Abstract:
A writing instrument includes an elongated body housing a spool valve and a writing tip secured to a distal end of the elongated body. Two or more fluid reservoirs in selective fluid communication with the writing tip. Axial movement of the spool valve relative to the elongated body of the writing instrument alternately establishes fluid flow paths between the fluid reservoirs and the writing tip.

Description:
BACKGROUND 
     The present invention relates to writing instruments, and in particular to writing instruments utilizing colored inks, pigments, and/or dyes in a suspended fluidic state. 
     When dealing with writing fluids such as inks, paints, dyes, and/or pigments, subtractive color theory applies, as opposed to additive color theory where a light source passes through colored filters. Subtractive color theory is that of mixing inks, paints, dyes and/or other natural pigments to make colors that absorb and reflect particular wavelengths of light. For example, for printing, cyan, magenta, and yellow are primary colors. Black may be added for various reasons in a four color process, most importantly because cyan, magenta, and yellow do not produce “pure” black but more of a dark gray. 
     Subtractive color theory is based on what light is absorbed. The amount of any color showing will depend on the amount of each of the three primary colors is in a color mixture. Cyan is the opposite of red. Magenta is the opposite of green. Yellow is the opposite of blue. The amount of blue in the final color mixture is directly related to the amount of yellow ink that is in the color mixture. The same is the case for other primary colors. For example, orange is a common color that is generally equal amounts of red and yellow. Adding more yellow will create a lighter orange. Adding more red will create a red orange. Green color is a combination of cyan and yellow. 
     The subtractive color theory starts with the presence of all colors of light, usually as white light reflected from a white surface, such as paper. Dyes or inks may be used to subtract some of the reflected light. Understanding subtractive color theory requires an understanding of how colors of light are subtracted. If yellow dye or ink is applied on a white sheet of paper, one may think that color is added to the paper, but the color is already there; the white paper reflects all colors of light approximately equally. The yellow ink, however, reflects only red and green light and absorbs blue light, thereby subtracting it from the white light. Any color of ink, dye or paint subtracts its complementary color of light. Cyan ink on white paper absorbs red light, and allows green and blue to be reflected. Magenta ink subtracts green light, and allows red and blue to reflect. Yellow ink absorbs blue light, allowing red and green to reflect. Cyan, magenta and yellow are the subtractive primary colors, and combined in pairs, they produce the colors red, green and blue. When all three primary colors are subtractively combined, they subtract all colors of light, leaving black, typically a dark gray is the practical result. 
     When two primary colors are overlaid, they each subtract one color, allowing only the third color to be reflected. For example, if magenta and yellow ink are mixed or applied on white paper, the magenta ink absorbs green light. The yellow ink subtracts blue light. Neither of them absorbs red light, so red light is reflected by white paper, and a viewer sees the color red. In a sense, the colors experienced in a subtractive color mixture are created in the same way they&#39;re created with an additive mixture. A combination of red and green light (where the red and green colors each contain light from one-third of the spectrum) will always produce a yellow-colored light (containing light from two-thirds of the spectrum). It doesn&#39;t matter whether one starts with white light and subtracts one-third of the spectrum, or starts with no light (black) and adds two thirds of the spectrum. Similarly, green and blue light always combine to produce cyan-colored light, and red and blue light always combine to produce magenta-colored light. Complementary colors work in similar ways for both additive and subtractive mixtures. In additive mixtures for example, yellow and blue light combine to complete the spectrum, producing white light. In subtractive mixtures, however, yellow and blue produce black (yellow and cyan produce green). Yellow ink subtracts one-third of the spectral light, blue ink subtracts the other two-thirds of the light, resulting in a black color. As previously noted, black is difficult to achieve in the subtractive process, and for that reason a four color process may be desired in some situations in order to achieve a true black color. 
     In summary, the subtractive color system involves colorants and reflected light. Subtractive color starts with an object (often a substrate such as paper or canvas) that reflects light and uses colorants (such as inks, pigments or dyes) to subtract portions of the white light illuminating an object to produce other colors. If an object reflects all the white light back to the viewer, it appears white. If an object absorbs (subtracts) all the light illuminating it, no light is reflected back to the viewer and it appears black. 
