Abstract:
One aspect of the invention involves the output of a radio frequency (RF) identification tag by a writing instrument to indicate ink color or another characteristic associated with a line style parameter of the writing instrument. The RF identification tag is a wireless signal that uniquely identifies the line style parameters, such as physical-ink or virtual-ink color, produced when using the writing instrument. A writing tablet receives the RF identification tag and signals a computing device, responsible for displaying graphical representations made on the writing tablet, to display a portion of the graphical representation formed by that writing instrument with the characteristics of the line style parameters specified by the RF identification tag.

Description:
FIELD 
   The invention generally relates to the field of writing devices. More specifically, one embodiment of the invention relates to a device and method for communicating a unique identifier, being representative of line style parameters associated with a writing instrument, to a writing tablet. 
   GENERAL BACKGROUND 
   Over the past decade, both parents and institutions are relying more heavily on educational toys as supplement learning tools. One popular education toy is a writing tablet that is communicatively coupled to a computer. Normally, a stylus or other non-ink producing writing instrument accompanies the tablet. As one end of the stylus comes into contact with a writing surface of the tablet, its location is registered by a sensing mechanism situated within the tablet. In response to the user gliding the stylus across the writing surface of the tablet, outlining a desired graphical representation (e.g., a handwritten alphanumeric character, an image, etc.), the computer generates a corresponding graphical representation for display on its monitor screen. 
   One problem with conventional writing tablets is that the user has no ability to discern what color is currently associated with the stylus. The current color associated with the stylus is merely ascertained by the user when the graphical representation being rendered on the tablet is displayed on the computer monitor. This may slightly impede the learning of colors by children and unnecessarily causes drawing errors by the user who may not be aware of the selected color or particular line thickness or patterns produced by the stylus. 
   Another problem with conventional writing tablets is that regular ink-filled writing instruments cannot be used with the tablet. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the invention will become apparent from the following detailed description of the present invention in which: 
       FIG. 1  is an exemplary embodiment of a writing tablet communicatively coupled to a writing instrument. 
       FIGS. 2A and 2B  are a collective representation of a first embodiment of the writing tablet of  FIG. 1  is shown. 
       FIG. 3  is a first exemplary embodiment of the writing instrument of  FIG. 1 . 
       FIGS. 4A and 4B  are a collective representation of a second exemplary embodiment of the writing instrument of  FIG. 1 . 
       FIGS. 5A and 5B  are a collective representation of a second exemplary embodiments of the writing tablet of  FIG. 1 . 
       FIG. 6  is a third exemplary embodiment of the writing instrument of  FIG. 1 . 
       FIGS. 7A and 7B  is a collective representation of a fourth exemplary embodiment of the writing instrument of  FIG. 1 . 
       FIG. 8  is a fifth exemplary embodiment of the writing instrument of  FIG. 1 . 
       FIG. 9  is an exemplary block diagram of a flowchart featuring the operations of the writing tablet in communication with the writing instrument of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   In general, one embodiment of the invention generally relates to a device and method for communicating line style parameters such as physical or virtual ink color of a writing instrument using a unique identifier. For clarity, the term “writing” and related tenses used herein involve the act of handwriting and/or drawing. Also, certain details are set forth below in order to provide a thorough understanding of the invention, albeit the invention may be practiced through many embodiments other that those illustrated. Well-known circuits and operations are not set forth in detail in order to avoid unnecessarily obscuring the invention. 
   In the following description, certain terminology is used to describe certain features of the invention. For example, a “computing device” includes logic, namely hardware, firmware, software module(s) or any combination thereof that performs a desired function. In one embodiment, the computing device is a computer such as a desktop computer, laptop computer, hand-held (e.g., personal digital assistant), a mainframe, a workstation, a server or any computer architecture. Other examples of computing devices include, but are not limited or restricted to other communication equipment such as an alphanumeric pager, a facsimile machine, a set-top box or a wireless telephone for example. 
   A “physical-ink writing instrument” is any device that dispenses writing solution during use. Examples of writing solution includes ink, dry powder inclusive of chalk, crayon, lead and the like. Examples of a physical-ink writing instrument includes a marker, ink-filled pen, pencil, crayon, etc. A “virtual-ink writing instrument” is any device that, during use, does not dispense writing solution. Examples of a virtual-ink writing instrument includes a stylus. 
