Abstract:
The inkjet stylus includes a nozzle for depositing ink onto a writing surface. The ink is drawn from an ink cartridge, which may contain a plurality of ink containers, each holding a different color ink. A switch mechanism is used to select different combinations of ink to produce different colors. A microcontroller controls the switch mechanism so as to select the combination of inks that will produce the desired color, and also controls how the ink is deposited on the writing surface using the nozzle. A battery powers the electronic devices in the inkjet stylus.

Description:
RELATED APPLICATION DATA 
     This invention is related to commonly assigned U.S. patent application Ser. No. 09/816,556, titled “Coordinated Knob and Display For Navigation of Hierarchical and Range Selectors,” filed Mar. 23, 2001, incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This invention pertains to a writing device, and more particularly to a writing device incorporating multiple colors. 
     BACKGROUND OF THE INVENTION 
     The arts of writing and drawing are ancient ones. Cave paintings are some extraordinarily early examples of drawing. And written language goes back at least as far as Egyptian culture. 
     But there have always been limits to what can be done with writing and drawing. First and foremost is the limitation of “one pen=one color and pen size.” Even today, graphic artists have tremendous numbers of pens, each dedicated to a single combination of color and nib size. Further, manufacturers generally limit the color choices available to artists. When the graphic artist wants a different color or to use a different nib, the graphic artist must change pens, and find a pen with the best match for the desired color. 
     Painters typically work with only a few brushes of different sizes, and mix their own colors. But even with only a few brushes, changing the size of the brush requires changing brushes. Further, reusing brushes requires cleaning them with chemicals. And mixing colors on a palette is difficult work, requiring a high degree of skill to know what colors to mix and in what proportions. 
     The present invention addresses this and other problems associated with the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an inkjet stylus according to an embodiment of the invention. 
     FIG. 2 shows the procedure used by the inkjet stylus of FIG. 1 to write on a piece of paper. 
     FIG. 3 shows the procedure used by the inkjet stylus of FIG. 1 to apply a new style. 
     FIG. 4 shows the procedure used by the inkjet stylus of FIG. 1 to draw a picture. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows an inkjet stylus according to an embodiment of the invention. In FIG. 1, inkjet stylus  105  includes nozzle  110 . Nozzle  110  is responsible for applying ink to the surface of the paper. The ink is drawn from ink cartridge  115 . Ink cartridge  115  includes ink containers, such as ink containers  120 - 1  and  120 - 2 , which store the ink fed to nozzle  110 . In one embodiment, ink cartridge  115  includes 4 ink containers, storing inks in the colors cyan, yellow, magenta, and black, which can be mixed to produce any desired color. However, a person skilled in the art will recognize that ink cartridge  115  may include more or fewer ink containers, and may include different colors of ink. Ink cartridge  115  may be designed so that the ink containers are individually replaceable, or may only be replaced as a unit with the ink cartridge. Ink cartridge  115  also includes valves, such as valve  125 . Valve  125  delivers ink from the ink container within ink cartridge  115  to nozzle  110 . 
     Switch mechanism  130  is responsible for selecting the colors of ink to be delivered to the nozzle. Switch mechanism may specify that any combination of colors in ink cartridge  115  be delivered to nozzle  110  by the valves. This also includes the possibility of a single color (i.e., ink is drawn from only one ink container). The inks drawn from the containers are then mixed in the correct proportion to produce the desired color of ink that is applied to the writing surface by nozzle  110 . 
     Inkjet stylus  105  also includes motion sensor  135 . Motion sensor  135  is responsible for sensing the movement of inkjet stylus  105 . When inkjet stylus  105  is lifted from the writing surface, motion sensor  135  senses this and stops the flow of ink through nozzle  110 . In various embodiments, motion sensor  135  may include pressure sensors to detect when nozzle  110  is no longer pressed to the writing surface, an optical surface to detect when inkjet stylus  105  is moved by changes in light, and accelerometers to determine when inkjet stylus  105  has moved relative to a starting point on the writing surface. 
     In a second embodiment, inkjet stylus  105  not only writes in any desired color, but also writes using any desired line style. For example, inkjet stylus  105  may write using a variety of line widths. Alternatively, inkjet stylus  105  may write using a line pattern, so that when the user draws a line, portions of the line are inked, and other portions of the line are left blank. In this embodiment, motion sensor  135  senses the movement of inkjet stylus  105  to determine when nozzle  110  should apply ink to the writing surface and when nozzle  110  should not apply ink. 
     Microcontroller  140  controls the application of ink to the writing surface via nozzle  110  (depending on the line style being used). Microcontroller  140  receives input from motion sensor  135  and instructs nozzle  110  when to apply ink and how much ink to apply. Microcontroller  140  is also responsible for instructing the ink containers within ink cartridge  115  to dispense ink via the valves. In this manner, microcontroller  140  is responsible for selecting the colors of ink to be mixed for application by nozzle  110  to the writing surface. 
