RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. patent application Ser. No. 11/385,984, filed Mar. 20, 2006, entitled “METHOD AND APPARATUS FOR AUTOMATIC POWER-UP AND POWER-DOWN OF A COMPUTER SYSTEM BASED ON THE POSITIONS OF AN ASSOCIATED STYLUS AND/OR HINGE,” naming Regis Nicolas and Neal Osborn as inventors, assigned to the assignee of the present invention, and having attorney docket number PALM-3024.CON2, which is a continuation of U.S. patent application Ser. No. 11/125,543, filed May 9, 2005, now U.S. Pat. No. 7,046,237, entitled “METHOD AND APPARATUS FOR AUTOMATIC POWER-UP AND POWER-DOWN OF A COMPUTER SYSTEM BASED ON THE POSITIONS OF AN ASSOCIATED STYLUS AND/OR HINGE,” naming Regis Nicolas and Neal Osborn as inventors, assigned to the assignee of the present invention, and having attorney docket number PALM-3024.CON, which is a continuation of U.S. patent application Ser. No. 09/522,274, filed Mar. 9, 2000, now U.S. Pat. No. 6,924,791, entitled “METHOD AND APPARATUS FOR AUTOMATIC POWER-UP AND POWER-DOWN OF A COMPUTER SYSTEM BASED ON THE POSITIONS OF AN ASSOCIATED STYLUS AND/OR HINGE,” naming Regis Nicolas and Neal Osborn as inventors, assigned to the assignee of the present invention, and having attorney docket number PALM-3024. These applications are incorporated herein by reference in their entirety and for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    As the components required to build a computer system have reduced in size, new categories of computer systems have emerged. One of the new categories of computer systems is the “palmtop” computer system. A palmtop computer system is a computer that is small enough to be held in the hand of a user and can therefore be “palm-sized.” Most palmtop computer systems are used to implement various Personal Information Management (PIM) applications such as an address book, a daily organizer and electronic notepads, to name a few. Palmtop computers with PIM software have been know as Personal Digital Assistants (PDAs). 
         [0003]    Data entry on a palmtop computer has been a challenge. Since palmtop computer systems are very small, full-sized keyboards are generally not efficient input devices. Palmtop computers using keyboards have keyboard devices that are so small that a user cannot touch-type. Furthermore, to use a keyboard device, a user must either place the palmtop computer system down onto a flat surface, so the user can type with both hands, or the user holds the palmtop computer system with two hands and types with thumbs only. 
         [0004]    Instead of a mechanical keyboard device, some palmtop computers utilize a touch screen and display an image of a small keyboard thereon. When a particular button is pressed or tapped, a small keyboard image is displayed on the display screen. The user then interacts with the on-screen small keyboard image to enter characters, usually one character at a time. To interact with the displayed keyboard image (e.g., “virtual keyboard”), the user taps the screen location of a character with a pen or stylus. That corresponding character is then recognized and added to a data entry field, also displayed on the screen. However, for experienced users, the virtual keyboard input system can be a tedious input process. 
         [0005]    Instead of using a mechanical keyboard device or a displayed keyboard, many palmtop computers employ a pen and a digitizer pad as an input system. The pen and digitizer pad combination works well for palmtop computers because the arrangement allows a user to hold the palmtop computer system in one hand while writing with the pen onto the digitizer pad with the other hand. 
         [0006]    A number of palmtop computer systems that rely on the pen and digitizer pad combination as the primary means of input have been introduced to the market. Most of these pen-based palmtop computer systems provide some type of handwriting recognition system whereby the user can write words and letters on the digitizer pad with a stylus. The palmtop computer system then converts the user&#39;s handwriting into a machine readable format such as ASCII code characters. Examples of pen-based palmtop computer systems that provide handwriting recognition include the Apple Newton (trademark) device and the Tandy Zoomer (trademark) device. 