   A “software module” is a series of instructions that, when executed, performs a certain function. Examples of a software module include an operating system, an application, an applet, a program or even a routine. One or more software modules may be stored in a machine-readable medium, which includes but is not limited to an electronic circuit, a semiconductor memory device, a read only memory (ROM), a flash memory, a type of erasable programmable ROM (EPROM or EEPROM), a floppy diskette, a compact disk, an optical disk, a hard disk, and the like. 
   In addition, a “link” is generally defined as one or more physical or virtual information-carrying mediums to establish a communication pathway. Types of mediums include electrical wire, electrical or optical cable, air in combination with wireless signaling technology employed at the computing device and/or a writing tablet, and other means of communication. 
   A “graphical representation” includes one or more lines segments (e.g., visible points connected together) that form (i) handwritten alphanumeric characters or symbols or (ii) images featuring any geometrical shaped object or artistic rendering. The alphanumeric characters may be in any case (upper/lower) or style (cursive or printed) and in accordance with any character type (e.g., Roman, Kanji, Arabic, Chinese, etc.). 
   A “line style parameter” indicates indicia associated with line segments produced by a writing instrument. Examples of various types of indicia may include, but are not limited or restricted to physical or virtual ink color, line segment thickness, line segment pattern types (e.g., solid, dashed, dotted, spray or any other graphic object), animation effects (e.g., wiggle, stamps, sparkle, etc.), special effects (e.g., blending of colors, line segment thickness or patterns, animated effects or any combination thereof between two intersecting line segments, masking through removal of color, line segment thickness or patterns, or animated effects within a region of intersecting line segments, color reversal by changing a color within a region of intersecting line segments to a prescribed opposite color, etc.) as well as levels of transparency or erasure. 
   Referring to  FIG. 1 , an exemplary embodiment of a writing tablet  100  communicatively coupled to a writing instrument  110  over a link  120  is shown. For this particular embodiment, the link  120  includes one or more wireless channels. These wireless channels support the transfer of data between the tablet  100  and the writing instrument  110  in a unidirectional or bi-directional fashion as shown. The data transfer may be as radio frequency (RF) signals in accordance with recognized modulation and demodulation techniques. Of course, in the alternative, the wireless communications may be conducted through infrared or other wireless communication protocols as well as physical mediums such as electrical wires or cable where the writing instrument  110  is tethered to the tablet  100 . 
   As shown in  FIGS. 2A and 2B , a collective representation of a first exemplary embodiment of the tablet  100  is shown. The tablet  100  comprises a housing  200  made of a rigid material such as hardened plastic. The housing  200  protects internal logic  210  employed within the housing  200 . One surface  220  of the housing  200  features a writing area  230  being a region made of a semi-opaque material having a translucent or transparent quality (e.g., plastic, glass, etc.) or a liquid crystal display (LCD) screen. In one embodiment, the writing area  230  is sized to accommodate an overlay of standard letter size paper (8.5″×11″), although other sized screens may be implemented as an alternative. 
   In one embodiment, a graphical representation written by the user over the writing area  230  is transferred to a computing device (not shown). The computing device is in communications with the tablet  100  and controls display of the graphical representation on a monitor screen of the computing device (hereinafter referred to as the “device monitor”). Alternatively, the graphical representation may be displayed on the writing area  230  of the tablet  100  itself. 
   As shown in  FIG. 2B , the internal logic  210  includes a wireless receiver  240 . The wireless receiver  240  receives wireless signals from one or more writing instruments in accordance with a unicast or multicast communication scheme. The transmission range for the wireless signals may be adjusted so that the wireless receiver  240  can detect the wireless signals from writing instruments that are in contact with or in close proximity to the writing area  230  (e.g., less than one centimeter from the surface). Normally, this range may be varied by adjusting the level of effective isotropic radiated power (referred to as the “power level”) utilized by the wireless receiver  240 . However, it is contemplated that the power level may be configured to be at a constant level. 
   The wireless receiver  240  is capable of receiving an incoming wireless signal  250  from the writing instrument  110  as shown in  FIG. 1 . The incoming wireless signal  250 , generally referred to as a “RF identification tag” for this embodiment, operates as a unique identifier by identifying line style parameters associated with the writing instrument. 
