WO2014083560A1

WO2014083560A1 - Weightless shaking retraction mechanism for a pen

Info

Publication number: WO2014083560A1
Application number: PCT/IL2013/050622
Authority: WO
Inventors: Uri Zaidman; Guy DAGAN
Original assignee: Uri Zaidman; Dagan Guy
Priority date: 2012-11-28
Filing date: 2013-07-22
Publication date: 2014-06-05

Abstract

The present invention describes a mechanism and method for retracting an elongated instrument whereby a brisk movement along the axis of the instrument is used to extract a tip of the instrument and a brisk movement across the axis of the instrument is used to retract the tip of the instrument. In the preferred embodiment, the retraction mechanism is free of designated sliding weight additions, utilizing the weight of the retracted instrument itself to leverage the forces applied by the brisk movements thereby activating the retraction mechanism.

Description

WEIGHTLESS SHAKING RETRACTION MECHANISM FOR A PEN

FIELD AND BACKGROUND OF THE INVENTION

The present invention is related to the field of retraction mechanisms; more specifically, the invention may be applied to the field of retractable instruments having a tip that may be extended or retracted, for example writing instruments.

A retractable tip has many useful applications. Retractable tip pens are popular because by retracting the writing tip while carrying the pen, the tip is shielded from damage and the clothes of the person carrying the pen are protected from ink stains. Retractable fills and knives are also popular for similar reasons.

A retractable tip is preferable to a removable cover because covers often require two-handed manipulation for removal; covers may get lost, and covers may fall off accidentally. Also, pen caps can become a nuisance and even dangerous to small children who like to take things apart and put small parts in their mouths.

For similar reasons, retractable tips may be useful for pocket files and mechanical pencils. Another application for retractable tips is for markers (particularly white board markers), which allow a user to open and close a marker without worry about manipulating, replacing and keeping track of a cap. For example, keeping track of caps can be especially difficult for a lecturer using a few different colored white board markers.

The disadvantage of common retractable tip mechanisms are 1) they are complex (increasing complexity generally implies increases expense and unreliability) 2) many common retractable tip mechanisms require two hands for operation (e.g., for pens that are opened and closed by twisting) and 3) even when a retractable tip mechanism can be opened or closed with one hand, the user must move and regrip his hand in order to open or close the instrument (e.g., for pens that are opened and closed by depressing a button opposite the writing tip, in order to open or close the pen one must move one's grip from the writing grip and grasp the pen opposite the writing tip with fingers only using one's free thumb to open or close the pen).

Furthermore, there is a general desire of many consumers to have a unique pen that is different from the standard. A pen that opens by a non-standard action (e.g., shaking instead of pushing a button) is particularly desirable. Such pens can sell for high prices and particularly if the pen uses a custom refill, selling the refills can be very profitable for the manufacturer.

Therefore, there were developed a few pens which can be opened and closed by simple shaking or inverting. For example Saida '979 (U.S. patent no. 4,176,979) discloses a magnetically closed pen that opens automatically when the pen is held in an attitude wherein the writing tip is slanted downward (the usual writing attitude) and closes automatically when the pen is held with the writing tip upward (the preferred storage attitude). Nevertheless, the pen of Saida '979 has a few significant disadvantages. Firstly, the pen must be stored with the writing tip pointed upward. Such a storage direction may lead to leakage of ink from the back of the ink tube. Such a storage attitude may also lead to drying of the pen point and require waiting or shaking to rewet the tip before writing. Such shaking may be problematic with the mechanism of Saida '979. Furthermore, Saida '979 teaches that extending the writing tip and keeping the writing tip extruded depends on keeping the pen tilted so that gravity pushes the rear end of the ink tube against a projection that prevents the tip from retracting, Thus the pen of Siada '979 may not open or may not remain open properly when held at an improper attitude. Furthermore, the pen of Saida '979 requires that the ink tube be magnetically attractive and cannot be used with a standard plastic tube ball-point refill. Kersten '511 (U.S. patent no. 2,813,511) discloses a ball-point pen that can be opened by shaking, and can be opened by pulling and releasing a spring clip. The pen of Kersten '511 includes at least a few important disadvantages. Firstly, retracting the writing tip requires complex manipulation of the spring clip. Secondly, in the writing configuration (with tip extended) there is no force holding the ink reservoir cover element 40 up against the shoulder 42 of the pen. Therefore, when the writing tip is pushed down against a writing surface there will be an annoying play as the reservoir cover element 40 retracts very slightly until it contacts the shoulder 42. Thirdly, Kersten '511 requires a magnetizable ink reservoir and cannot use a standard plastic pen refill. Furthermore, in order for the writing tip to lock in the extended writing configuration requires sideward pressure from spring clip 48. As spring clip 48 fatigues over time, the pressure will loosen and the pen may fail to lock in the writing configuration.