         [0007]    Digitizers have eliminated the need for a mechanical keyboard device. Therefore, palmtop computer systems are readily portable and can easily be carried on or near the user, e.g., in a pocket, purse or briefcase. Since they can be carried by a user, the user has many opportunities to use the palmtop computer during the day. Since the palmtop computer is typically battery operated, it is recommended to turn off the computer at the completion of each separate use. As such, each time the palmtop is used, an on/off button is typically pressed to turn on power to the computer system, including the display device. Therefore, each time the palmtop computer is to be used, the on/off button is pressed and after use the on/off button is pressed again to turn off the palmtop computer. The more times the computer is used, the more times the on/off button needs to be pressed to gain access to the palmtop computer. If the palmtop computer is being used merely to access (or amend or transmit) a small bit of information and then turned off, the process of pressing the on/off button twice can be a substantial amount of the user&#39;s task just to obtain or amend the desired information thereby rendering tedious the use of the computer. 
         [0008]    Users always want easier ways and mechanisms to access information on the palmtop computer. Any improvement that reduces the user&#39;s repetitive tasks in obtaining information and making use of a palmtop computer system is open to wide consumer acceptance. Therefore, it would be advantageous to make easier and less tedious the user&#39;s tasks in accessing information from a palmtop computer system. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, what is needed is an improvement that reduces the number of repetitive tasks required of a user in order to obtain information and make use of a palmtop computer system. What is needed is a method and system that reduces the repetitive tasks required in turning on and turning off the palmtop computer system. The present invention provides these advantages and others not specifically mentioned above but described in the sections to follow. 
         [0010]    A method and system are described for automatic power-up and automatic power-down of a computer system based on the position and/or rotation of an associated stylus and/or hinge. In one embodiment, the computer system is a portable computer having a logic board, a display screen, a digitizer and a receiving slot for an associated stylus. The stylus is used with the digitizer in well known character recognition modes. When the stylus is removed from the receiving slot, a switch automatically turns full power onto the computer system thereby allowing a user full use of the computer without requiring an on/off button to be pressed. When the stylus is inserted back into the receiving slot, the switch automatically returns the computer to a power reduction mode where one or all of the components of the computer are powered down. Again, the power reduction mode is entered without requiring the user to press the on/off button. The switch can be made of a single detector or a dual detector combination and can be of a mechanical, electromagnetic, optical, inductive, capacitive or electrical nature. The switch and detector can also be implemented using a microswitch device. By using the position of the stylus to automatically perform power on and off functions, the repetitive tasks required to access information from the palmtop are reduced. 
         [0011]    In another embodiment, the stylus-based automatic power-up and power-down features work in concert with other power-up and power-down mechanisms of the computer, such power-on interrupts, the on/off button, and time-out power off modes. In another embodiment, the stylus is a hinge attached to a cover that can be rotated to protect the palmtop computer (like a book cover) or rotated away to use the palmtop computer (like opening a book). When rotated to cover, the switch automatically powers down the computer. When rotated out for computer use, the switch automatically powers up the computer. By using the position of the hinge to automatically perform power up and down functions, the repetitive tasks required to access information from the palmtop are reduced. 
         [0012]    More specifically, an embodiment of the present invention includes a computer system comprising: a processor coupled to bus; a memory unit coupled to the bus; a display screen coupled to the bus; a digitizer coupled to the bus; a case for supporting the processor, the memory unit, the display screen and the digitizer, the case having a slot located therein for receiving a stylus; a detector for detecting a stylus within said slot; and a switch coupled to the detector and for generating a signal to power up the processor, the display screen and the digitizer when the stylus is removed from the slot and wherein the switch is also for generating a signal to place the processor, the display screen and the digitizer into a power conservation mode when the stylus is inserted into the slot. Embodiments include a power on and power off method implemented in accordance with the above. 
         [0013]    Embodiments also include a computer system comprising: a processor coupled to bus; a memory unit coupled to the bus; a display screen coupled to the bus; a digitizer coupled to the bus; a case for supporting the processor, the memory unit, the display screen and the digitizer, the case having a slot located therein for receiving a hinge attached to a protective cover; a detector for detecting the rotational positions of the hinge within the slot; a switch coupled to said detector and for generating a signal to automatically power up the processor, the display screen and the digitizer when the hinge is rotated such that the cover is not laid over the display screen and wherein the switch is also for generating a signal to automatically place the processor, the display screen and the digitizer into a power conservation mode when the hinge is rotated such that the cover is laid over the display screen. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is system illustration of a palmtop or “palm sized” computer system connected to other computer systems and the Internet via a cradle device. 
           [0015]      FIG. 2A  is a top side perspective view of a palmtop computer system that can be used as a platform for the automatic power-up and power-down embodiments of the present invention. 
