Abstract:
This invention includes a stylus that employs a translucent material for conducting light to convey information from a portable electronic device to a user. In one preferred embodiment, the stylus provides a thermometer style fuel gauge. Inserting the stylus into a special stylus holder actuates the fuel gauge. A thermometer like fuel gauge reading then appears in the body of the stylus. Other embodiments include changing color, focal point of a lens and light intensity to convey information. The stylus may be used to convey any type of information, including receipt of e-mail by the portable electronic device.

Description:
BACKGROUND  
         [0001]    1. Technical Field  
           [0002]    This invention relates generally to portable computers with touch-sensitive screens and rechargeable batteries, and more particularly to a stylus assembly associated with such portable computers.  
           [0003]    2. Background Art  
           [0004]    Personal Digital Assistants (PDAs) are all the rage. It is nearly impossible to go to a business meeting and not see at least one person whip out a handheld, shirt-pocket sized computer and start tapping away at the screen. US Robotics introduced these devices in the mid-1990s. Today, Palm, Inc. is one of the most prolific suppliers of these devices, which are colloquially called “palm organizers”. Other manufacturers of these devices include Sony and Handspring.  
           [0005]    The typical method of using a PDA involves a touch sensitive screen and a pen-shaped object known as a “stylus”. Referring now to FIG. 1, illustrated therein is a PDA  101  and a stylus  100 . To enter data into the PDA  101 , the user takes the stylus  100  and “writes”, as if with a pen on paper, on the touch sensitive screen  102 . The screen interprets the stylus strokes as alphanumeric characters and stores them in the computer&#39;s memory. Such a system is described in U.S. Pat. No. 5,231,281 to Duwaer.  
           [0006]    Some PDAs use primary batteries, like AA sized alkaline batteries. Other PDAs use rechargeable batteries, like lithium-ion cells. The PDAs with rechargeable batteries include a cradle for charging. To charge the battery, the user places the PDA in the cradle. Electrical contacts in the cradle then meet with electrical contacts in the battery to charge the battery. Such a cradle is shown in FIG. 2.  
           [0007]    Most PDAs include some form of fuel gauge. The fuel gauge tells the user how much battery capacity remains. These fuel gauges generally take the form of a picture of a battery on the screen, with a shaded region to indicate the remaining battery capacity. Referring now to FG.  6 , fuel gauge indicator  600  is approximately three-fourths shaded, indicating about 75% battery capacity remaining.  
           [0008]    A problem exists with this method of fuel gauge indication. This type of fuel gauge is only displayed on the screen when the PDA is turned on. Thus, if the PDA is charging in the cradle, the user does not know how much battery capacity remains without turning the PDA on. Powering the device adds a load to the charger that reduces charging efficiency.  
           [0009]    Additionally, the fuel gauge typically is only displayed on the main menu screen. Consequently, if a user is working in his calendar, he must stop working and toggle over to the main screen to see the fuel gauge. Such interruptions in work waste time.  
           [0010]    There is thus a need for an improved fuel gauging device. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 illustrates a prior art portable computer and stylus.  
         [0012]    [0012]FIG. 2 illustrates a prior art cradle for a portable computer.  
         [0013]    [0013]FIG. 3 illustrates a stylus in accordance with the invention.  
         [0014]    [0014]FIG. 4 illustrates a cross sectional view of a stylus in accordance with the invention.  
         [0015]    [0015]FIG. 5 illustrates a cradle having a stylus receptacle in accordance with the invention.  
         [0016]    [0016]FIG. 6 illustrates a prior art fuel gauge. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    A preferred embodiment of the invention is now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” Roughly stated, this invention provides a stylus assembly that provides a way to determine the remaining battery capacity in a handheld computer. Referring now to FIG. 3, illustrated therein is one preferred embodiment of a stylus  300  in accordance with the invention. The stylus  300  includes a writing end  301  having a tip  302  for making contact with the touch screen of a portable computer. The stylus has a body  303  through which the fuel gauging information is displayed. The stylus  300  includes a back end  304 , which may include a finger grip  305  to assist in removing the stylus  300  from its carrying holder in a portable computer.  
         [0018]    In one preferred embodiment, the body  303  of the stylus  300  includes light carrying optical fibers  306 - 308 . Each fiber  306 - 308  is of a differing length and is connected to a corresponding window  309 - 311  on the writing end  301  of the stylus  300 . For example, fiber  306  is coupled to window  309 , fiber  307  is coupled to window  310 , and so on.  
         [0019]    When no light is being projected into the windows  309 - 311 , the stylus body appears as a single, solid color. Illuminating a particular window, however, causes the corresponding fiber to illuminate. When the fiber length is correlated to battery capacity, a thermometer-like readout is available to the user. For example, in this illustrative embodiment, fiber  306  may correspond to full capacity, while fiber  307  corresponds to half capacity, and so on.  