     SUMMARY 
     A writing instrument may include an elongated body housing a spool valve, fluid reservoirs, and a writing tip secured to the elongated body in selective fluid communication with the fluid reservoirs. The spool valve may be axially moveable relative to the elongated body of the writing instrument. 
     In one instance an object of writing instrument described herein is to provide a low cost variable color writing instrument capable of full spectrum color. 
     In another instance an object of the writing instrument described herein is to maximize the words, characters and the like written with the writing instrument before refilling the writing fluid in the fluid reservoirs, and whereby, for example, a user may write in excess of 100 times more words, characters and the like with a given amount of writing fluid, as compared to existing writing instruments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features, advantages and objects of the present invention are attained can be understood in detail, a more particular description of the invention briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. 
       It is noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a perspective view of a writing instrument; 
         FIG. 2  is an exploded perspective view of the writing instrument shown in  FIG. 1 ; 
         FIGS. 3A-3C  are perspective views of the spool valve of the writing instrument shown in  FIG. 1 ; 
         FIG. 4  is a section view of the elongated body of the writing instrument shown in  FIG. 1 ; 
         FIG. 5  is a side view of the spool valve of the writing instrument shown in  FIG. 1  with hidden lines shown in phantom; 
         FIG. 6  is a top view of the writing instrument shown in  FIG. 1  with hidden lines shown in phantom; 
         FIGS. 7A-7D  are perspective views of the writing instrument shown in  FIG. 1  depicting various axial positions of the spool valve relative to the elongated body of the writing instrument; 
         FIG. 8  is perspective view of a second embodiment of a writing instrument; 
         FIG. 9  is a side view of spool valve of the writing instrument shown in  FIG. 8  depicting a flexible wall of a fluid reservoir pressed against a rigid member mounted on the spool valve; 
         FIG. 10  is a perspective view of a third embodiment of a writing instrument; 
         FIG. 11  is a side view of the writing instrument shown in  FIG. 10  with hidden lines shown in phantom; 
         FIG. 12  is a perspective of the elongated body of the writing instrument shown in  FIG. 10  with hidden lines shown in phantom; 
         FIG. 13  is a top plan view of the body of the writing instrument shown in  FIG. 12 ; 
         FIG. 14  is a perspective view of the spool valve of the writing instrument shown in  FIG. 9  with hidden lines shown in phantom; and 
         FIG. 15  is a top plan view of the spool valve shown in  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     As used herein the term “fluid” means inks, paints, dyes, pigments, water, alcohol, mixing solutions, surfactants and other flowable fluids suitable for marking on a substrate material, such as paper and the like. 
     Referring first to  FIG. 1 , a writing instrument is generally identified by the reference numeral  100 . For purposes of illustration, but not by way of limitation, the writing instrument  100  is depicted in the drawings as a “fountain pen” and will hereinafter be referred to as a “pen.” 
     The pen  100  may include a pen barrel  112 , a spool valve  114 , a cap  116  and a writing tip or nib  118 . The spool valve  114 , shown in the exploded view of  FIG. 2 , may include an elongated stem  120 , a head  122  and a threaded distal end  126 . The head  122  may include a griping portion  124 , for example a thumb grip. The stem  120  extends downwardly from a lower transverse wall  128  of the head  122 . The stem  120  may be integrally formed with the head  122  or fixedly secured to the head  122  by means known in the art. A lower portion of the stem  120  may include lands  130  and circumferential grooves  132  axially spaced along the lower portion of the stem  120 . O-rings  135  may be concentrically and axially constrained in the grooves  132 . The stem  120  terminates at a lower distal end defined by a transverse wall  133 . 
     The head  122  of the spool valve  114  may include two or more fluid reservoirs. The pen  100  shown in  FIGS. 3A-3C  depicts three reservoirs  134 ,  136  and  138 , for illustrative purposes only and not by way of limitation. The reservoirs  134 ,  136 ,  138  are separated by walls  140  and extend from the distal end  126  of the spool valve  114  downward into the head  122 , terminating at a transverse wall  142  depicted in phantom in  FIG. 5 . 
