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United States Patent 3,832,071
Chaney August 27, 1974

DISPENSER FOR ERROR CORRECTING FLUIDS

Abstract

A pigmented volatile fluid dispenser having a chamber for holding the fluid which has a valve dispensing end and a vent for equalizing the pressure between the chamber interior and the dispenser environment.


Inventors: Chaney; Preston E. (Dallas, TX)
Appl. No.: 05/343,370
Filed: March 21, 1973


Current U.S. Class: 401/260 ; 401/258; 401/261; 401/264
Current International Class: B43K 5/00 (20060101); B43L 19/00 (20060101); B43K 5/18 (20060101); B43k 001/06 ()
Field of Search: 401/258-260,273,135,217

References Cited

U.S. Patent Documents
748383 December 1903 Langill
948832 February 1910 Trotzky
1457875 June 1923 Coates
1937660 December 1933 Luker
2435123 January 1948 Biro
3535049 October 1970 Bok
Primary Examiner: Charles; Lawrence
Attorney, Agent or Firm: Olsen; James D.

Claims



What is claimed is:

1. Apparatus for dispensing a volatile pigmented fluid comprising: an elongated housing; a fluid dispensing opening at the lower end of the housing; a valve adjacent the fluid dispensing opening which includes a valve seat formed by the interior wall of the opening, a valve stem having an annular sealing surface urged against the valve seat by a spring member, and spring retaining means; a capillary vent positioned at the upper end of the housing; and a partition interposed between the valve and the capillary vent and including a passage therethrough sized to prevent counter-current flow of air and volatile pigmented fluid.

2. The apparatus of claim 1 including a cap member having a rod-like portion extending into the interior of the housing and wherein the upper end of the housing has a solid portion with a cylindrical bore therethrough and wherein the capillary vent is formed by a capillary size space between the rod-like portion of the cap member and the cylindrical bore.

3. The apparatus of claim 2 wherein the cap member rod portion has an upper end having a diameter approximately equal to the diameter of the cylindrical bore so as to provide a slidable friction fit between the cylindrical bore and the rod portion and wherein the section of the rod portion below the rod portion upper end and within the cylindrical bore is generally cylindrical and has a flat side.

4. The apparatus of claim 3 wherein the cap member has an upper and lower position relative to the housing and including means for limiting upward movement of the cap member relative to the housing.

5. The apparatus of claim 4 wherein the cap member rod portion has a lower end sized to fit into and plug the partition passage when the cap member is in the lower position.

6. Apparatus for dispensing a fluid which includes a pigment and volatile solvent comprising: a housing capable of holding the fluid having an opening in the lower end of the housing; a stylus extending through the opening in the lower end of the housing; a valve located adjacent the opening in the lower end of the housing; a valve located adjacent the opening in the lower end of the housing capable of preventing flow of the fluid to the opening in the housing and the stylus; a capillary vent having a cross-sectional area which is small compared to the mean free path of molecules of vapor of the volatile solvent; a partition interposed between the opening and the lower end of the housing and the capillary vent which forms in the housing a liquid chamber and a vapor chamber which are interconnected by an orifice in the partition sized to prevent simultaneous flow of liquid and gas; and movable means for selectively plugging the partition orifice and the capillary vent.

7. The apparatus of claim 6 wherein the selective plugging means includes a vertically movable cap member having an upper end positioned atop the housing and having a diameter greater than the diameter of the housing, and a rod portion extending below the cap member having a lower end capable of plugging the partition orifice.

8. The apparatus of claim 7 wherein the cap member rod portion has an upper end capable of plugging the capillary vent and including means for limiting vertical movement of the cap member.

9. Apparatus for dispensing a volatile pigmented fluid comprising: a housing capable of containing the volatile pigmented fluid and having an opening in the lower end of the housing and having an enclosed cylindrical conduit in its upper end; a stylus projecting through the opening in the lower end of the housing; valve means located adjacent the opening in the housing and arranged to control fluid flow through the opening; capillary vent means including a movable rod positioned in the housing conduit and sized to provide a friction fit with the conduit and having a reduced diameter portion for providing a capillary space between the conduit and the rod; a partition interposed between the vent means and the opening in the housing having an aperture therethrough sized to prevent countercurrent flow of air and the volatile pigmented fluid; and means for controlling the flow of fluids through the capillary vent means comprising a fully diametered upper end of the movable rod.