           [0016]      FIG. 2B  is a bottom side perspective view of the palmtop computer system of  FIG. 2A . 
           [0017]      FIG. 3  is an exploded view of the components of the palmtop computer system of  FIG. 2A . 
           [0018]      FIG. 4  is a perspective view of the cradle device for connecting the palmtop computer system to other systems via a communication interface. 
           [0019]      FIG. 5  is a logical block diagram of the palmtop computer system in accordance with an embodiment of the present invention. 
           [0020]      FIG. 6  is a front view of a palm top computer system illustrating the display screen, digitizer regions and an exemplary menu of a text display application. 
           [0021]      FIG. 7  is a cross section of a stylus receiving slot incorporated within the casing of the portable computer system of an embodiment of the present invention and having a single proximity detector element. 
           [0022]      FIG. 8  is a cross section of a stylus receiving slot incorporated within the casing of the portable computer system of an embodiment of the present invention and having a pair of proximity detector elements. 
           [0023]      FIG. 9A  and  FIG. 9B  are steps performed by an embodiment of the present invention for automatically powering-up and automatically powering-down a computer system based on the position of a stylus. 
           [0024]      FIG. 10  illustrates a three dimensional view of a stylus receiving slot and a stylus for use in the hinge embodiment of the present invention. 
           [0025]      FIG. 11  illustrates a perspective view of the portable computer system with the hinge embodiment of the present invention. 
           [0026]      FIG. 12A  and  FIG. 12B  are steps performed by an embodiment of the present invention for automatically powering-up and automatically powering-down a computer system based on the rotation of a hinge. 
           [0027]      FIG. 13  illustrates a casing used in one embodiment of the present invention having a slot (or rail) for receiving a stylus or a cover hinge. 
           [0028]      FIG. 14  illustrates the slot (or rail) for receiving a stylus or a cover hinge and also illustrates a detector element in the slot. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    In the following detailed description of the present invention, a method and system for automatically powering-up and automatically powering-down a computer system based on the position and/or rotation of an associated stylus, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one skilled in the art that the present invention may be practiced without these specific details or with equivalents thereof. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention. 
       Notation and Nomenclature 
       [0030]    Some portions of the detailed descriptions which follow are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed on computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, computer executed step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
         [0031]    It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present invention, discussions utilizing terms such as “accessing” “processing” or “computing” or “translating” or “calculating” or “determining” or “scrolling” or “displaying” or “recognizing” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
       Exemplary Palmtop Computer System Platform 
       [0032]      FIG. 1  illustrates a system  50  that can be used in conjunction with the automatic power on and power off features of the present invention. System  50  comprises a host computer system  56  which can either be a desktop unit as shown, or, alternatively, can be a laptop system  58 . Optionally, one or more host computer systems can be used within system  50 . Host computer systems  58  and  56  are shown connected to a communication bus  54 , which in one embodiment can be a serial communication bus, but could be of any of a number of well known designs, e.g., a parallel bus, Ethernet Local Area Network (LAN), etc. Optionally, bus  54  can provide communication with the Internet  52  using a number of well known protocols. 
         [0033]    Importantly, bus  54  is also coupled to a cradle  60  for receiving and initiating communication with a palm top (“palm-sized”) portable computer system  100  of the present invention. Cradle  60  provides an electrical and mechanical communication interface between bus  54  (and anything coupled to bus  54 ) and the computer system  100  for two way communications. Computer system  100  also contains a wireless infrared communication mechanism  64  for sending and receiving information from other devices. 
         [0034]      FIG. 2A  is a perspective illustration of the top face  100   a  of one embodiment of the palmtop computer system of the present invention. The top face  110   a  contains a display screen  105  surrounded by a bezel or cover. A removable stylus  80  is also shown. The display screen  105  is a touch screen able to register contact between the screen and the tip of the stylus  80 . The stylus  80  can be of any material to make contact with the screen  105 . As shown in  FIG. 2A , the stylus  80  is inserted into a receiving slot or rail  350 . Slot or rail  350  acts to hold the stylus when the computer system  100   a  is not in use. As described more fully below, slot or rail  350  also contains switching devices for automatically powering down and automatically power up computer system  100   a  based on the position of the stylus  80 . The top face  100   a  also contains one or more dedicated and/or programmable buttons  75  for selecting information and causing the computer system to implement functions. The on/off button  95  is also shown. 