     The reservoirs  134 ,  136 ,  138  may be sealed by the cap  116  threadedly secured on the distal end  126  of the spool valve  114 . A flexible washer  141  and a rigid washer  142  in the cap  116  ensure an air and liquid tight seal for the reservoirs  134 ,  136 ,  138 . 
     Referring now to  FIG. 4 , the barrel  112  of the pen  100  may, for illustrative purposes, but not by limitation, include an elongated substantially cylindrical body  150 . The upper end portion of the body  150  includes a box end or receptacle  152  sized and configured to receive the head  122  of the spool valve  114 . A borehole  154  concentric with the vertical axis of the body  150  extends axially downward from the receptacle  152  to a transverse bottom wall  156 . The upper end of the borehole  154  opens to the interior of the receptacle  152 . The borehole  154  is sized and configured to receive the stem  120  of the spool valve  114 . Upon assembly of the barrel  112  with the spool valve  114 , the o-rings  135  seal against the inner surface of the borehole  154  isolating the lands  130  from one another. 
     The pen barrel  112  may include a conduit  158  establishing a fluid pathway between the borehole  154  and a mixing chamber  160  proximate the lower distal end of the barrel  112 . An axial passage  119  may extend from the mixing chamber  160  to the distal end  121  of the pen barrel  112 . The passage  119  is configured to receive the connector end  123  of the nib  118 . The nib  118  may be screwed or press fit into the passage  119  thereby securing the nib  118  to the lower distal end of the pen barrel  112 . The upper end of the passage  119  is open to the mixing chamber  160 , thereby establishing fluid communication between the mixing chamber  160  and the nib  118 . 
     Referring now to  FIG. 5 , the spool valve  114  may include one or more conduits for establishing fluid communication between the reservoirs  134 ,  136 ,  138  and the nib  118 . In  FIG. 5 , conduits  162 ,  164  and  166  are shown offset from the central vertical axis of the stem  120  and extend substantially parallel to the central axis of the stem  120 . The conduits  162 ,  164 ,  166  terminate at radially and outwardly directed openings  172 ,  174 ,  176  in the lands  130 . Clearance between the lands  130  and the borehole  154  is sufficient for fluid to flow therebetween. However, it is understood that other configurations, such as a concentric groove, may be provided about the lands  130  to allow circumferential fluid flow (ink or solvent and the like) about the lands  130 . 
     The pen  100  may be assembled by inserting the stem  120  into the borehole  154  of the barrel  112 . The head  122  may include a helical groove  180  in the outer surface thereof sized to receive a boss  182  projecting inwardly proximate the open distal end of the receptacle  152 . The boss  182  is constrained to move along the helical groove  180  upon rotation of the spool valve  114  relative to the barrel  112 . Rotation moves the spool valve  114  axially relative to the barrel  112 . The thumb grip  124  provides a convenient surface for grasping and rotating the spool valve  114  clock-wise or counter clock-wise to advance or retract the spool valve  114  from the pen barrel  112 . For the configuration of the pen  100  illustrated in  FIGS. 1-7 , clock-wise rotation moves the spool valve  114  axially downward relative the barrel  112 . Counter clock-wise rotation moves the spool valve  114  axially upward relative the barrel  112 . It should be noted that the barrel  112  may likewise be rotated by holding the spool valve  114  and rotating the barrel  112  to move it axially relative to the spool valve  114 . 
     Referring still to  FIG. 5 , the spool valve  114  may include a vent duct  184  having a lower distal opening  186 . The vent duct  184  may be concentric with the central vertical axis of the spool valve  114 . The vent duct  184  may extend axially through the spool valve  114  from the opening  186  at the lower distal end of the stem  120  and vent to the atmosphere through radially outwardly directed air vents  188  in the spool valve head  122 , shown in  FIG. 6 . The vent duct  184  generally functions as a relief valve to release air that may be compressed in the barrel borehole  154  as the stem  120  advances downward in the borehole  154 . Venting air out of the borehole  154  may avoid air pressure fluctuations that may interfere with fluid flow from the reservoirs  134 ,  136   138  into the conduit  158 . 