10. The apparatus of claim 9 including a cap means attached to the upper end of the rod and located atop the housing; including a stop member which limits vertical movement of the cap means and rod and permits the fully diametered upper end of the rod to clear the housing conduit, and wherein the rod has a lower end sized to plug the partition aperture, and wherein the lower rod end plugs the partition aperture when the upper rod end is positioned in the housing conduit.
Description



BACKGROUND OF THE INVENTION

This invention relates to pigmented volatile fluid dispensers and more specifically to pens for dispensing error correcting fluids.

There currently are various methods of correcting errors in typing, writing, drawing, etc. The oldest error correcting method which is still often used is erasure. The main problem with this method of correction is the appearance of the work once corrected. The surface being corrected is often marred by erasure, especially when ink from pens or typewriters is used. This often occurs when all but very high quality paper is utilized. Most typing paper has a smooth exterior finish which can be broken when abrasives are applied. Once the finish is broken, a fibrous substrate is exposed causing a noticeable mar in the paper surface. In addition, correcting ink and typing errors by erasure can be time consuming. If typewritten work is being corrected it is often done while the paper is in the machine to facilitate accurate retyping. When erasing is done while the paper is in the machine, small bits of the erasure often gain access to the workings of the typewriter. As a result, professional cleaning of the machine is required more often thereby increasing upkeep expenses.

Another often used method of correcting errors in typewritten work is by the use of tapes coated with a white material. The tape is placed against the letter to be corrected and the typewriter key corresponding to the letter being corrected is restruck. When the tape is struck by the typewriter key it forces the white material hard against the letter being corrected. In this manner, the white material is transferred atop the letter being corrected, thereby giving it a white covering. If the letter is not entirely covered by the white material, the process can be repeated. This procedure is usually fairly satisfactory for single letter and single copy typewriter corrections, however, it is very time consuming for larger multi-letter and multi-copy errors. Additionally, in not too infrequent instances, the white covering material subsequently comes off. This obviously results in an unsightly letter or document as well as obfuscating the letter, word or words. Because of this the tapes cannot be used in the typing of permanent records. In addition, its use is limited to typed work.

Another method available for correcting errors is an ink eradicator process. This most often consists of a two fluid system where one fluid is applied to the error followed by application of the other fluid. This system has several disadvantages, the most important of which is the discoloring of the area contacted by the fluid. In addition, because the correction system uses aqueous fluids, the surface becomes saturated with the liquid, requiring a prolonged drying time and causing a swelling of the fibers resulting in an uneven writing surface.

One error correcting method that can be used on both written and typed work makes use of a volatile pigmented fluid to cover the error. This fluid includes a finely divided pigment, a solvent and an adhesive. This type fluid is commercially available in both a brush applicator and a pen dispenser. In using the brush applicator the fluid is painted over the error. In a short time the volatile solvent evaporates leaving the dry white pigment covering the error and bonded to the paper by the adhesive. Once the error is covered the correction can be made on top of the white covering. One advantage of this method is the speed with which multi-letter corrections can be made. The main disadvantage is that the pigment may be of a slightly different color from some typing paper, or other writing surfaces. This difference in coloration is hardly noticeable on single letter corrections but on large corrections it becomes highly noticeable. If, however, the work is duplicated, even large areas of correction are usually not noticeable on the copies.

