indicate a multiperson conversation, such as may indicate sharing of a tablet view and anticipated stylus use, or the sound of one voice to indicate a telephone conversation. 
     Referring now to  FIG.  9   , a flow diagram depicts a process for managing stylus power and position reporting based upon microphone and acceleration detection of various contexts. The process starts at step  176  with the stylus rolling across an uneven surface, such as a desktop. At step  178 , the sound generated by the rolling stylus is detected by the stylus microphone. Note that the microphone may monitor for the sound with the stylus in a sleep state, may be awakened by the accelerometer or may detect the rolling sound during normal use. At step  180 , an artificial intelligence DSP of the microphone or its audio processor process the sound characteristics to determine the rolling sound. At step  182 , the accelerometer in the stylus detects the changes in orientation due to rolling, such as with a gyroscope defined by accelerations detected with accelerometers aligned along three axes. At step  184 , the stylus main processing resource processes both the audio and acceleration data to determine the context of the stylus as rolling on a desktop surface. In response to the detected context, at step  186  the main processing resource commands communication by Bluetooth radio to the tablet information handling system. At step  188 , the Bluetooth logic on the tablet information handling system communicates to an application of the information handling system regarding the stylus context so that the position of the system can be stored and the end user can be alerted to the unstable position of the stylus. 
     At step  190  of the example embodiment, the stylus continues to roll until it falls from the desktop. As an alternative, at step  160 , the pen may accidentally detach from a garaged state at the tablet information handling system to fall without first rolling on the desktop surface. In both embodiments, at step  160  a freefall acceleration state may be detected at the accelerometer and communicated by Bluetooth to the tablet information handling system. Further, the freefall state may generate a GPIO signal to wake the stylus so that the main processing resource, such as an MCU, is available to process context information. At step  162  the stylus hits the floor with a resulting change from a freefall acceleration state to a high g-force reading and an impact that creates an impact sound. At step  164  the impact sound generated by the stylus hitting the floor is captured by the microphone and stored in local memory. At step  166 , an audio artificial intelligence DSP processes the sound captured by the microphone and analyzes the characteristics to determine that the sound is the stylus striking a hard surface. At step  168 , the accelerometer of the stylus picks up and stores acceleration and orientation information while the stylus is in freefall and at impact. At step  170  the stylus processing resource analyzes both the acceleration and audio information to determine that the stylus has fallen to the floor and the orientation of the stylus at impact. As an example, an orientation at impact of the writing tip down can indicate a risk of damage to the writing tip so that the stylus can provide a message to the tablet information handling system regarding this risk. At step  172  the stylus processing resource communicates a message to the Bluetooth radio regarding the stylus event. At step  174 , the Bluetooth radio communicates to the tablet information handling system to report the stylus falling event so that the system can track the position at which the fall took place and any potential damage based upon the orientation of the stylus at impact. 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.