     Fluid may be distributed to the pen nib  118  upon alignment of the upper open end  159  of the conduit  158  with openings  172 ,  174 ,  176  in the stem  120 . As previously noted, rotation of the spool valve  114  moves the stem  120  axially relative to the barrel borehole  124 .  FIGS. 7A-7D  illustrate the location of the stem  120  relative to the upper open end  159  of the conduit  158  for distributing fluid from the reservoirs  134 ,  136 ,  138  to the pen nib  118 . 
       FIG. 7A  depicts the pen  100  in the “off” or non-writing mode. In this mode, the spool valve  114  is depicted as being retracted from the pen barrel  112  to a position so that the lowermost land  130  blocks the opening  159  of the conduit  158 . The lowermost land  130  is not in fluid communication with any reservoir and therefore no fluid is distributed to the pen nib  118 . 
       FIGS. 7B-7D  depict the pen stem  120  positioned so that the opening  159  of the conduit  158  aligns with the openings  176 ,  174 ,  172  in the lands  130 , thereby establishing fluid communication between a respective reservoir  134 ,  136 ,  138  and the pen nib  118 . A user may actuate the spool valve  114 , as desired to distribute a writing fluid from the fluid reservoirs  134 ,  136 ,  134  to the mixing chamber  160  of the pen barrel  112 . The user may change the color, shade and hue of the writing fluid applied to the writing surface in an infinite combination of colors and duration of fluids distributed to the mixing chamber  160  from the fluid reservoirs  134 ,  136 ,  138 . 
     The writing instrument, as noted above, depicted in the drawings is a fountain type pen for illustrative purposes only. It is understood that the writing instrument described herein may include, but is not limited to, ball point pens with viscous ink (considered paste), pens with generally decreasing ink viscosity ranging from tempura pens, gel pens, roller ball pens, brush tip pens, fountain pens, stylus pens, and/or felt tip pens, of both water or alcohol base and the like. 
     The pen  100  may be suitable for a wide range of uses such as a simple novelty item to being able to continuously and smoothly cause a transition of colors while creating a drawing, sketch and the like, and where no two sketches or drawings are identical, even with identical pen motions, because of the somewhat turbulent flow and the complex nature of the physics of a flowing fluid. Viscosity alone is a complex and somewhat chaotic factor to consider, as well as the dynamics of the spool valve or other valves, such as disk valves or pinch valves. 
     The subtractive color system, described in greater detail hereinabove, applies to the pen  100 . The full color spectrum may be possible with the ink colors magenta, yellow, and cyan. Generally, pen  100  may be considered a “color shifting pen” utilizing three reservoirs (or three cartridge) of compatible or mixable inks. Color shifting pens may be controlled with the spool valve described hereinabove. The pen  100  may be used for various purposes, such as, notarizing documents or dealing with legal matters, or even writing a diary. The chronological order of the written words, characters and the like may be determined by the ink color. If insertions occur out of sequence, the color of such insertions provides an indication as to the general time period, based upon the ink color, that such insertions were made. In this respect, the use of color may greatly assist in the prevention of fraud and forgeries. Note that it would be very difficult to re-blend the identical ink color. Forensic document examination may also be greatly facilitated. The reader will note that the chronological order is not actually a function of time, but rather a function of the number of words, characters and the like the pen has written. Furthermore, in addition to ink, fluorescent dyes which fluoresce under ultraviolet light may be introduced into one or more of the reservoirs, for example, in order to introduce unique graduations which would only be visible under UV light. 
     Continuing again with ink mixtures, the ink colors throughout a sketch, drawing or writing are a smooth transition of many colors, hues, and shades. A user may create the sketch or drawing while controlling and anticipating the colors being mixed and/or blended and delivered to the writing tip. For example, while shades of yellow are being delivered to the writing tip, the sun or yellow objects may be sketched, and as the user introduces green blended ink, then plants and/or green objects may be sketched. Furthermore, during color mixing, and particularly when utilizing fountain pens, it should be noted that the quantity of ink colors available in the market is high, and the user may elect to deviate from the three subtractive primary colors discussed above and select non-primary colors which, for example, may result in mixtures of pastel colors. Alternatively, scarlet, purple and/or green ink may be included in at least one of the reservoirs to emphasize a particular mixable range of colors. Also, for steady delivery of a mixed color or shade, positioning the spool valve to a predetermined intermediate position between two fluid reservoirs, both in the “on” mode in some portion (throttling), steady state mixing action may occur while writing. 