A pen applicator allows more precise coverage of errors since the pen tip affords a smaller and stiffer surface for contacting the error. It would appear to be advantageous to use a pen applicator for reducing or eliminating the conspicuousness of a correction. Many problems, however, exist with present pen applicators. If the pen has not been recently used, the pigment contained in the correction fluid wil crust over the applicator tip. This requires careful and time consuming cleaning of the tip before each use. Often some dried out bits of pigment will remain on the pen tip causing lumps of pigment to be dispensed while errors are being corrected. In these situations, the corrected error is highly noticeable. In addition, when the pen has been held for a short time heat is transmitted by the hand to the air in the interior of the dispenser causing the air therein to expand and forcibly eject correction fluid from the pen. This prevents precise use of the pen and often makes such a mess that the entire work has to be redone. Because of the shortcomings of the present error correcting fluid dispenser, it is an object of the present invention to provide an improved pen for dispensing correction fluids.

SUMMARY OF THE INVENTION

With this and other objects in view, the present invention contemplates pigmented volatile dispenser which is made up of a housing having a valved opening at one end of the housing and having means for venting the housing .

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional elevational view of a commercially available error correcting fluid dispenser.

FIG. 2 is a cross sectional elevational view of applicant's error correcting fluid dispenser.

FIG. 3 is a sectional view of the dispenser of FIG. 2 taken along lines 3--3.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an error correcting fluid dispenser presently commercially available. This dispenser has a hollow cylindrical housing 10 made of a hard plastic material. Force fitted into the lower end of the housing 10 is a stylus housing 16 which has an upper end adapted to be friction-fit against the internal diameter of the housing 10. The lower end of the stylus housing is tapered to a reduced diameter and has an opening 36 at its lower end. Extending through the opening 36 is solid plastic stylus 14 which is generally cone shaped having a tip 24 which is shown in contact with a surface 26 on which there is an error to be corrected.

Formed in the upper end of the stylus 14 is a cylindrical recess 22 for receiving a spring 20. This spring may be made of a plastic, metal or other spring like material. The spring 20 is held in place by an annular retainer 18 which is friction fit against the interior wall of the stylus housing 16.

The interior wall of the lower end of the stylus housing 16 acts as a valve seat 30. Adjacent the valve seat 30, the stylus 14 has an exterior surface portion which acts as a valve stem 32. The retainer 18, spring 20 and stylus 14 are sized and positioned so that the valve formed by valve seat 30 and valve stem 32 is normally in a closed position.

Located in the interior of housings 10 and 16 is error correcting fluid 12. This fluid 12 includes a finely divided pigment, a volatile solvent and an adhesive. The housing 10 is not completely filled with the fluid 12 and has a substantial amount of air 28 located in the upper end of the housing 10.

In use, the valve located at the lower end of stylus housing 16 is opened by forcing the stylus tip 24 against a surface such as 26. The pressure applied to the tip 24 is transmitted to the spring 20 which compresses in response to the pressure. This compression acts to open the valve and release the error correcting fluid 12 through the opening 36. The fluid 12 adheres to the outer surface of the stylus 14 until it runs off the tip 24 onto the surface 26.

Once the fluid 12 is on the surface 26 and exposed to the atmosphere, the volatile solvent quickly evaporates leaving the dried pigment. This pigment covers the error, allowing a correction to be made on top of the pigment.

Several serious problems exist in this dispensing mechanism. When the dispenser has been unused for a period of time, a crust of pigment forms around the opening 36. This requires scraping the dried pigment from the stylus 14 adjacent the opening 36 by inclining the dispenser and rubbing that area of the stylus 14 against a surface to remove the dried pigment. Once the stylus has been scraped the act of forcing the valve open and closed several times usually acts to sufficiently free the valve to permit fluid 12 to exit through the opening 36.

The reasons for the pigment drying in the opening 36 relate to the makeup of the fluid 12 and the way the valve is configured. The valve has a large area of contact between the valve stem 32 and the valve seat 30. The fluid 12 coating the valve stem and valve seat has finely divided solid pigment therein which prevents complete closure of the valve. As the volatile solvent vaporizes adjacent the opening 36, it leaves behind a capillary system formed by the solid pigment remaining. This capillary system extracts the solvent from the fluid 12 remaining between the valve seat 30 and valve stem 32. By this process the entire valve area is clogged with the solid pigment which obstructs movement of the valve and fluid 12 therethrough.