Hsieh '224 (U.S. patent no. 6,921,224) discloses a pen that can be opened and closed by shaking and that is capable of employing a standard plastic ball-point pen refill. Nevertheless, the pen of Hsieh '224 has significant disadvantages, at least because of the dependence on an elastic claw-shaped rear stopper. In the writing configuration (tip extended) all of the writing force rests on the elastic claw-shaped stopper. Therefore the stopper must be stiff and strong. On the other hand, elastic claw-shaped rear stopper must be supple enough to move easily into and out of the slots in the sliding ring 40 and the tail 13 of the pen. Thus, the flexibility of the elastic claw-shaped rear stopper must be precisely configured; poor machining of the parts or fatigue may cause the pen to work improperly.

Zaidman '084 (U.S. patent application publication no. 2011318084 ) discloses a retraction mechanism in which at a rearward position (as illustrated in fig. lb), a sliding weight 135 aligns an elongated instrument 120 with a rear canal 108 allowing the assembly to slide backward into the canal thereby retracting. When the weight 135 slides forward, it collides with a protrusion on the elongated instrument forcing the elongated instrument forward and pulling the rear end of the elongated instrument out of the rear canal into the extracted configuration as illustrated in fig. 1 a.

Zaidman '084, and the other citations above, depend on a sliding weight to activate the retraction mechanism. The use of a weight in itself is undesirable as it increases the overall weight of the instrument; the instrument is therefore less comfortable to use and to carry around, especially in a pocket of an elegant shirt. Moreover, the incorporation of the weight increases costs of production and shipping of the instrument. The use of a sliding weight as provided by Zaidman '084 and the other citations above, entails further drawbacks: it decreases longevity of the retraction mechanism due to fatigue, it compromises the reliability of the mechanism as the mechanism tends to jam over time due to slight deformation of the instrument which may be caused by temperature changes, or due to loss or aging of lubricants which are often applied to ensure smooth operation. Another disadvantage of the sliding weight is the knocking sounds which are produced each time the retraction mechanism is activated. These knocking sounds are annoying and, as a result, instruments incorporating such a retraction mechanism are considered less elegant in general and inappropriate to use at libraries, during tests or when undisrupted concentration is desired in particular.

Another common denominator of the retraction mechanism supported by Zaidman '084 and the other citations above is the use of inertia at a certain vector relatively to the instrument in which the retraction mechanism is installed in order to operate the retraction mechanism. For instance, the retraction mechanism of Zaidman '084 extends and retracts a tip of a pen by shaking or by inverting the pen. Each shake of the pen causes the tip of the pen to either extend out of the pen or to retract back into the body of the pen. Subsequent shaking reverses the effect of previous shaking. Shaking the pen by a sideways vector (i.e., laterally), will not activate the sliding weight and the retraction mechanism will not operate.