   For example, the RF identification tag may indicate the color of either the physical-ink or virtual-ink writing instrument currently in use with the tablet  100 . Different RF identification tags are associated with different colors, where each color type corresponds to a unique RF identification tag. The RF identification tag may further indicate, for example, that the line segments produced by the writing instrument during use have a prescribed line thickness and/or pattern. 
   Referring now to  FIG. 3 , a first exemplary embodiment of the writing instrument  110  of  FIG. 1  is shown. For this embodiment, the writing instrument  110  operates as a virtual-ink writing instrument that does not dispense writing solution during use. As the user places the writing instrument  110  in physical contact with the writing area of the tablet and glides the writing instrument  110  over the writing area, the tablet signals the computing device to display a graphical representation as made in the writing area. In the event that the graphical representation is displayed in color, it is important for the writing instrument  110  to identify a selected color represented by the virtual-ink writing instrument (referred to as the “virtual-ink color”) to the tablet. Also, it is important for the writing instrument  110  to identify other indicia represented by line style parameters associated therewith. 
   Herein, for this embodiment, the writing instrument  110  includes a casing  300  made of a rigid material such as hardened plastic. The casing  300  protects a transponder  310  that is placed within an inner cavity  305  formed by the casing  300 . Operating as an active RF signaling device or a passive RF signaling device as shown, the transponder  310  provides an RF identification tag, which is a unique, selected frequency resonating from the transponder  310  that corresponds to the line style parameters associated with the writing instrument  110 . 
   As shown herein, one embodiment for the transponder  310  may be an inductor-capacitor (LC) circuit  320 , perhaps adapted to an antenna  325 . The oscillating frequency of the transponder  320  is formed as the capacitor  330  undergoes charging and discharging operations controlled by the inductor  340 . More specifically, as the capacitor  330  discharges, the inductor  340  charges a plate of the capacitor  330 . As the inductor&#39;s magnetic field collapses, the capacitor  330  has been recharged with an opposite polarity. By associating different oscillation patterns with different line style parameters, the tablet is able to discern the selected color and/or other line style parameter indicia associated with the writing instrument  110 . 
   Referring now to  FIGS. 4A and 4B , a collective representation of a second exemplary embodiment of the writing instrument  110  of  FIG. 1  is shown. For this embodiment, the writing instrument  110  contains a writing solution within a substantially sealed reservoir container and extrudes the writing solution when used. 
   The writing instrument  110  includes a casing  400  generally encapsulating a reservoir container  410 . The reservoir container  410  stores the writing solution  415  and supplies the writing solution  415  to a writing head  420  of the writing instrument  110  during use. The writing head  420  may be a porous felt marker tip, a ball point and the like. 
   As generally shown, a sleeve  430  is adapted for placement over an outer surface  405  of the casing  400 . For instance, in one embodiment, the sleeve  430  includes a cylindrical aperture  435  for placement over a portion of the outer surface  405  of the casing  400 . The sleeve  430  is made of a generally pliable material which allows the inner diameter of the cylindrical aperture  435  to be approximately equivalent to or even slightly less than a diameter (D) formed by the outer surface  405  of the casing  400 . This allows the sleeve  430  to fit snugly on the casing  400 . 
   In another embodiment, the sleeve  430  may be made of a rigid material and features an inner diameter formed by the aperture  435  that is substantially equal to the diameter (D) of the casing  400 . Also, for yet another embodiment, the sleeve  430  may be a piece of material with a fastening mechanism (e.g., VELCRO® fastener) that is wrapped around a writing instrument and fastened thereto. 
   The sleeve  430  is adapted with the transponder  310  as described in  FIG. 3 . An RF Identification tag  250  indicates line style parameters corresponding to the sleeve  430 . For example, if the sleeve  430  represents a blue virtual-ink color and a dashed line pattern, the sleeve  430  may illustrate dashed blue lines. The transponder  310  periodically outputs the RF identification tag  250  so that, when proximate to the writing area of the tablet, the tablet can determine the line style parameters of the writing instrument  110 . For clarity sake, further discussion set forth below is directed to ink color (virtual or physical). However, any indicia provided by a line style parameter (e.g., line pattern, thickness, etc.) may be substituted for and included in combination with ink color. 