         [0035]      FIG. 2A  also illustrates a handwriting recognition pad or “digitizer” containing two regions  106   a  and  106   b . Region  106   a  is for the drawing of alpha characters therein for automatic recognition (and generally not used for recognizing numeric characters) and region  106   b  is for the drawing of numeric characters therein for automatic recognition (and generally not used for recognizing numeric characters). The stylus  80  is used for stroking a character within one of the regions  106   a  and  106   b . The stroke information is then fed to an internal processor for automatic character recognition. Once characters are recognized, they are typically displayed on the screen  105  for verification and/or modification. 
         [0036]    The digitizer  160  records both the (x, y) coordinate value of the current location of the stylus and also simultaneously records the pressure that the stylus exerts on the face of the digitizer pad. The coordinate values (spatial information) and pressure data are then output on separate channels for sampling by the processor  101  ( FIG. 5 ). In one implementation, there are roughly 256 different discrete levels of pressure that can be detected by the digitizer  106 . Since the digitizer&#39;s channels are sampled serially by the processor, the stroke spatial data are sampled “pseudo” simultaneously with the associated pressure data. The sampled data is then stored in a memory by the processor  101  ( FIG. 5 ) for later analysis. 
         [0037]      FIG. 2B  illustrates the bottom side  100   b  of one embodiment of the palmtop computer system of the present invention. An optional extendible antenna  85  is shown and also a battery storage compartment door  90  is shown. A communication interface  108  is also shown. In one embodiment of the present invention, the serial communication interface  108  is a serial communication port, but could also alternatively be of any of a number of well known communication standards and protocols, e.g., parallel, SCSI, Firewire (IEEE 1394), Ethernet, etc. In  FIG. 2B  is also shown the stylus receiving slot or rail  350 . 
         [0038]      FIG. 3  is an exploded view of the palmtop computer system  100  in accordance with one implementation. System  100  contains a front cover  210  having an outline of region  106  and holes  75   a  for receiving buttons  75   b . A flat panel display  105  (both liquid crystal display and touch screen) fits into front cover  210 . Any of a number of display technologies can be used, e.g., LCD, FED, plasma, etc., for the flat panel display  105 . The touch screen can be a digitizer. A battery  215  provides electrical power. The digitizer can be implemented using well known devices, for instance, using the ADS-7846 device by Burr-Brown that provides separate channels for spatial stroke information and pressure information. A contrast adjustment (potentiometer)  220  is also shown. On/off button  95  is shown along with an infrared emitter and detector device  64 . A flex circuit  230  is shown along with a PC board  225  containing electronics and logic (e.g., memory, communication bus, processor, etc.) for implementing computer system functionality. The digitizer pad is also included in PC board  225 . A midframe  235  is shown along with stylus  80 . Position adjustable antenna  85  is shown. The midframe  235  contains the stylus receiving slot or rail  350  and also anchors the automatic power on and automatic power off switch devices. The automatic power on and automatic power off switch devices of the present invention are located in region  510 , in one embodiment. 
         [0039]    A radio receiver/transmitter device  240  is also shown between the midframe and the rear cover  245  of  FIG. 3 . The receiver/transmitter device  240  is coupled to the antenna  85  and also coupled to communicate with the PC board  225 . In one implementation, the Mobitex wireless communication system is used to provide two way communication between system  100  and other networked computers and/or the Internet via a proxy server. In other embodiments, TCP protocol can be used. 
         [0040]      FIG. 4  is a perspective illustration of one embodiment of the cradle  60  for receiving the palmtop computer system  100 . Cradle  60  contains a mechanical and electrical interface  260  for interfacing with serial connection  108  ( FIG. 2B ) of computer system  100  when system  100  is slid into the cradle  60  in an upright position. Once inserted, button  270  can be pressed to initiate two way communication between system  100  and other computer systems coupled to serial communication  265 . 