The art usually defines the direction of movement of objects through vectors; each vector can be represented by its corresponding vertical vector together with its horizontal vector. Horizontal shaking means when the horizontal vector is substantially larger than the vertical vector and vertical shaking means when the vertical vector is substantially larger than the horizontal vector, the terms horizontal and vertical are relative and depend on the axes in which the instrument is held, as further detailed in the descriptions. It would therefore be desirable to overcome some of the drawbacks of the prior art by a lightweight retraction mechanism which does not incorporate a designated sliding weigh which produces knocking sounds when the mechanism is activated. Providing a mechanism which operates by two different kinds of distinct movements would also be advantageous. SUMMARY OF THE INVENTION

The invention discloses a retraction mechanism for retracting a tip of an elongated instrument, the mechanism may comprise:

A) an internal shoulder located behind a bore of a barrel;

B) a rear canal located behind said internal shoulder;

C) an elongated instrument configured to slide along said bore, and

D) a forcing member;

wherein a brisk movement along the axis of the elongated instrument is used to extract a tip of the elongated instrument from the bore and a brisk movement across the axis of the elongated instrument is used to retract the tip of the elongated instrument inside the bore.

In a preferred embodiment, the sheer mass of the elongated instrument may be utilized to exert a force onto forcing member during brisk movements along the axis of the elongated instrument. In order to configure the mass of elongated instrument a weight attachment may be fixed to elongated instrument, the weigh attachment can be in the form of a sleeve and may be fixed nearby the shoulder to increase the moment which is applied on the elongated instrument during brisk movement across the axis of elongated instrument.

In a preferred embodiment, the brisk movement may be substantially longitudinal shaking along the axis of said elongated instrument and lateral shaking across the axis of said elongated instrument.

In a preferred embodiment, the elongated instrument and the forcing member may be the only parts of the retraction mechanism that are not fixed in relation to the barrel. The forcing member may be a simple compression spring which may be fixed at one end to the barrel or to the elongated instrument; the fixation can also be made via protrusions over the elongated instrument. In a preferred embodiment, the elongated instrument can be a standard pen refill. Alternatively a custom made refill may be designed in favor of the retraction mechanism.

In a preferred embodiment, the shoulder may be beveled to facilitate retraction of the elongated instrument from the shoulder into the rear canal during brisk movements across the axis of elongated instrument.

In a preferred embodiment, the retraction mechanism may further comprise a damping member such as elastic ring around the shoulder area or the rear canal in order to reduce knocking sounds during the activation of the retracting mechanism.

In a preferred embodiment the internal shoulder, the barrel and the canal may be formed by a single mold.

In a preferred embodiment the relations between the elongated instrument, the shoulder, the rear canal and the forcing member may be balanced to reduce a probability that said elongated instrument will spontaneously retract inadvertently.

In a preferred embodiment the tip may include at least one tool selected from the group containing a ball point pen, a fountain pen, a marker, a roll on applicator, a screw driver and a utility knife.

The invention discloses a method for retracting a tip of an elongated instrument out of a bore of a retraction mechanism by a single hand, the method may comprise the following steps;

a) holding the retraction mechanism in one hand as holding a pen;

b) shaking hand along axis of the elongated instrument thereby extracting the tip of elongated instrument out of the bore;

c) shaking hand across axis of the elongated instrument thereby retracting the tip of elongated instrument inside the bore. BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: Fig. la schematically shows a semi-cut-away view of a first embodiment of a retraction mechanism in a ball-point pen in an open configuration as provided by the prior art.

Fig. lb schematically shows a semi-cut-away view of a first embodiment of a retraction mechanism in a ball-point pen in a closed configuration as provided by the prior art.

Fig. 2a schematically shows a full cut-away view of a first embodiment of a retraction mechanism in a ball-point pen in the open configuration.

Fig. 2b schematically shows a full cut-away view of a first embodiment of a retraction mechanism in a ball-point pen in the closed configuration.

Fig. 3a schematically shows a full cut-away view of a second embodiment of a retraction mechanism in a ball-point pen in the open configuration.