   As shown in  FIGS. 5A and 5B , a collective representation of a second exemplary embodiment of the tablet  100  is shown. Similar to  FIGS. 2A and 2B , the tablet  100  comprises a housing  500  that protects internal logic  510  and features a writing area  530  on one surface  520  of the housing  500 . 
   As shown in  FIG. 5B , the internal logic  510  includes a wireless transceiver  540 . The wireless transceiver  540  receives wireless signals from one or more writing instruments within a transmission range configured so that the internal logic  510  can detect the wireless signals from writing instruments that are in contact with or in close proximity to the writing area  530 . 
   For this embodiment, the wireless transceiver  540  comprises an antenna  541  and a processor  542 . Internally maintained within the housing  500 , for this embodiment, the antenna  541  enables wireless signals to be transmitted from and received by the tablet  100 . Alternatively, it is contemplated that the antenna  541  may be adapted to protrude from the housing  500  in order to mitigate any interference caused by the housing  500 . 
   Successive wireless signals may be generated by the processor  542  and periodically transmitted by the tablet  100  at a first approximate frequency. Normally, the periodicity is static in nature; however, it is contemplated that it may be configured to be programmable. Of course, in order to support and detect multiple colors of writing instruments, the tablet  100  may be adapted to periodically transmit multiple wireless signals at different frequencies within a predetermined frequency range. For illustrative sake, the wireless signals are described as types of radio frequency (RF) signals. 
   In one embodiment, the processor  542  generates an outgoing RF signal referred to as a “color inquiry signal”  550 . The color inquiry signal  550  is transmitted over the antenna  541 . In response, the antenna  541  may receive an incoming RF signal  560  from a writing instrument  110  as shown in  FIG. 1 . The incoming RF signal  560 , referred to as a “color reply signal,” is processed by the processor  542  in order to extract information therefrom. For this embodiment, the extracted information includes a RF identification tag transmitted by the writing instrument. As previously described, the “RF identification tag” is data that indicates the virtual-ink or physical-ink color provided by the writing instrument currently in use. Such data is unique for each color. 
   After extracting the RF identification tag by the writing tablet  100 , the color type represented by the RF identification tag is subsequently conveyed to the computing device. This is performed so that the computing device accurately displays on the device monitor the color being used in creating at least a portion of a graphical representation. 
   Referring now to  FIG. 6 , a third exemplary embodiment of the writing instrument  110  of  FIG. 1  is shown. Herein, the writing instrument  110  is a passive RF signaling device that operates as a virtual-ink writing instrument by not dispensing physical-ink during the writing process. Rather, as the user places the writing instrument  110  in physical contact with the writing area of the tablet and glides an end of the writing instrument  110  over the writing area, the tablet signals the computing device to display a graphical representation as made in the writing area. 
   As generally shown, the writing instrument  110  includes a casing  600  made of a rigid material such as hardened plastic. The casing  600  protects a wireless communication circuit  610  that is placed within an inner cavity  605  formed by the casing  600 . The wireless communication circuit  610  includes an antenna  620  and a transponder unit  630  including a signal detector  635  and a color coding circuit  640 . The wireless communication circuit  610  may receive power from one or more power sources placed within the casing  600  such as a battery for example. Of course, where the writing instrument  110  is tethered to the tablet  100  of  FIG. 5A , power may be supplied via that tablet. 
   The antenna  620  is tuned to receive signals at a selected frequency from the tablet. Upon determining that a color inquiry signal  550  at the selected frequency has been received, the signal detector  635  of the transponder unit  630  rectifies the received signal to produce a voltage that activates the color coding circuit  640 . For this embodiment, the color coding circuit  640  produces the color reply signal  560  in response to the color inquiry signal  550 . For one embodiment, the color reply signal  560  is a signal at the selected frequency modulated with a RF identification tag  650  permanently stored within the color coding circuit  640 . The RF identification tag  650  is a unique value representative of the virtual-ink color associated with the writing instrument  110 . 
   Although not shown, an alternative embodiment of the wireless communication circuit  610 , operating as an active RF device, may includes a power source, a transponder and an internal memory. The power source may be one or more removable batteries, which supply power to the transponder and internal memory. The internal memory may be implemented as non-volatile memory to maintain stored data without the application of power from the power source. The stored data would include the RF identification tag. 