         [0041]      FIG. 5  illustrates circuitry of computer system  100 , some of which can be implemented on PC board  225 . The computer system  100  can be used to perform character recognition processes and authentication of the present invention, e.g., processes  600  and  640  ( FIG. 13A  and  FIG. 13B ) and process  650  ( FIG. 14 ). Computer system  100  includes an address/data bus  99  for communicating information, a central processor  101  coupled with the bus  99  for processing information and instructions, a volatile memory  102  (e.g., random access memory RAM) coupled with the bus  99  for storing information and instructions for the central processor  101  and a non-volatile memory  103  (e.g., read only memory ROM) coupled with the bus  99  for storing static information and instructions for the processor  101 . Computer system  110  also includes an optional data storage device  104  (e.g., memory stick) coupled with the bus  99  for storing information and instructions. Device  104  can be removable. As described above, system  100  also contains a display device  105  coupled to the bus  99  for displaying information to the computer user. PC board  225  can contain the processor  101 , the bus  99 , the ROM  103  and the RAM  102 . 
         [0042]    Also included in computer system  110  of  FIG. 5  is an alphanumeric input device  106  which in one implementation is a handwriting recognition pad (“digitizer”) having regions  106   a  and  106   b  ( FIG. 2A ), for instance. Device  106  can communicate information (spatial data and pressure data) and command selections to the central processor  101 . System  110  also includes an optional cursor control or directing device  107  coupled to the bus for communicating user input information and command selections to the central processor  101 . In one implementation, device  107  is a touch screen device incorporated with screen  105 . Device  107  is capable of registering a position on the screen  105  where the stylus makes contact and the pressure of the contact. The display device  105  utilized with the computer system  110  may be a liquid crystal device, cathode ray tube (CRT), field emission device (FED, also called flat panel CRT) or other display device suitable for creating graphic images and alphanumeric characters recognizable to the user. In the preferred embodiment, display  105  is a flat panel display. 
         [0043]    Signal communication device  108 , also coupled to bus  99 , can be a serial port for communicating with the cradle  60 . Device  108  can also include an infrared communication port. 
         [0044]    Each of the devices shown in  FIG. 5  receives power from a battery device or other voltage source. This power can be interrupted via a switch device. In one embodiment, the switch is controlled by power on/off button  95  ( FIG. 3 ). When the switch is in power off mode, the devices of  FIG. 5  are disabled except for the RAM  102  which continues to receive power to maintain the volatile data. When the switch is on, power is restored to all of the devices of  FIG. 5 . As described in more detail below, in the present invention, the switch can be controlled by the position of stylus  80  with respect to a receiving slot and/or by the rotation of a cover hinge within the receiving slot. 
         [0045]      FIG. 6  is a front view of the palmtop computer system  100  with a menu bar  305  open displaying a pull down window having several selections that can be made by the user. Buttons on screen  105  can be selected by the user directly tapping on the screen location of the button with stylus  80 . Also shown are two regions of digitizer  106   a  and  106   b . Region  106   a  is for receiving user stroke data (and pressure data) for alphabet characters, and typically not numeric characters, and region  106   b  is for receiving user stroke data (and pressure data) for numeric data, and typically not for alphabetic characters. Physical buttons  75  are also shown. Although different regions are shown for alphabetic and numeric characters, the present invention is also operable within a single region that recognizes both alphabetic and numeric characters. Also shown in  FIG. 6  is the position of the stylus receiving slot or rail  350 . It is appreciated that while the stylus receiving slot or rail  350  is depicted on the left of the computer  100 , it can also be deployed on the right or along the top edge or along the bottom edge. 
         [0046]    It is appreciated that, in one embodiment, the digitizer region  106   a  and  106   b  is separate from the display screen  105  and therefore does not consume any display area. 
         [0000]    Automatic Power on and Automatic Power Off Using the Position of a Stylus and/or Cover Hinge 
         [0047]    In accordance with embodiments of the present invention the electronics of  FIG. 5  are selectively placed into various power modes in response to a switch circuit. However, in one embodiment, the RAM  102  is dynamic RAM and is constantly refreshed to maintain the volatile data regardless of the power mode of the remainder of computer  100 . For instance, in the full power or “power-up” mode, each of the electronic devices receives (consumes) nominal power from a voltage source (e.g., a battery). In a power conservation mode, also called “power down” mode, certain electronic devices receive less than their nominal power in order to conserve power. The power conservation mode also includes the scenario where the electronics devices are fully powered off, except for RAM  102 . The devices are commanded to be in either the power-up mode or the power-down mode by a mode signal generated by a switch circuit in accordance with the present invention. 