Fig. 3b schematically shows a full cut-away view of a second embodiment of a retraction mechanism in a ball-point pen in the closed configuration. DETAILED DESCRIPTION OF THE INVENTION

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings. With specific reference to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of preferred embodiments of the present invention only, and are presented for the purpose of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. From the description taken together with the drawings it will be apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Moreover, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting the scope of the invention hereof. Figs, la schematically shows an embodiment 100 of a pen as disclosed in the US patent application of Zaidman '084 in an open configuration with writing tip 101 projected out of the front end of the pen, and fig. lb schematically shows embodiment 100 in a closed configuration with writing tip 101 retracted. The body of embodiment 100 is preferably approximately cylindrical and made up of two sections: the rear section includes a barrel 102 and the front section includes a pen nib 104. A sliding weight 135, preferentially in the form of a steel cylinder with a concentric cylindrical hollow, is provided for switching the pen of embodiment 100 between the closed configuration (Fig. lb) and the open configuration.(Fig. la). Sliding weight 135 slides freely along bore 106 and also slides freely over ink tube 120, which is confined within the hollow of sliding weight 135.

Figs. 2a and 2b schematically show a first embodiment 200 of a pen in an open configuration with writing tip 201 projected out of the front end of the pen, and fig. 2b schematically shows embodiment 200 in a closed configuration with writing tip 201 retracted. The body of embodiment 200 is preferably approximately cylindrical and made up of two sections: the rear section includes a barrel 202 and the front section includes a pen nib 204. Barrel 202 and pen nib 204 are preferentially detachably joined by a threaded connection to form the body of the pen. In Figs. 2a and 2b, the pen body is shown cut away to reveal the inside of barrel 202 which is hollowed to form a bore 206a and the inside of pen nib 204 which is hollowed to form a bore 206b. Bore 206a is in alignment with bore 206b when barrel 202 and pen nib 204 are joined.

At the rear end, opposite writing tip 201, bore 206a abruptly thins to a rear canal 208. In embodiment 200, barrel 202 is a single piece, but in an alternative embodiment, the rear portion of barrel 202 containing rear canal 208 could be a separate part, detachably joined to barrel 202 by a threaded connector. In such an alternative embodiment (where the rear end of the pen is removable), the pen nib and barrel may be permanently joined (for example they may constitute a single molded part) and the pen refill may be inserted from the rear of the pen.

Where the rear canal 208 meets the wider bore 206a there is formed an internal shoulder 210. In embodiment 200, rear canal 208 and wider bore 206a both have a cylindrical form and circular cross-section and are aligned concentrically so that internal shoulder 210 has a ring form.

In embodiment 200, writing tip 201 is part of an elongated instrument which is a standard pen refill consisting of an ink tube 220, a protrusion 230 and writing tip 201. In embodiment 200, protrusion 230 is an integral part of the ink tube 220. Protrusion 230 may be a separate piece that is permanently or detachably attached to ink tube 220. Alternatively, protrusions which are common at some standard pen refills may be utilized. As is well known in the art, in standard pen refills, protrusion 230 may be a pinched portion of ink tube 220 that is configured to engage and hold back a forcing member. In embodiment 200 the forcing member is a compression spring 225. The front end of compression spring 225 is fixed to the front of pen nib 204. When compression spring 225 is engaged to protrusion 230, compression spring 225 forces the refill (writing tip 201, ink tube 220 and protrusion 230) towards the rear end of the pen body.

Alternatively a forcing member may be a deformable elastic plastic leaf or stretchable band or a magnet or other suitable material. The force may be a compression or stretching force of a deformable member or an electromagnetic force. For a softer resistance of the forcing member, ink tube 220 may be configured to be lighter, and as a result, the overall weight of the retracting mechanism may be reduced. Moreover, the decrease in weight and size can be utilized to design finer instruments.