   Referring now to  FIGS. 7A and 7B , a collective representation of a fourth exemplary embodiment of the writing instrument  110  of  FIG. 1  is shown. For this embodiment, the writing instrument  110  operates as a physical-ink writing instrument containing a writing solution. 
   The writing instrument  110  includes a casing  700  generally encapsulating a reservoir container  710 . The reservoir container  710  stores the writing solution  715  and supplies the writing solution  715  to a writing head  720  of the writing instrument  110  during use. The writing head  720  may be a porous felt marker tip, a ball point and the like. 
   As generally shown, a sleeve  730  is adapted for placement over an outer surface  705  of the casing  700 . For instance, in one embodiment, the sleeve  730  includes a cylindrical aperture  735  for placement over a portion of the outer surface  705  of the casing  700 . The sleeve  730  is made of a generally pliable material which allows the inner diameter of the cylindrical aperture  735  to be approximately equivalent to or even slightly less than a diameter (D) formed by the outer surface  705  of the casing  700 . This allows the sleeve  730  to fit snugly on the casing  700 . Of course, the sleeve  730  is made of a rigid material and features an inner diameter formed by the aperture  735  that is substantially equal to the diameter (D) of the casing  700  or a single piece of material that can be applied and fastened to any type of writing instrument. 
   The sleeve  730  is adapted with wireless communication unit  610  including the antenna  620  and transponder unit  630  as discussed in  FIG. 6 . The RF identification tag  650  indicates a color that corresponds with the color of the sleeve  730 . The transponder unit  630  periodically outputs the RF identification tag  650  in response to color reply signals from the writing tablet. 
   Referring now to  FIG. 8 , a fifth exemplary embodiment of the writing instrument  110  of  FIG. 1  is shown. Similar to  FIG. 6 , the writing instrument  110  is a virtual-ink writing instrument that does not dispense ink during the writing process. The writing instrument  110  includes a casing  800  made of a rigid material. The casing  800  protects logic  810  placed within an inner cavity  805  formed by the casing  800 . 
   As generally shown, the logic  810  includes an antenna  820  and a plurality of wireless transponder units  830 . Each of the wireless transponder units  830  is adapted to transmit a unique RF identification tag associated with a particular color. The selection of the wireless transponder units  830  is currently associated with the writing instrument  110  is performed by a selector circuit  835  (e.g., switches, etc.) in response to an event. Examples of an event include a user-initiated action such as depression of a depressible button protruding from the casing  800  or rotation a portion of the casing  800  to a rotational position that represents the particular color identifier and the like. After selection of a wireless transponder unit  830 , the particular color coding circuit and corresponding RF identification tag may be used in responding to a color inquiry signal at a frequency recognized by the selected wireless transponder unit. 
   Referring now to  FIG. 9 , an exemplary embodiment of the exchanged communications between the writing tablet and the writing instrument of  FIG. 1  is shown. These operations may be performed, in part, by logic within the tablet such as software modules executed by a processor for example. 
   Upon activation, the tablet periodically transmits a RF signal, referred to as a color inquiry signal, at a selected frequency (blocks  900  and  910 ). Such transmission may occur in a broadcast or multicast capacity for example. The transmission range for a writing instrument to detect the color inquiry signal may be adjusted at manufacturer or adjusted by the user via the computing device. The transmission may be over a portion of the writing surface to assist in identifying the location of the writing instrument. 
   After transmission of the color inquiry signal, the tablet monitors whether it receives a color reply signal within a prescribed time period (block  920 ). If so, logic within the tablet extracts the RF identification tag from the color reply signal and conveys the information to the computing device regarding the ink color associated with the writing instrument (block  930 ). If the color reply signal is not received within a prescribed time period, a color inquiry signal at a different frequency is transmitted in efforts to detect a different color writing instrument in use (block  940 ). This operation is optional (as represented by dashed lines) for those tablets that support multiple colors. The above-described method continues as an iterative process to continuously search for writing instruments being used on the tablet. The periodicity of the transmissions and detection may be fast enough to support multiple writing instruments being used concurrently on the tablet. 
   While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described. For example, it may be possible to implement the invention or some of its features in hardware, firmware, software or a combination thereof.