         [0048]      FIG. 7  illustrates a cut away cross sectional view of the stylus receiving slot or rail  350  of one embodiment of the present invention  510   a .  FIG. 7  also illustrates a switch device  410  that generates a mode signal over line  390 . The mode of the switch  410  is controlled by a detector device  420  and the modes are: stylus-in; and stylus out. Stylus in corresponds to power-down and stylus out corresponds to power-up. The detector device  420  is placed inside the stylus receiving slot or rail  350  that holds the stylus  80  when it is not in use. The detector device  420  is coupled to the switch circuit  410  and can be implemented, in one embodiment, as a microswitch. The devices of system  100  are commanded to be in either the power-up mode or the power-down mode by a mode signal generated by the switch circuit  410 . 
         [0049]    The stylus receiving slot or rail  350  is a part of the case  235  of the portable computer  100  ( FIG. 3  and  FIG. 6 ). According to this embodiment of the present invention, when the stylus  80  is inserted into slot  350  all the way, its presence becomes detected by detector  420  which generates a signal to switch  410 . The switch  410  via control signal  390  controls the components of  FIG. 5  (except the RAM) such that they are placed into a power conservation mode thereby causing computer system  100  to power down. 
         [0050]      FIG. 14  illustrates a three dimensional perspective view of the detector  420  located within the slot  350  of the casing  235  in one embodiment of the present invention. In the example of  FIG. 14 , the slot is cut open on one side (the facing side) to expose part of the stylus (or cover hinge) but could alternatively be completely cylindrical in shape. 
         [0051]    Alternatively, when the stylus  80  of  FIG. 7  is removed from slot  350 , its absence is detected by detector  420  which generates a signal to switch  410 . The switch  410  via control signal  390  controls the voltage source such that power to the components of  FIG. 5  is established thereby causing computer system  100  to power up for use. The user typically inserts the stylus  80  into slot  350  when he/she is done using computer  100  and the user typically removes the stylus  80  from slot  350  when he/she is ready to use computer  100 . By using the location of stylus  80  as a tool for automatically powering up and powering down computer  100 , the user does not have to press any on/off button  95 . This embodiment of the present invention therefore reduces the number of repetitive tasks the user has to perform in order to use computer  100 . It is appreciated that the detector device  420  can be implemented using a number of well known technologies for detecting the presence of an object, e.g., the detector device can be implemented as a mechanical detector device, an inductive device, a capacitive device, an optical detector device, an electrical device or an electromagnetic device. 
         [0052]      FIG. 8  illustrates a cut away cross sectional view of the stylus receiving slot or rail  350  in accordance with another embodiment of the present invention  510   b . In this embodiment, the detector device is implemented using two different detector elements  380   a  and  380   b . In this embodiment, the detectors not only report that the stylus  80  has been inserted into slot  350  but also that the stylus  80  is in the process of being slid into or slid out of the slot  350 . Both detector elements  380   a  and  380   b  are coupled to the switch circuit  375 . The mode of the switch  375  is controlled by detector device  380   a - 380   b  and the basic modes are: stylus-in; and stylus out. Stylus in corresponds to power-down and stylus out corresponds to power-up. In one embodiment, the stylus  80  has a metal surface and when placed into slot  350 , a circuit or connection is made through the stylus  80  between metal detectors  380   a  and  380   b . This generates a signal to switch  375  which enters the power-down mode as represented by a mode signal over line  390 . 
         [0053]    It is appreciated that detectors  380   a  and  380   b  can also be implemented using optical detector elements, mechanical detector elements, inductive detector elements, magnetic (e.g., reed relay), capacitive detector elements or electromagnetic detector elements. It is further appreciated that the stylus detectors located with slot  350  can be implemented using the input/output (I/O) rail technology described in co-pending U.S. patent application Ser. No. 09/484,086, filed on Jan. 18, 2000, by Neal Osborn, Francis Canova, Jr. and Nicholas Twyman, entitled, “Connector for Handheld Computer,” which is assigned to the assignee of the present invention and also hereby incorporated by reference. 