In the open configuration of Fig. 2a, the rear end of ink tube 220 is in contact with internal shoulder 210 which prevents ink tube 220 from moving rearward into rear canal 208. The length of the pen refill (the combined length of ink tube 220 and writing tip 201) is greater than the combined lengths of bores 206a and 206b. Therefore when the rear of ink tube 220 is in contact with internal shoulder 210, writing tip 201 extends out of the front of pen nib 204 as illustrated in Fig. 2a. In the open configuration of fig. 2a, compression spring 225 holds ink tube 220 firmly against internal shoulder 210 thus writing tip 201 is held firmly in the protruding position without play, making the pen of embodiment 200 a comfortable writing instrument.

In the closed configuration of Fig. 2b, the rear end of ink tube 220 is pushed by compression spring 225 into rear canal 208. The combined length of rear canal 208, bore 206a and bore 206b is slightly longer than the length of the elongated member (the pen refill including ink tube 220 and writing tip 201). Therefore, when the rear portion of ink tube 220 is pushed into rear canal 208, writing tip 201 is retracted into bore 206b as illustrated in fig. 2b.

When pen 200 is in the open configuration of fig. 2a, shaking pen 200 sideways (in a direction perpendicular to the long axis of pen 200) exerts a moment on ink tube 220 which causes ink tube 220 to slide off of internal shoulder 210 back into alignment in rear canal 208 to the closed configuration. Ink tube 220 may be forced forward or rearward by shaking pen 200 longitudinally (in a direction parallel to the long axes of pen 200). The method and force necessary to force ink tube 220 forward (by longitudinal shaking) or rearward (by sideways shaking) may depend on the application, the geometry of internal shoulder 210, the materials used, the size of ink tube 220 and the stiffness of compression spring 225. Once ink tube 220 is aligned with rear canal 208, compression spring 225 forces the rear portion of ink tube 220 into the closed configuration inside rear canal 208 retracting writing tip 201 into pen nib 204 as illustrated in fig. 2b.

When the pen is in the closed configuration of fig. 2b, shaking pen 200 forward causes ink tube 220 to compress protrusion 230 and push protrusion 230 and hence all of the elongated member (writing tip 201, protrusion 230 and ink tube 220) forward. This compresses compression spring 225 and causes ink tube 220 to slide out of rear canal 208. Once ink tube 220 leaves canal 208, compression spring 225 pushes ink tube 220 back against internal shoulder 210 thus the tip extend firmly out of pen nib 204 for comfortable use.

The entrance to rear canal 208 is configured so that ink tube 220 is unlikely to spontaneously align with rear canal 208. This is accomplished in embodiment 200 by making the diameter of the entrance to rear canal 220 small so that ink tube 220 will only enter rear canal 208 when ink tube 220 and rear canal 208 are practically aligned. A small misalignment prevents ink tube 220 from entering rear canal 208 and causes ink tube 220 to lock against internal shoulder 210 locking the pen in the open configuration. Preferably, the probability of ink tube 220 to spontaneously being precisely aligned with rear canal 208 is as small as possible while allowing easy closing of the pen when ink tube 220 is forced sideways aligning ink tube 220 and rear canal 208. Preferably rear canal 208 is larger than the rear of the elongated instrument (in embodiment 200 this means that the diameter of rear canal 208 is greater than the diameter of ink tube 220). Furthermore, due to machining imprecision, ink tube 220 may not be perfectly straight, further decreasing the probability of spontaneous alignment between ink tube 220 and rear canal 208. Therefore, once pulled out of rear canal 208, ink tube 220 will probably be pushed onto internal shoulder 210 and held in the open configuration of fig. 2a until ink tube 220 is again forced sideways back into precise alignment with rear canal 208. By the above mechanism, based only on probability of alignment, forcing ink tube 220 forward (by vertical shaking) will usually open the pen regardless of the attitude of the pen (whether it is held tip down, tip up or on a slant). In a similar manner, a brisk shake of pen 200 sideways will probably cause ink tube 220 to slide off of internal shoulder 210 back into rear canal 208, thus closing pen 200. In other words, longitudinal shaking is used to open pen 200 and lateral (sideways, side to side) shaking is used to close pen 200. The terms longitudinal and lateral are relative to pen 200. The direction of movement in order to open pen 200 will always be alongside pen and the directional of movement to close pen 200 will always be across pen 200. The art usually defines the direction of movement of objects through vectors; each vector can be represented by its corresponding vertical vector together with its horizontal vector. Horizontal shaking means when the horizontal vector is substantially larger than the vertical vector and vertical shaking means when the vertical vector is substantially larger than the horizontal vector.