         [0020]    While any number of fibers may be included, one preferred embodiment includes four fibers. A cross section of such a stylus is shown in FIG. 4. The writing end  301  of the stylus is shown in cross section. The finger grip  305  may also be seen in this cross sectional view. The writing end  301  of the stylus has been divided into quadrants. A window is included in each quadrant. Window  309  corresponds to fiber  306  of FIG. 3 and represents full capacity. Window  310  corresponds to fiber  307  of FIG. 3 and represents half capacity. Window  311  corresponds to fiber  308  of FIG. 3 and represents one-quarter capacity. Window  401  corresponds to a fiber not shown in FIG. 3 and represents 75% capacity.  
         [0021]    A special stylus receptacle provides the light needed to illuminate one of the windows, and thus one of the fibers. Such a stylus holder may be included in a cradle or in the portable computer itself. Referring now to FIG. 5, illustrated therein is a cradle  500  having such a stylus receptacle  501 . For illustrative purposes, the exemplary stylus  300  from FIGS. 3 and 4 has been inserted into the stylus receptacle  501 . The interior of the stylus receptacle  501  has been sectioned into quadrants that correspond to the stylus quadrants shown in FIG. 4. Each quadrant of the stylus receptacle  501  includes a light source, preferably a focused light emitting diode (LED). The stylus receptacle  501  is equipped with a push-button switch such that when the stylus  300  is inserted into the stylus holder  501  and depressed, the appropriate light is actuated.  
         [0022]    Battery capacity information may be obtained from either the host device itself or from charging circuitry disposed in the cradle  500 . For example, the portable computer may deliver battery capacity information through electrical contacts  502  in the cradle  500 . This information is then conveyed to the user via the stylus  300 . By way of example, if the battery is 75% full, the portable computer delivers this information to the cradle  500 . The cradle  500  keeps the real-time capacity stored in a memory device. When the user inserts the stylus  300  into the stylus holder  501 , the light corresponding to 75% is actuated by way of the push button switch. The appropriate window is illuminated, thereby causing the fiber that runs three-quarters of the way up the stylus is illuminated. The user sees a thermometer-like reading of about three quarters, and knows that the battery is 75% full.  
         [0023]    Note that while a cradle is nice, the stylus holder may alternately be coupled to the computer itself. The stylus holder would operate in exactly the same manner, without the need of the cradle. The advantages of this embodiment include the fact that a cradle is no longer required to use the special stylus. Additionally, when user is working in a specific application, like the date book for example, the user simply checks the capacity with the stylus and holder without having to exit the date book program. The stylus receptacle may also be coupled to a rechargeable battery.  
         [0024]    While the multiple light source-sectioned stylus and holder method works well, there are other preferred embodiments that work equally well. One such embodiment uses a shutter. Rather than having separate light sources for illumination of the windows, a single light source is provided with a rotatable shutter having an aperture equal in area to that of one of the windows. When the stylus holder is actuated, the shutter rotates to align the aperture with the appropriate window, thereby actuating the appropriate fiber. This embodiment reduces the number and alignment of light sources, as a general light source may be used. The shutter is easily tooled from injection-molded plastic and does the work of precision alignment of the light source.  
         [0025]    An alternate embodiment involves using a single light-conducting stylus with either a single or no fibers. (In the no fiber embodiment, the plastic stylus body operates as a large, single fiber.) In this particular embodiment, the entire stylus is illuminated when the stylus is placed in the stylus holder. Battery capacity is communicated to the user preferably in one of two ways: color or intensity.  
         [0026]    In the embodiment employing color, multiple light sources are again used. For example, a red and green LED may be used. When the battery is less than one-third full, the red LED may actuate upon depression of the push button switch. If the battery is between one third and two thirds full, both the red and green LEDs may light, thereby giving a yellow light. If the battery is more than two thirds full, the green LED may light. In this fashion, the user determines the battery capacity by the color of the stylus when inserted into the stylus holder.  
         [0027]    In the embodiment employing light intensity, a single light source is used. The intensity of light is changed to reflect battery capacity. For example, if a LED is used as the light source, the luminous intensity may be altered by altering the current flowing in the LED. Thus, depending upon battery capacity, a plurality of current limiting resistors may be coupled to the LED. A multiplexing circuit then switches in the appropriate resistor for the particular battery capacity. A weakly lit stylus may indicate low battery status, while a brightly lit stylus may indicate full capacity.  
         [0028]    Another alternative embodiment involves using a single light source with a lens to change the focal point of light within the stylus. In this embodiment, there is no line or bar of light projected. Instead, a moving star of light appears in the stylus. When the star is at the bottom of the stylus the battery is empty, whereas when the star is at the top, the battery is full. This is achieved by way of a lens and a changing focal point. The focal point of the light in the stylus forms the light star. By changing the focal length, the star moves up the stylus proportionally with battery capacity.  
         [0029]    While the preferred embodiments of the invention have been illustrated and described, it is clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the following claims. For example, illustrative embodiments of this invention have centered on battery capacity. The invention could be employed for other types of information as well. By way of example, for portable computers with wireless capabilities, the stylus may illuminate when a new e-mail has arrived. Additionally, alarm information, like calendar events and to do list items may cause actuation.  
         [0030]    Additionally, the stylus is not limited to portable computers. It is applicable to any electronic device employing a stylus, including cellular phones and pagers.