         [0054]      FIG. 9A  and  FIG. 9B  illustrate the logical states of a power state machine  610  implemented in accordance with an embodiment of the present invention. It is appreciated that the mode signal generated at line  390  is only one piece of information that is used to either power-up or power-down the computer  100 . At state  620 , the computer  100  is in the power-down state, e.g., the devices of  FIG. 5  are placed into a power conservation mode, except for the RAM  102  which continuously receives power. At step  625 , if an interrupt is received by the computer  100 , then state  640  is entered, otherwise state  630  is entered. At step  630 , if the on/off key  95  is pressed, then state  640  is entered because the computer is currently in the power-down state, otherwise step  635  is entered. At step  635 , if the switch (either  410  or  375 ) generates a mode signal over line  390  indicating that the stylus  80  has been removed from slot  350  then state  640  is entered, otherwise state  620  is entered. 
         [0055]    At state  640 , the computer  100  automatically is placed into the power-up state where nominal power is supplied to (consumed by) the devices of  FIG. 5 . At step  645  of  FIG. 9B  the computer remains in the power-up state. At step  650  of  FIG. 9B , if a time-out occurs within computer  100 , then state  665  is entered, otherwise state  655  is entered. A time-out occurs whenever no user activity is detected by computer  100  for a predetermined period of time. At step  655 , if the on/off key  95  is pressed, then state  665  is entered because the computer is currently in the power-up state, otherwise step  660  is entered. At step  660 , if the switch (either  410  or  375 ) generates a mode signal over line  390  indicating that the stylus  80  has been re-inserted into slot  350  then state  665  is entered, otherwise state  645  is entered. 
         [0056]    At state  665  of  FIG. 9B , the computer  100  automatically is placed into the power-down or power conservation state where all devices of  FIG. 5  except for the RAM  102  device are placed into a power conservation mode. State  620  ( FIG. 9A ) is then entered again. 
         [0057]      FIG. 10-FIG .  12 B illustrate the cover hinge embodiment of the present invention. In this embodiment, slot  350  can receive a stylus shaped device  80  that is also connected to a cover and thereby acts as a hinge for the cover.  FIG. 11  illustrates a perspective view of the system  100   d . The slot  350  is open in this embodiment (see also  FIG. 13  and  FIG. 14 ) and more closely resembles a rail thereby allowing the cover  550  to extend outside the rail  350  and rotate about the axis of the rail  350 . When the cover rotates clockwise  570 , the hinge  80  also rotates and the cover  550  is rotated away from display  105  so that the user can use the computer. Alternatively, when the cover  550  rotates counter-clockwise  560 , the hinge  80  also rotates and the cover  550  is rotated such that it is laid over display  105  to protect the facing surface of computer  100  when the user is done working on the computer. The cover  550  can be made of leather or any soft protective surface material. It is appreciated that a stylus can be inserted into a slot (similar to rail  350 ) that runs along the left hand edge of system  100   d.    
         [0058]    In this embodiment, the hinge  80  is not generally removed from the rail  350  very often but it is rather rotated. Therefore, in accordance with this embodiment of the present invention, when the cover  550  is rotated counter-clockwise such that it is laid over screen  105 , computer  100   d  automatically enters a power-down state. Alternatively, when cover  550  is rotated clockwise such that it does not lay over screen  105 , computer  100   d  automatically enters a power-up state. It is appreciated that the hinge  80  can be located on the left or right side of computer  100   d  or it can be located on the top or bottom edge of computer  100   d.    
         [0059]      FIG. 10  illustrates a detector pair  450   a  and  450   b  that can be used to detect the rotational position of the hinge  80 . On the surface of the hinge  80  is laid a circular “L” shaped metal tracing  440   a  and  440   b . Region  440   b  is a ring shaped metal piece. Region  440   a  on the other hand does not extend all the way around hinge  80 . Detector  450   b  is a metal detector that is ring shaped. Detector  450   a  is only semi-ring shaped, e.g., “C shaped,” and does not extend all the away around rail  350 . Although not shown in  FIG. 10  for clarity, the left edge of cover  550  ( FIG. 11 ) is connected to the right edge of hinge  80 . When hinge  80  of  FIG. 10  is in the position shown, but located inside rail  350 , metal area  440   b  contacts metal detector  450   b  but metal area  440   a  does not contact metal detector  450   a . Therefore, there is no electrical connection between detectors  450   a  and  450   b . In this configuration, switch  375  then generates a power-up mode signal because the cover is in the open position, e.g., not laid over display  105 . The devices of system  100  are commanded to be in either the power-up mode or the power-down mode by a mode signal generated by the switch circuit  375 . 