According to embodiment 200, the sheer mass of ink tube 220 is utilized to leverage the momentum applied by the user in order to activate the retraction mechanism whether by longitudinal shaking by the user which is utilized in order to extract pen tip 201 and whether by lateral shaking by the user which is utilized to retract pen tip 201, this is possible due to the interaction between the mass of ink tube 220 to the winding of compression spring225. In various alternative embodiments, the rear canal is larger than the rear of the elongated instrument (the rear canal should be as small as possible but large enough for elongated instrument to easily enter the rear canal when the rear canal and the elongated instrument are aligned by horizontal shaking of the pen 200). This would correspond to a low probability of spontaneous closure of the pen from fully extruded configuration (when the elongated instrument is extruded beyond the open writing configuration, beyond the point of locking against inner shoulder 210). In the preferred embodiment the probability of spontaneous closure from the fully extruded configuration is small. It should be noted that this low probability of spontaneous closure is not dependent on the attitude at which the pen is held.

The method by which a user will open and close the pen depends on the ratio of the mass of ink tube 220 and the retaining force of compression spring 225. Particularly, if compression spring 225 is soft and ink tube 220 is heavy, then when the pen is tipped with writing tip 201 downward, the weight of ink tube 220 will pull ink tube 220 out of rear canal 208 opening the pen. This situation may be undesirable because the pen may open unexpectedly (staining clothes etc.). Furthermore, when held with writing tip 201 downward, ink tube 220 will not be pushed up against internal shoulder 210 and the writing tip 201 will move slightly inward before commencing to write. Preferably, for a stiffer compression spring 225 and a lighter ink tube 220 opening the pen will require a brisk vertical shake of the pen to cause ink tube 220 to travel forward with momentum out of rear canal 208. Similarly, a brisk horizontal shake of the pen will push ink tube 220 with high momentum sideways, dislodging ink tube 220 from interior shoulder 210 and aligning ink tube 220 with rear canal 208 such that compression spring 225 pushes ink tube 220 into rear canal 208, closing the pen. For smaller, thinner pens it is possible to use a softer spring as the forcing member and a lighter ink tube 220. Alternatively, compression spring 225 could be replaced by another mechanism, for example a deformable piece of elastic plastic.

In order to smooth the sliding off internal shoulder 210 of ink tube 220, lubrication is applied on internal shoulder 210 and upper tip of ink tube 220 which comes in contact with internal shoulder 210. Thus, friction between internal shoulder 210 and ink tube 220 is reduced during the lateral shaking to retract ink tube 220 off internal shoulder 210 of the mechanism. As a result, slighter force can be exerted to retract ink tube 220 and abrasion is reduced.

The retraction mechanism is designed not to be activated below the exertion of a certain degree of force in order to prevent inadvertent extension or retraction of tip 201 (e.g., when a person carrying such a pen descends stairs) and in order to maintain extraction of front tip 201 during non vertical use (e.g., during writing on a wall). In other words, delicate shaking of the pen (both vertically and horizontally) will probably not trigger the activation of mechanism 200.

A rubber ring is glued on the surface of internal shoulder 210 and at the tip of rear canal 208 as a damping member in order to attenuate knocking sounds during shaking. Alternatively, small pieces of sponge-like material can be attached to either side of ink tube 220. Naturally, various kinds of lubrication and shock absorbents can be applied to smoothen the operation of the mechanism and to avoid abrasion. Figs 3a and 3b illustrate a second embodiment 300 of a retraction mechanism for a pen in an open and closed configuration, respectively. Embodiment 300 functions in a similar manner to embodiment 200 and includes similar parts. Particularly, embodiment 300 includes a pen body made up of two sections, a barrel 302 forms the rear section and a pen nib 304 forms the front section. Each section is hollowed out to form a bore 306a inside of barrel 302 and a bore 306b inside of pen nib 304. Bore 306a is in alignment with bore 306b when barrel 302 and pen nib 304 are joined. At the rear end, opposite to writing tip 301, bore 306a abruptly thins to a rear canal 308. Where rear canal 308 meets bore 306a there is formed an internal shoulder 310. Embodiment 300 also includes a forcing member which is a compression spring 325 similar to embodiment 200.