     All colors are possible with the three reservoir configuration of the pen  100  where the primary subtractive colors are provided. With regard to secondary colors, if the primary subtractive colors of yellow, cyan, and magenta are provided, then a secondary color such as red, green or blue may be mixed and delivered to the pen mixing chamber, and once such a color is in the mixing chamber, a new primary color may be introduced resulting in colors such as violet, rose, orange, chartreuse green, spring green, and azure to be mixed within the pen mixing chamber and thereafter delivered to the writing tip. Further variations when combining tertiary and secondary colors, or tertiary and tertiary colors, or any combination of the above colors are also possible, thus enabling a remarkably wide variation of the number of colors, shades and hues which may be gradually mixed within the pen mixing chamber during the act of writing. 
     Directing attention now to  FIGS. 8 and 9 , a second embodiment of a spool valve pen is generally identified by the reference numeral  200 . As evidenced by the use of common reference numerals, the pen  200  is similar to the pen  100  described above with the exception that the pen  200  may include a dual reservoir system where one or the other of the two reservoirs is always in the “on” or open mode. That is, a fluid reservoir is always in fluid communication with the pen nib  118 . The pen  200  does not include an “off” mode. 
     In  FIG. 8 , the water reservoir  285  of the pen  200  is set to the “on” mode and the ink reservoir  275  is in the “off” mode. A spool valve  214  is received in the pen barrel  220  in the same manner as the spool valve  114  is received in the pen  100 . The ink reservoir  275  is relatively small compared to the relatively large water reservoir  285 . The ink reservoir  275  and water reservoir  285  are mounted on the spool valve  214  on opposite sides of a rigid stanchion wall  280 . Both reservoirs  275 ,  285  may be fabricated of flexible material that facilitates quick and convenient refilling of the reservoirs  275 ,  285 . The reservoirs  275 ,  285  may be refilled by pressing the flexible side of either reservoir  275 ,  285  against the rigid stanchion wall  280 , as illustrated in  FIG. 9 , much like squeezing the bulb of an eye dropper, and thereby expelling any air in the reservoir. The nib  118  may then be submerged into water or ink and the like. Release of the pressure on the side of the reservoirs draws the fluid into the reservoirs. Prior to refilling a reservoir of the pen  200 , a small amount of diluted writing mixture may be retained in the pen mixing chamber  160  to facilitate efficient refilling of the reservoir. The pen  200  may include additional ink reservoirs as desired, all generally being flexible reservoirs that lend themselves to the vacuum filling method described above. 
     The pen  200  is typically used with the water reservoir  285  in the “on” position operating as a “dilution pen” or in the “dilution” mode. The pen  200  may be operated with alcohol based inks, in which case the smaller reservoir  275  may contain alcohol ink, and the larger reservoir  285  may contain alcohol and/or a mixing solution. Additional reservoirs may be included as desired, for example, water, alcohol, and a mixing solution in separate reservoirs. Cartridges or converters known in the art may be substituted for the flexible reservoirs if desired. The selection of proper O-rings for water or alcohol use is understood, and silicon O-rings may generally suffice. An unillustrated cap or sleeve may be provided to cover the reservoirs  275 ,  285 . Rotation of the spool valve  214  counter clockwise relative to the pen barrel  220 , engages the boss  221  with helical groove  238 , thereby causing the spool valve  214  to be raised and the ink reservoir  275  moved to the “on” position. 
     With regard to ink dilution, a user may change a color shade, or economize ink consumption. The darkness of 100× diluted ink may in many cases be as dark as lead pencil on paper, and easily reproducible with computer copiers and scanners and the like. When economizing the use of ink, and having once filled the ink reservoir  275  of the pen  200  with standard dark (nearly saturated) fountain pen ink, the user may write a hundred times more words, characters and the like with the dilution pen  200  than with use of ink alone. Ink cost savings would be notable, and the pen  200  would also be more environmentally friendly than any other pen available on the market currently. 