         [0060]    When hinge  80  is rotated clockwise  445  about ⅓ turn (e.g., the cover is closed and laid over display  105 ), metal area  440   b  contacts metal detector  450   b  and metal area  440   a  contacts metal detector  450   a . Therefore, there is an electrical connection between detectors  450   a  and  450   b . In this configuration, switch  375  then generates a power-down mode signal because the cover is in the closed position, e.g., laid over display  105 . In this manner, switch  375  is able to detect the rotational position of hinge  80 , and therefore of cover  550 . 
         [0061]      FIG. 12A  and  FIG. 12B  illustrate the logical states of a power state machine  710  implemented in accordance with the cover and hinge embodiment of the present invention. It is appreciated that the mode signal generated at line  390  is only one piece of information that is used to either power-up or power-down the computer  100   d . At state  745 , the computer  100   d  is in the power-down state, e.g., the devices of  FIG. 5 , except for the RAM  102  which continuously receives power, are placed into a power conservation mode. At step  625 , if an interrupt is received by the computer  100 , then state  765  is entered, otherwise state  755  is entered. At step  755 , if the on/off key  95  is pressed, then state  765  is entered because the computer is currently in the power-down state, otherwise step  760  is entered. At step  760 , if the switch (either  410  or  375 ) generates a mode signal over line  390  indicating that the hinge  80  has been rotated, e.g., clockwise, such that cover  550  is removed from the display  105 , then state  765  is entered, otherwise state  745  is entered. 
         [0062]    At state  765 , the computer  100   d  automatically is placed into the power-up state where nominal power is supplied to (consumed by) the devices of  FIG. 5 . At step  720  of  FIG. 12B  the computer remains in the power-up state. At step  725  of  FIG. 12B , if a time-out occurs within computer  100   d , then state  740  is entered, otherwise state  730  is entered. A time-out occurs whenever no user activity is detected by computer  100   d  for a predetermined period of time. At step  730 , if the on/off key  95  is pressed, then state  740  is entered because the computer is currently in the power-up state, otherwise step  735  is entered. At step  735 , if the switch (either  410  or  375 ) generates a mode signal over line  390  indicating that the hinge  80  has been rotated counter-clockwise such that cover  550  is laid over display  105  then state  740  is entered, otherwise state  720  is entered. 
         [0063]    At state  740  of  FIG. 12B , the computer  100   d  automatically is placed into the power-down state where the devices of  FIG. 5 , except for the RAM  102  device, are placed into a power conservation mode. State  745  ( FIG. 9A ) is then entered again. 
         [0064]    The user typically inserts the closes the cover  550  (over display  105 ) when he/she is done using computer  100   d  and the user typically opens the cover  550 , exposing display  105 , when he/she is ready to use computer  100   d . By using the rotational position of hinge  80  as a tool for automatically powering up and powering down computer  100   d , the user does not have to press any on/off button. This embodiment of the present invention therefore reduces the number of repetitive tasks the user has to perform in order to use computer  100   d.    
         [0065]    It is appreciated that in an alternative to the cover hinge embodiment, the hinge is located between two parts of the system  100  where the system  100  actually folds in half. In this case, the cover is actually the other half of the system  100  and not merely a protective layer or surface. In this case, when the device is opened and fully extended, the hinge automatically powers up the system  100 . On the other hand, when the hinge is rotated such that the device is fully retracted and folded, the hinge automatically causes the system  100  to enter the power conservation mode. 
         [0066]    The preferred embodiment of the present invention, a method and system for automatically powering-up and automatically powering-down a computer system based on the position and/or rotation of an associated stylus, is thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.
A method and system for changing the power state of a portable electronic device is disclosed. A portable electronic device may be powered up or powered down responsive to a user interaction with the portable electronic device. The user interaction may be an insertion of a stylus or other user interface object into a housing of the portable electronic device. Alternatively, the user interaction may be a removal of a stylus or other user interface object from the housing of the portable electronic device. The user interaction may be a rotation of a cover of the portable electronic device.