Once the problem of dried pigment clogging the opening 36 has been rectified by scraping and valve manipulation, another problem arises. When the housing 10 becomes heated by the users hand the heat is transmitted to the air 28 contained therein. The air expands in response to the heat and increases the pressure on the fluid 12 to force it at a high rate through the opening 36. Much more fluid than is desired is thus suddenly disgorged onto the surface 26 being corrected. This often causes the entire work to be unfit for use requiring redoing the entire piece.

The air expansion problem is due to the air 28 being confined in a fixed volumetric area. So long as this air 28 is completely confined, large pressure changes occur because it is not free to expand and contract with temperature variations. In order to obviate this problem it is necessary to equalize the pressure in the housing interior. Pressure equalization can be accomplished by venting the housing to the environment or by use of an elastic bladder which is also vented to the environment.

A vent consisting of an aperture through the wall 10 would act to equalize the pressure in the housing. The fluid 12 however, would quickly act to plug the vent with dried solids, because the vent becomes wetted with the correction fluid and is exposed to the atmosphere. Because of this situation frequent cleaning of the vent would be required and excessive loss of solvent would result. The use of an elastic bladder would be quite expensive because common elastomers are not made of a material compatible with the volatile solvents normally used in the correction fluid.

Although uneven flow of the fluid from the dispenser is primarily caused by heating and cooling of the air 28 it is also difficult to control the flow rate due to the nature of the valve. Slight vertical movements of the stylus 14 rapidly change the size of the annular opening 36 which acts to regulate the amount of fluid being dispensed. With only a short movement of the stylus 14 the valve goes from a closed position to a full open position. Because of the difficulty of controlling the amount the valve is opened, the amount of fluid being dispensed cannot be easily regulated.

Because of these problems, the present pen-like dispensers are seldom used and instead, the brush applicators are used despite imprecise application of the fluid, rapid loss of solvent and inadvertent coating of the hands, desk, and typewriter.

Referring next to FIG. 2 is seen applicant's error correcting fluid dispenser which does not have the draw backs described in relation to the dispenser of FIG. 1.

The dispenser includes a hollow cylindrical housing 10 for holding the pigmented volatile error correcting fluid 12. The housing 10 is made up of a stylus housing 62 and a vent housing 76. These housings are held together by friction fit between the lower end of the vent housing 76 which has a reduced diameter portion 74 which fits within the interior wall of the upper portion 72 of the stylus housing 62.

The stylus housing 62 has a tapered lower end with a small opening 36 having the end 24 of a stylus 14 extending therethrough. The stylus 14 is held in place by a spring 20 acting against the stylus 14 and the retainer 18. The spring can be made of a metal, plastic or similar spring-like material. While the retainer is preferably made of plastic and is friction fit against the interior wall of the stylus housing 12 it may also be made of other rigid materials. The stylus 14 has a cylindrical spring recess 22 formed at its upper end. The lower end of the spring 20 fits down within the cylindrical spring recess 22 and is held there by the annular retainer 18.

The stylus 14 has a first cylindrical portion 50 having a valve stem section 46 at its lower end. Below the valve stem section 46 is a second cylindrical portion 38 which has the stylus point 24 at its lower end. The stylus housing 62 has an interior wall portion 52 which is spaced a short distance from the first cylindrical portion 50 of the stylus 14. The annular space 84 between the wall portion 52 and the cylindrical portion 50 is sized so as to meter the error correcting fluid 12.

The interior wall of the stylus housing 62 adjacent the valve stem section 46 is formed into a valve seat 44 by reducing the interior diameter of the stylus housing 62 to provide an annular shoulder. Thus, the valve stem 46 and valve seat 44 provides a valve which is ordinarily held closed by the urging of spring 20. Upon compression of the spring 20 the valve is open. The spring 20 is compressed by applying pressure against the stylus point 24.