     By some estimates, when writing with a prior art medium point fountain pen with 1 cc (one cc=one ml) typical ink capacity, for example, a user may expect to write 5-15 pages of sketches or words per one cc of ink alone. With one cc of standard dark fountain pen ink in the ink reservoir  275  of the pen  200 , and considering a  100   x  factor of dilution, the user may expect to write 500 to 1500 pages of sketches or written words with the dilution pen  200 , which is a remarkable extension of writing. An entire book may be written without refilling the ink reservoir  275 . It may also be noted that an additional advantage to diluting ink is that diluted ink dries significantly faster than a nearly saturated ink. 
     For further refinement of the use of a fountain pen, a user may introduce surfactants and lubricants, in powder or liquid form, to one or more pen reservoirs, at any time while using the pen. Generally, when economizing ink by providing a pen with a water reservoir, use of water soluble inks is recommended. Fountain pen inks are typically an aqueous solution and generally 92+% water, adding water is inherently compatible. If notable diminished flow or lubrication properties are evident, a drop of clear dish detergent in the water reservoir may solve flow problems and a drop of pure vegetable glycerin may solve lubrication problems. Kodak PhotoFlo may also be used as a surfactant to aid ink/water flow. TritonX-100 may be another suitable surfactant. The Triton pure chemical is concentrated and should be diluted to create a working solution, where a “working solution” of Triton X-100 may be prepared at a 1:200 dilution, and a drop of the working solution is sufficient for one fountain pen water reservoir. Use of too much surfactant may inhibit the ink/water flow. In a fountain pen, the writing fluid should optimally spread along the underside of the nib and fill in the combs in the collector. Too much surfactant and the ink solution may drip out of the nib. Use of distilled water may result in optimum results. 
     For use of tempera inks, where the ink viscosity is relatively thick (like honey), the spool valve may be proportionally greater in size, and have larger ink passageways and/or orifices and/or clearances. When using alcohol based inks, note that one of the pen reservoirs may be filled only with alcohol, or filled only with a “mixing solution”, and the other reservoirs may be filled with alcohol based inks. Ethanol (Ethyl alcohol) is a preferred alcohol ink base. 
     Directing attention now to  FIGS. 10-15 , a third embodiment of a spool pen generally identified by the reference numeral  300  is shown. The pen  300  is similar to the pens  100  and  200  described above with the exception that the pen  300  includes reservoirs  331 ,  332 ,  333 , shown in  FIG. 13 , and reservoir passageways  361 ,  362 ,  363 , shown in  FIG. 12 , integrally formed with the pen barrel  320 . The pen  300  may include seven O-rings  325  on the stem  365 , best shown in  FIGS. 11 and 13 . O-rings  325  are concentrically constrained within recesses  370  of the stem  365 . The lower distal ends of the passageways  361 ,  362 ,  363  are redirected radially inward at openings  352 ,  353 ,  354 , respectively. An axial center passageway  377  concentric with the longitudinal axis of the stem  365  provides a conduit for the distribution of fluid, such as ink or solvent and the like, to the fluid mixing chamber  360 , shown in phantom lines in the drawings, upon alignment of the stem inlet openings  380  with the passageways  361 ,  362 ,  363 . Boss  321  is constrained to move along helical groove  338  thereby causing the pen barrel  320  to move axially relative to the spool valve  330  as one rotates relative to the other. Reservoirs  331 ,  332 ,  333  are isolated from each other by walls  340 . An agitator such as a small metal ball may be included within each reservoir to maintain ink suspension. The blind end of the stem  365  may be vented in a similar manner as described hereinabove with reference to pens  100 ,  200 . 
     The nib  318  may be screwed or press fit into a borehole  319  at the lower distal end of the spool valve  330 . The upper end of the borehole  319  is open to the mixing chamber  360 , shown in phantom lines in the drawings, thereby establishing fluid communication between the mixing chamber  360  and the nib  318 . 
     While various embodiments of the invention have been shown and described herein, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims which follow.