The elongated instrument of embodiment 300 includes a writing tip 301 and ink tube 320 similar to embodiment 200 but in contrast to embodiment 200, the elongated instrument of embodiment 300 includes a sleeve 340 which surrounds ink tube 320. In this embodiment 300, sleeve 340 is attached to ink tube; sleeve 340 may also be designed as an integral part of ink tube 320. In such embodiments, sleeve 340 serves as an additional weight and its protrusion 330 is utilized to increase the reliability of the mechanism. The additional weight of sleeve 340 compensates for weigh variations which may occur due to the dispensing of the ink from ink tube 320; such variations could otherwise effect the operation of the mechanism which is dependent on the delicate ratio between the weight of ink tube 320 to compression spring 325. It is understood that sleeve 340 can be manufactured in various shapes, sizes and materials in accordance with the tuning of the calculations of the operation of the retraction mechanism, the sleeve may be attached to ink tube by friction or by adhesions such that sleeve and ink tube are coupled and therefore retracted together as a single unit. Sleeve 340 can therefore be based on a simple attachment to ink tube 320 to add some mass to ink tube 320 in order to reach the required ratio between ink tube 320, to the specific winding of compression spring 325. For instance, in an alternative embodiment, the upper end of ink tube (the end which is close to the rear canal 308) 320 may be designed to be heavier in order to increase the moment applied on the far end of ink tube 320 (the end which is close to shoulder 310) during horizontal shaking to ease the closing of pen 300.

Sleeve 340 includes a protrusion 330 (in fig. 3b the sleeve is shown cut away for illustration purposes). When pen 300 is in the configuration of fig. 3b (i.e., closed such that writing tip 301 is shielded inside pen nib 304), forcing ink tube 320 downwards (for example by moving pen 300 towards the ground or by shaking pen 300 up and down) causes sleeve 340, which is attached to ink tube 320, to apply pressure onto compression spring 325. The pressure compresses compression spring 325. Thereby, ink tube 320 exists rear canal 308 and comes to rest on shoulder 310 as can be seen in fig. 3a, which show pen 300 in an open configuration (i.e., writing tip 302 extends pen nib 304). In the configuration of fig. 3a, applying force downwards once again (whether by a single movement or by shaking) will not activate retraction mechanism because ink tube 320 is forced against shoulder 310 by the compressed compression spring 325. In order to revert pen 300 back to the closed configuration of fig. 3b, force is to be exerted lateral (i.e., pen 300 is moved or shaken sideways such that movement is substantially across the axis of ink tube 320), thus moment is applied over the rear tip of ink tube causing ink tube 320 to slide off of shoulder 310 back into rear canal 308. In the configuration of fig. 3b, applying force sideways once again (whether by a single movement or by shaking) will not cause pen 300 to open because ink tube 320 is compressed inside of rear canal 308 by the compression spring. In order to revert pen 300 back to the opened configuration of fig. 3a, force is to be exerted downwards (longitudinally along the long axis of pen 300). In embodiments 200 and 300 the retraction mechanism is activated by forces which are applied substantially either along or across ink tube 320. Although the retraction mechanism may be activated by a single movement in the required direction, the user may choose to shake or to jerk the instrument back and forth along the required axis. In embodiment 300, protrusion 330 also serves for engaging compression spring 325.