Below the valve, the interior wall of the stylus housing forms a cylindrical channel having an interior wall portion 42. This wall portion 42 together with the second cylindrical portion 38 are spaced apart to leave an annular space 48.

Located in the upper end of the stylus 62 is divider 64 having a small opening 40 in its center. This divider 64 is formed to provide a smooth downwardly sloping upper surface. The divider isolates the fluid 12 in the lower portion of the dispenser and creates a chamber 85 between the divider 64 and the lower end of the vent housing 76.

The vent housing 76 is substantially solid but has a cylindrical channel 82 extending its length which has a channel surface 70. Located atop the vent housing 76 is cap 56. This cap 56 has a larger diameter than the housing 10.

Extending downward from the underside of the cap 56 is a rod 58. The rod 58 extends through the cylindrical channel 82 in the vent housing 86. The rod 58 has a cylindrical upper end 60 of short length. Below this cylindrical end 60, the rod 58 is generally cylindrical except for having a flat side 78. This flat side 78 reduces the cross section area of the rod 58 below the cylindrical end 60.

The relationship between the rod 58 and the cylindrical channel 82 can best be seen by referring to FIG. 3 which is a cross section taken along line 3--3 of FIG. 2. There the vent housing 76 is shown as having a cylindrical channel 82 in its center including interior wall 70. Occupying most of the channel 82 is rod 58 having the flat side 78. Because of this flat side 82 there is left a space 80 which is sized to act as a capillary vent. This capillary space 80 extends the length of the cylindrical channel 82 when the cylindrical upper end 60 of the rod 58 is removed from the channel 82. There is thus created a capillary channel 80 having a length several times greater than its diameter.

Referring again to FIG. 2, the rod 58 has a lower end 68 of reduced diameter. This lower rod end 68 is shown extending into the opening 40 of divider 64. Lower rod end 68 is sized to slidably plug the opening 40. Positioned above the reduced diameter lower rod end 68, and below the channel 82 formed in the vent housing 76, is stop member 54. This stop member 54 has a substantially larger diameter than the channel 82. This stop member 54 has a cylindrical bore therethrough and is friction fit onto the rod 58. Because of the cylindrical bore through the stop member 54 and the flat side 78 of the rod 58 there is left an opening 34 between the stop member 54 and the rod 58.

In the operation of the dispenser of FIG. 2, when errors are to be corrected, the cap 56 is moved upward to clear the cylindrical upper end portion 60 of the rod 58 from the cylindrical channel 82. This upward movement of the cap 56 also removes the lower end 68 of the rod 58 from the opening 40 in the divider 64. Excessive upward movement of the cap 56 is prevented by impingement of the stop member 54 against the lower end of the vent housing 76. When this cap 56 has been moved upward, air is able to communicate between the dispenser's environment and the interior of the dispenser. This acts to vent the interior of the dispenser in that air can flow beneath the cap 56, down the capillary channel 80, through the opening 34 which is between the stop member 54 and the rod 58, and finally through the opening 40 in the divider 64.

In order to apply the error correcting fluid 12 the stylus point 24 is pressed against the paper atop the error. The pressure is transmitted through the stylus 24 to compress the spring 20. The upward movement of the stylus 14 lifts the valve stem 32 from valve seat 30. The error correcting fluid 12 is then able to flow through the annular space 84 located between stylus cylindrical portion 50 and interior wall portion 52 of stylus housing 62. Fluid 12 then passes through the valve area and through the annular space 48 whereupon it flows down the lower cylindrical portion of stylus 38 to the stylus point 24. In this manner the pigmented volatile error correcting fluid 12 is applied to the error. Once the error has been covered with the volatile pigmented fluid 12 the dispenser is lifted from the surface allowing the volatile solvent to evaporate to leave the dry pigment. When the pigment covered area has dried it can be typed or written on.