     Because inkjet stylus  105  requires power, battery  150  provides the necessary power to the electronics within inkjet stylus  105 . This includes microcontroller  140 , switch mechanism  130 , and nozzle  110 , among other electronic components. A person skilled in the art will recognize that other power sources than a battery may also be used. For example, other “untethered” power sources may also be used, such as fuel cells, and “tethered” power sources, such as an alternating current adapter and cable, may also be used. 
     In an alternative embodiment, inkjet stylus  105  includes color sensor  145 . Color sensor  145  samples a color to which inkjet stylus  105  is pointed. Microcontroller  140  then determines the appropriate combination of colors of ink to mix to produce the sampled color. (The combination of colors needed to produce the sampled color may be stored in a memory, not shown in FIG. 1.) Color sensor  145  may include a calibrated light source to sample the color source. 
     In an alternative embodiment, inkjet stylus  105  may include a selection device, which may be used to select a desired ink color or line style. In FIG. 1, the selection device includes knob  155  and display  160 . Knob  155  is used to navigate a menu. Twisting knob  155  allows a user to view the different choices within the menu: for example, to select a desired ink color or line style. Pushing or pulling knob  155  allows the user to select or reject a current choice in the menu. A person skilled in the art will recognize that either pushing or pulling knob  155  may be used to select or reject a selection, but it is more intuitive to push knob  155  in the direction of selection device  1  OS to select a menu choice. 
     As the user navigates the menu using knob  155  (both by twisting knob  155  and by pushing or pulling knob  155 ), display  160  is updated to reflect the current choice. Thus, as the user twists knob  155 , display  160  scrolls up/down to reflect the change in the selection, “rotating” the selection in display  160  to correspond with the direction knob  155  is rotated. Then, when the user selects or rejects a selection, display  160  scrolls left/right to reflect the selection or rejection of a choice in the menu. 
     The menu navigated by the user is stored in a memory within inkjet stylus  105  (not shown in FIG.  1 ). If the menu initially includes ink colors and line styles, as more colors and line styles are introduced to inkjet stylus  105 , the menu may grow. For example, in the embodiment shown in FIG. 1, inkjet stylus  105  may include plug  165  to which a second device may be connected. The menu update may then be downloaded from the second device (which may be a computer or any other device with which inkjet stylus  105  may interoperate). Alternatively, in a second embodiment, the mechanism for updating the display may include a wireless receiver (not shown in FIG.  1 ), which may be used to receive updates to the menu. 
     The menu may have only a single level (with one or more selections), or it may have multiple levels. If the menu has multiple levels, then some selections within the menu will cascade to a lower level menu. Accepting these selections will open the lower level menus. Conversely, if the user is at a lower level menu and rejects a selection, the user will be brought to a higher level menu. 
     FIG. 2 shows the procedure used by the inkjet stylus of FIG. 1 to write on a piece of paper. At block  205 , the user selects a drawing style (for example, a desired ink color and/or line style). At block  210 , ink is drawn from the ink cartridge. Ink may be drawn from more than one ink container within the ink cartridge, so that when the colors of ink drawn are mixed, they produce the desired ink color. At block  215 , the ink is delivered to the nozzle. At block  220 , the movement of the stylus is monitored to make sure that ink is only applied to the writing surface and not randomly squirted into the air. Motion and pressure sensors within the stylus determine whether the stylus is moving and in contact with the writing surface. This also insured that when the stylus is not in motion (for example, if the user stops moving the stylus because he is in thought), ink does not continue to saturate the writing surface even if pressure is applied. Finally, at block  225 , the ink is applied to the writing surface according to the drawing style, so that the correct color ink, line style, and other parameters are used. 
     FIG. 3 shows the procedure used by the inkjet stylus of FIG. 1 to apply a new style. In FIG. 3, there are two ways a new style may be applied. At block  305 , a new drawing style is input through a port in the inkjet stylus. As described with reference to FIG. 1, this input port may be a port on the stylus to which a second device can be plugged, or the input port may be a wireless receiver designed to receive the drawing style via a wireless transmission (utilizing, for example, radio-frequency (RF) transmission, infrared transmission, Bluetooth, or any other wireless communication protocol). Alternatively, at block  310 , the color style can be scanned by the stylus itself using a color sensor. Either way, at block  315 , the new style may be applied. 
     Another use for the embodiments of the invention is to reproduce an input picture. FIG. 4 shows the procedure used by the inkjet stylus of FIG. 1 to draw a picture. At block  405  the inkjet stylus receives the input pattern (i.e., the picture). As discussed above, the pattern may be input using an input port or may be received wirelessly. At block  410 , the motion of the inkjet stylus is tracked relative to a starting point. At block  415 , the current point of the inkjet stylus is compared to the starting point. The corresponding point in the input pattern is determined, and at block  420  the color of that point in the input pattern is determined. At block  425 , ink is drawn that, when mixed, produces the color of the point in the input pattern. Finally, at block  425 , the ink is applied to the writing surface. Then, as the user moves the stylus around on the writing surface, eventually the pattern will be completely reproduced. 
     Having illustrated and described the principles of our invention in an embodiment thereof, it should be readily apparent to those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. We claim all modifications coming within the spirit and scope of the accompanying claims.