Alternatively, ink tube 320 may have a separate protrusion to engage compression spring 325. In such an alternative embodiment compression spring 325 would press against the protrusion on ink tube 320 forcing ink tube 320 into sleeve 340.1n such an alternative embodiment the force of ink tube 320 against sleeve 340 would lock sleeve 340 against shoulder 310 when the pen is in the open configuration and hold sleeve 340 inside rear canal 308 when the pen is in the closed configuration.

The opening and closing action of embodiment 300 is exactly analogous to embodiment 200, except that to close embodiment 300, sleeve 340 is aligned with rear canal 308, as opposed to the alignment of ink tube 220 with rear canal 208. An advantage of embodiment 300 over embodiment 200 is that the only part that directly interacts with the pen refill (ink tube 320 and writing tip 301) is sleeve 340. This makes it possible to adjust the geometry of bore 306a and 306b and rear canal 308and still use a standard pen refill (inserted into sleeve 340), another advantage would be the dismissal of the spring / refill delicate mass ratio.

Other approaches can be applied into practice in order to smooth the operation of the retraction mechanism. Bores 306a, 306b, rear canal 308, elongated instrument 320 and shoulder 310 can be beveled in various shapes and configurations in order to smoothen the operation of the retraction mechanism. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

Claims

WHAT IS CLAIMED IS:

1. A retraction mechanism for retracting a tip of an elongated instrument comprising:

A) an internal shoulder located behind a bore of a barrel;

B) a rear canal located behind said internal shoulder;

C) an elongated instrument configured to slide along said bore, and

D) a forcing member;

2. The retraction mechanism of claim 1, wherein the sheer mass of the elongated instrument is utilized to exert a force onto forcing member during brisk movements along the axis of the elongated instrument.

3. The retraction mechanism of claim 1, wherein the brisk movement is substantially longitudinal shaking along the axis of said elongated instrument.

4. The retraction mechanism of claim 1, wherein the brisk movement is substantially lateral shaking across the axis of said elongated instrument.

5. The retraction mechanism of claim 2, wherein the sheer mass of said elongated instrument is reconfigured by an attachment fixed to the elongated instrument.

6. The retraction mechanism of claim 5, wherein the attachment to the upper end of elongated instrument increases the moment applied over elongated instrument during brisk movement across the axis of elongated instrument.

7. The retraction mechanism of claim 1, wherein the elongated instrument and the forcing member are the only parts of the retraction mechanism that are not fixed in relation to the barrel.

8. The retraction mechanism of claim 1, wherein at least one end of the forcing member is fixed with respect to the barrel.

9. The retraction mechanism of claim 1, wherein said elongated instrument includes a standard pen refill.

10. The retraction mechanism of claim 1 , wherein a protrusion over elongated instrument is used to fix at least one end of the forcing member to the elongated instrument.

11. The retraction mechanism of claim 10, wherein the protrusion includes at least one element selected from the group containing a pinched protrusion of a standard pen refill, a protrusion added to a pen refill, a cylinder encasing at least part of the elongated instrument other than its tip and a nut.

12. The retraction mechanism of claim 1, wherein the shoulder is beveled.

13. The retraction mechanism of claim 1, further comprising a damping member.

14. The retraction mechanism of claim 1, wherein the internal shoulder, the barrel and the canal are formed by a single mold.

15. The retraction mechanism of claim 1, wherein the relations between the elongated instrument, the shoulder, the rear canal and the forcing member are configured to reduce a probability that said elongated instrument will spontaneously retract.

16. The retraction mechanism of claim 1, wherein the tip includes at least one tool selected from the group containing a ball point pen, a fountain pen, a marker, a roll on applicator, a screw driver and a utility knife.

17. The retraction mechanism of claim 1, wherein said retraction mechanism is not activated under a certain degree of force.

18. A method for retracting a tip of an elongated instrument out of a bore of a retraction mechanism by a single hand comprising the following steps;

a) holding the retraction mechanism in one hand as holding a pen;

c) shaking hand across axis of the elongated instrument thereby retracting the tip of elongated instrument inside the bore.