Applicant's dispenser provides major advantages over currently available dispensers. The vent system provides several advantages, one of which is relief from temperature cycling. As previously mentioned, change in internal pressure resulting from heating or cooling of air trapped inside the dispenser is the principal cause of erratic flow in present correction fluid dispensers. For example, in the dispenser illustrated in FIG. 1, a 5.degree.F reduction in inside air temperature will create a vacuum sufficient to prevent any fluid flow when the stylus valve is open. On the other hand, a 5.degree.F rise in temperature will approximately triple the normal rate of flow. With normal fluids a simple venting system would solve the temperature cycling problem, however, the very properties required of a satisfactory correction fluid presents serious problems in devising a practical venting system.

Correction fluids must contain a high proportion of pigment in order to cover an error. The suspending agent must be a highly volatile solvent in order that the correction will dry rapidly. In addition, the fluid must contain an adhesive capable of bonding the pigment to the paper. A simple vent such as a small hole in the upper portion of the barrel can be used, however, several problems arise. First, the vent hole can be become wetted with the fluid unless great care is exercised in keeping the dispenser in the vertical position at all times. When the dispenser is positioned to allow wetting of the vent, evaporation of solvent from a drop of fluid in the vent hole will leave dry pigment which quickly plugs the opening and renders the vent inoperative. Even if it were possible to avoid plugging of the simple vent hole, the problem of solvent loss to the atmosphere would cause rapid thickening of the fluid remaining in the dispenser making the fluid too thick to flow properly.

Applicant's venting system is constructed to prevent plugging of the vent passage by dried solids and also limits solvent loss such that the fluid does not become excessively viscous during the normal working life of the dispenser. The solvent loss problem is effectively prevented by the use of the capillary channel 80. The essential requirement of this capillary channel 80 is in that its length be several times greater than its other dimensions and that its cross sectional dimensions be small compared to the mean free path of the solvent vapor and air molecules contained therein. Generally speaking, the length of the channel 80 is usually at least five times greater than its cross sectional dimension. This capillary channel 80 might be made in many forms other than that shown in FIG. 2.

The capillary channel 80 has been found to be extremely effective in controlling solvent loss by evaporation. This is best understood by considering what takes place at an interface between solvent vapor and air within the capillary. The gaseous molecules are in a state of thermal agitation which in a spherical container would result in rapid mixing of the two gases to the point of a uniform composition throughout the container. However, in a capillary channel 80, as above described, collisions with the capillary walls severely restrict the travel of gaseous molecules such that the rate of mixing of air and solvent vapor molecules at the interface is greatly reduced. With the additional specification that the capillary channel be several times longer than its greatest cross-sectional dimension, it will be found that the rate of mixing between vapor in the dispenser and the outside air is so slow as to be negligable. Hence, the capillary channel 80 provides an effective barrier against solvent evaporation while simultaneously providing an open channel for pressure equalization between the dispenser interior and the atmosphere.

In fact, the capillary channel is so effective in controlling evaporative loss of solvent that this device alone would provide suitable venting means for an error correction fluid dispenser provided that there is some means for preventing flooding of the capillary channel 80 with the correction fluid. Such flooding could result in plugging of the capillary channel 80. One means to prevent flooding of the capillary channel 80 is to limit the quantity of the correction fluid in the dispenser to an amount that will not reach the exposed end of the capillary channel 80 in any position that the dispenser might be placed. The capillary channel 80 can be constructed of a material such as TEFLON which is not readily wetted by error correction fluid 12.

The preferred means for prevention of flooding of the capillary is shown in FIG. 2. Divider 64 and the cavity between divider 64 and the lower surface of the vent housing 76 serve to isolate fluid 12 from contact with the capillary channel 80. Opening 40 in divider 64 is small enough to prevent simultaneous countercurrent flow of liquid and gas. Hence, even though the dispenser be inverted so as to flood opening 40 with correction fluid 12, only a tiny droplet of fluid will enter chamber 85 before flow stops entirely. The volume voided by the flow of fluid through opening 40 can only be filled by flow of vapor in the opposite direction. Since opening 40 does not permit simultaneous countercurrent flow, all flow comes to a halt.

A venting system consists of only divider 64 with opening 40, isolation chamber 58 and capillary channel 80 above the isolation chamber 85 and capillary channel 80 above the isolation chamber will overcome many of the drawbacks of present dispensers. The presence of divider 64 with opening 40 provides better isolation between fluid 12 and the internal end of the capillary channel 80. Hence, more fluid can be stored in the dispenser without danger of flooding the capillary channel 80 in normal use. In addition, the use of the cap 56 having a larger diameter than the remainder of the dispenser prevents the liquid from reaching the capillary channel 80 by elevating the cap end when the dispenser is laid down. However, a dispenser of this design is subject to damage if stored for considerable lengths of time in the inverted position. Such damage is particularly likely if while inverted the dispenser is also subjected to large temperature and/or pressure fluctuations such as might be encountered during air shipments. Under these conditions, opening 40 and divider 64 will be continuously flooded with correction fluid. Furthermore, fluctuations in external pressure or fluid vapor temperature will cause the pressure in the fluid chamber to be alternately greater or less than the pressure in chamber 85. While the small diameter of opening 40 will prevent simultaneous countercurrent flow of gas and fluid, it does not prevent alternate flow. Hence, fluid will be transferred into chamber 85 by these pressure or temperature fluctuations and if in sufficient quantity will flood the capillary channel 80 and render the venting system inoperative.

This problem is overcome by utilization of the lower rod end 68 to plug the opening 40 in the divider 64. During transportation or storage, cap 56 is depressed to its lowermost position which forces lower rod end 68 into opening 40 of divider 64 and thus completely isolates the fluid chamber from isolation chamber 85. Simultaneously the cylindrical portion 60 of rod 58 is forced into the upper end of cylindrical channel 82 and thus completely eliminates loss of vapor during storage or transportation.

If the cap 56 is in its closed position when the dispenser is not being used, it may be stored indefinitely with no apparent deterioration due to evaporation, and when opened, the venting system reliably provides even flow of the correction fluid by equalizing pressure between the dispenser interior and the external environment.

Referring once again to the operation of the dispenser described in FIG. 2, once the upward pressure on stylus 14 is relieved by lifting the stylus tip 24 from the surface on which the error is contained, the spring 20 is able to expand and force the valve stem 46 against the valve seat 44. If no further immediate use of the dispenser is needed, the vent system is also closed by moving the cap 56 downward against the top of the vent housing 76. The present commercially available dispenser develops a severe pigment encrustment problem when not in use for an appreciable period of time due to the length of sealing surface in the stylus valve. Because of the finely divided solid pigment contained in the correction fluid the valve is prevented from closing completely. These finely divided pigment particles thus create an extremely fine capillary system of great length. The volatile solvent is drawn into this pigment capillary system in the same manner as kerosene is drawn into a kerosene lamp wick. Applicant's dispenser overcomes this problem by locating a short valve seat near the stylus opening 36. This small valve closing surface appreciably reduces any capillary network. It has been found that only a slight solids build-up occurs which crumbles and falls away upon pressing the stylus against the paper or other surfaces.

In addition to the improved valve, applicant's dispenser has an annular metering area 84 which provides uniform fluid flow in contrast to the prior art dispensers. When the valve stem 46 moves from the valve seat 44, the annular area 84 permits a consistent limited amount of correction fluid 12 to pass to the stylus tip end 24.

Thus, the primary problems of the present error correcting fluid dispensers have been overcome by applicant's dispenser described in FIGS. 2 and 3. The capillary channel venting system prevents rapid solvent loss and problems due to temperature cycling. In addition, the plugging system afforded by the cap 56 and the related rod 58 allows for lengthy storage times and all dispenser positions without thickening of the fluid due to solvent loss or plugging of the vent. The improved stylus design incorporating the short valve and annular metering feature effectively prevents substantial encrustment of the stylus area by dry pigment. This greatly facilitates quick use after extensive storage time.

In the foregoing description of applicant's invention reference has been made only to dispensing error correcting fluids. It is apparent however, that applicant's dispenser can be used for other fluids such as spotting paints or lacquers which combine pigments with a volatile solvent.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

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